ri_triggers.c

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/* ----------
 * ri_triggers.c
 *
 *  Generic trigger procedures for referential integrity constraint
 *  checks.
 *
 *  Note about memory management: the private hashtables kept here live
 *  across query and transaction boundaries, in fact they live as long as
 *  the backend does.  This works because the hashtable structures
 *  themselves are allocated by dynahash.c in its permanent DynaHashCxt,
 *  and the SPI plans they point to are saved using SPI_keepplan().
 *  There is not currently any provision for throwing away a no-longer-needed
 *  plan --- consider improving this someday.
 *
 *
 * Portions Copyright (c) 1996-2013, PostgreSQL Global Development Group
 *
 * src/backend/utils/adt/ri_triggers.c
 *
 * ----------
 */


/* ----------
 * Internal TODO:
 *
 *      Add MATCH PARTIAL logic.
 * ----------
 */

#include "postgres.h"

#include "access/htup_details.h"
#include "access/sysattr.h"
#include "access/xact.h"
#include "catalog/pg_collation.h"
#include "catalog/pg_constraint.h"
#include "catalog/pg_operator.h"
#include "catalog/pg_type.h"
#include "commands/trigger.h"
#include "executor/executor.h"
#include "executor/spi.h"
#include "parser/parse_coerce.h"
#include "parser/parse_relation.h"
#include "miscadmin.h"
#include "utils/builtins.h"
#include "utils/fmgroids.h"
#include "utils/guc.h"
#include "utils/inval.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
#include "utils/rel.h"
#include "utils/snapmgr.h"
#include "utils/syscache.h"
#include "utils/tqual.h"


/* ----------
 * Local definitions
 * ----------
 */

#define RI_MAX_NUMKEYS                  INDEX_MAX_KEYS

#define RI_INIT_CONSTRAINTHASHSIZE      64
#define RI_INIT_QUERYHASHSIZE           (RI_INIT_CONSTRAINTHASHSIZE * 4)

#define RI_KEYS_ALL_NULL                0
#define RI_KEYS_SOME_NULL               1
#define RI_KEYS_NONE_NULL               2

/* RI query type codes */
/* these queries are executed against the PK (referenced) table: */
#define RI_PLAN_CHECK_LOOKUPPK          1
#define RI_PLAN_CHECK_LOOKUPPK_FROM_PK  2
#define RI_PLAN_LAST_ON_PK              RI_PLAN_CHECK_LOOKUPPK_FROM_PK
/* these queries are executed against the FK (referencing) table: */
#define RI_PLAN_CASCADE_DEL_DODELETE    3
#define RI_PLAN_CASCADE_UPD_DOUPDATE    4
#define RI_PLAN_RESTRICT_DEL_CHECKREF   5
#define RI_PLAN_RESTRICT_UPD_CHECKREF   6
#define RI_PLAN_SETNULL_DEL_DOUPDATE    7
#define RI_PLAN_SETNULL_UPD_DOUPDATE    8
#define RI_PLAN_SETDEFAULT_DEL_DOUPDATE 9
#define RI_PLAN_SETDEFAULT_UPD_DOUPDATE 10

#define MAX_QUOTED_NAME_LEN  (NAMEDATALEN*2+3)
#define MAX_QUOTED_REL_NAME_LEN  (MAX_QUOTED_NAME_LEN*2)

#define RIAttName(rel, attnum)  NameStr(*attnumAttName(rel, attnum))
#define RIAttType(rel, attnum)  attnumTypeId(rel, attnum)
#define RIAttCollation(rel, attnum) attnumCollationId(rel, attnum)

#define RI_TRIGTYPE_INSERT 1
#define RI_TRIGTYPE_UPDATE 2
#define RI_TRIGTYPE_DELETE 3


/* ----------
 * RI_ConstraintInfo
 *
 *  Information extracted from an FK pg_constraint entry.  This is cached in
 *  ri_constraint_cache.
 * ----------
 */
typedef struct RI_ConstraintInfo
{
    Oid         constraint_id;  /* OID of pg_constraint entry (hash key) */
    bool        valid;          /* successfully initialized? */
    uint32      oidHashValue;   /* hash value of pg_constraint OID */
    NameData    conname;        /* name of the FK constraint */
    Oid         pk_relid;       /* referenced relation */
    Oid         fk_relid;       /* referencing relation */
    char        confupdtype;    /* foreign key's ON UPDATE action */
    char        confdeltype;    /* foreign key's ON DELETE action */
    char        confmatchtype;  /* foreign key's match type */
    int         nkeys;          /* number of key columns */
    int16       pk_attnums[RI_MAX_NUMKEYS];     /* attnums of referenced cols */
    int16       fk_attnums[RI_MAX_NUMKEYS];     /* attnums of referencing cols */
    Oid         pf_eq_oprs[RI_MAX_NUMKEYS];     /* equality operators (PK =
                                                 * FK) */
    Oid         pp_eq_oprs[RI_MAX_NUMKEYS];     /* equality operators (PK =
                                                 * PK) */
    Oid         ff_eq_oprs[RI_MAX_NUMKEYS];     /* equality operators (FK =
                                                 * FK) */
} RI_ConstraintInfo;


/* ----------
 * RI_QueryKey
 *
 *  The key identifying a prepared SPI plan in our query hashtable
 * ----------
 */
typedef struct RI_QueryKey
{
    Oid         constr_id;      /* OID of pg_constraint entry */
    int32       constr_queryno; /* query type ID, see RI_PLAN_XXX above */
} RI_QueryKey;


/* ----------
 * RI_QueryHashEntry
 * ----------
 */
typedef struct RI_QueryHashEntry
{
    RI_QueryKey key;
    SPIPlanPtr  plan;
} RI_QueryHashEntry;


/* ----------
 * RI_CompareKey
 *
 *  The key identifying an entry showing how to compare two values
 * ----------
 */
typedef struct RI_CompareKey
{
    Oid         eq_opr;         /* the equality operator to apply */
    Oid         typeid;         /* the data type to apply it to */
} RI_CompareKey;


/* ----------
 * RI_CompareHashEntry
 * ----------
 */
typedef struct RI_CompareHashEntry
{
    RI_CompareKey key;
    bool        valid;          /* successfully initialized? */
    FmgrInfo    eq_opr_finfo;   /* call info for equality fn */
    FmgrInfo    cast_func_finfo;    /* in case we must coerce input */
} RI_CompareHashEntry;


/* ----------
 * Local data
 * ----------
 */
static HTAB *ri_constraint_cache = NULL;
static HTAB *ri_query_cache = NULL;
static HTAB *ri_compare_cache = NULL;


/* ----------
 * Local function prototypes
 * ----------
 */
static bool ri_Check_Pk_Match(Relation pk_rel, Relation fk_rel,
                  HeapTuple old_row,
                  const RI_ConstraintInfo *riinfo);
static Datum ri_restrict_del(TriggerData *trigdata, bool is_no_action);
static Datum ri_restrict_upd(TriggerData *trigdata, bool is_no_action);
static void quoteOneName(char *buffer, const char *name);
static void quoteRelationName(char *buffer, Relation rel);
static void ri_GenerateQual(StringInfo buf,
                const char *sep,
                const char *leftop, Oid leftoptype,
                Oid opoid,
                const char *rightop, Oid rightoptype);
static void ri_add_cast_to(StringInfo buf, Oid typid);
static void ri_GenerateQualCollation(StringInfo buf, Oid collation);
static int ri_NullCheck(HeapTuple tup,
             const RI_ConstraintInfo *riinfo, bool rel_is_pk);
static void ri_BuildQueryKey(RI_QueryKey *key,
                 const RI_ConstraintInfo *riinfo,
                 int32 constr_queryno);
static bool ri_KeysEqual(Relation rel, HeapTuple oldtup, HeapTuple newtup,
             const RI_ConstraintInfo *riinfo, bool rel_is_pk);
static bool ri_AttributesEqual(Oid eq_opr, Oid typeid,
                   Datum oldvalue, Datum newvalue);

static void ri_InitHashTables(void);
static void InvalidateConstraintCacheCallBack(Datum arg, int cacheid, uint32 hashvalue);
static SPIPlanPtr ri_FetchPreparedPlan(RI_QueryKey *key);
static void ri_HashPreparedPlan(RI_QueryKey *key, SPIPlanPtr plan);
static RI_CompareHashEntry *ri_HashCompareOp(Oid eq_opr, Oid typeid);

static void ri_CheckTrigger(FunctionCallInfo fcinfo, const char *funcname,
                int tgkind);
static const RI_ConstraintInfo *ri_FetchConstraintInfo(Trigger *trigger,
                       Relation trig_rel, bool rel_is_pk);
static const RI_ConstraintInfo *ri_LoadConstraintInfo(Oid constraintOid);
static SPIPlanPtr ri_PlanCheck(const char *querystr, int nargs, Oid *argtypes,
             RI_QueryKey *qkey, Relation fk_rel, Relation pk_rel,
             bool cache_plan);
static bool ri_PerformCheck(const RI_ConstraintInfo *riinfo,
                RI_QueryKey *qkey, SPIPlanPtr qplan,
                Relation fk_rel, Relation pk_rel,
                HeapTuple old_tuple, HeapTuple new_tuple,
                bool detectNewRows, int expect_OK);
static void ri_ExtractValues(Relation rel, HeapTuple tup,
                 const RI_ConstraintInfo *riinfo, bool rel_is_pk,
                 Datum *vals, char *nulls);
static void ri_ReportViolation(const RI_ConstraintInfo *riinfo,
                   Relation pk_rel, Relation fk_rel,
                   HeapTuple violator, TupleDesc tupdesc,
                   int queryno, bool spi_err);


/* ----------
 * RI_FKey_check -
 *
 *  Check foreign key existence (combined for INSERT and UPDATE).
 * ----------
 */
static Datum
RI_FKey_check(TriggerData *trigdata)
{
    const RI_ConstraintInfo *riinfo;
    Relation    fk_rel;
    Relation    pk_rel;
    HeapTuple   new_row;
    Buffer      new_row_buf;
    RI_QueryKey qkey;
    SPIPlanPtr  qplan;
    int         i;

    /*
     * Get arguments.
     */
    riinfo = ri_FetchConstraintInfo(trigdata->tg_trigger,
                                    trigdata->tg_relation, false);

    if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
    {
        new_row = trigdata->tg_newtuple;
        new_row_buf = trigdata->tg_newtuplebuf;
    }
    else
    {
        new_row = trigdata->tg_trigtuple;
        new_row_buf = trigdata->tg_trigtuplebuf;
    }

    /*
     * We should not even consider checking the row if it is no longer valid,
     * since it was either deleted (so the deferred check should be skipped)
     * or updated (in which case only the latest version of the row should be
     * checked).  Test its liveness according to SnapshotSelf.
     *
     * NOTE: The normal coding rule is that one must acquire the buffer
     * content lock to call HeapTupleSatisfiesVisibility.  We can skip that
     * here because we know that AfterTriggerExecute just fetched the tuple
     * successfully, so there cannot be a VACUUM compaction in progress on the
     * page (either heap_fetch would have waited for the VACUUM, or the
     * VACUUM's LockBufferForCleanup would be waiting for us to drop pin). And
     * since this is a row inserted by our open transaction, no one else can
     * be entitled to change its xmin/xmax.
     */
    Assert(new_row_buf != InvalidBuffer);
    if (!HeapTupleSatisfiesVisibility(new_row, SnapshotSelf, new_row_buf))
        return PointerGetDatum(NULL);

    /*
     * Get the relation descriptors of the FK and PK tables.
     *
     * pk_rel is opened in RowShareLock mode since that's what our eventual
     * SELECT FOR KEY SHARE will get on it.
     */
    fk_rel = trigdata->tg_relation;
    pk_rel = heap_open(riinfo->pk_relid, RowShareLock);

    if (riinfo->confmatchtype == FKCONSTR_MATCH_PARTIAL)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("MATCH PARTIAL not yet implemented")));

    switch (ri_NullCheck(new_row, riinfo, false))
    {
        case RI_KEYS_ALL_NULL:

            /*
             * No further check needed - an all-NULL key passes every type of
             * foreign key constraint.
             */
            heap_close(pk_rel, RowShareLock);
            return PointerGetDatum(NULL);

        case RI_KEYS_SOME_NULL:

            /*
             * This is the only case that differs between the three kinds of
             * MATCH.
             */
            switch (riinfo->confmatchtype)
            {
                case FKCONSTR_MATCH_FULL:

                    /*
                     * Not allowed - MATCH FULL says either all or none of the
                     * attributes can be NULLs
                     */
                    ereport(ERROR,
                            (errcode(ERRCODE_FOREIGN_KEY_VIOLATION),
                             errmsg("insert or update on table \"%s\" violates foreign key constraint \"%s\"",
                                    RelationGetRelationName(fk_rel),
                                    NameStr(riinfo->conname)),
                             errdetail("MATCH FULL does not allow mixing of null and nonnull key values."),
                             errtableconstraint(fk_rel,
                                                NameStr(riinfo->conname))));
                    heap_close(pk_rel, RowShareLock);
                    return PointerGetDatum(NULL);

                case FKCONSTR_MATCH_SIMPLE:

                    /*
                     * MATCH SIMPLE - if ANY column is null, the key passes
                     * the constraint.
                     */
                    heap_close(pk_rel, RowShareLock);
                    return PointerGetDatum(NULL);

                case FKCONSTR_MATCH_PARTIAL:

                    /*
                     * MATCH PARTIAL - all non-null columns must match. (not
                     * implemented, can be done by modifying the query below
                     * to only include non-null columns, or by writing a
                     * special version here)
                     */
                    ereport(ERROR,
                            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                             errmsg("MATCH PARTIAL not yet implemented")));
                    heap_close(pk_rel, RowShareLock);
                    return PointerGetDatum(NULL);

                default:
                    elog(ERROR, "unrecognized confmatchtype: %d",
                         riinfo->confmatchtype);
                    break;
            }

        case RI_KEYS_NONE_NULL:

            /*
             * Have a full qualified key - continue below for all three kinds
             * of MATCH.
             */
            break;
    }

    if (SPI_connect() != SPI_OK_CONNECT)
        elog(ERROR, "SPI_connect failed");

    /*
     * Fetch or prepare a saved plan for the real check
     */
    ri_BuildQueryKey(&qkey, riinfo, RI_PLAN_CHECK_LOOKUPPK);

    if ((qplan = ri_FetchPreparedPlan(&qkey)) == NULL)
    {
        StringInfoData querybuf;
        char        pkrelname[MAX_QUOTED_REL_NAME_LEN];
        char        attname[MAX_QUOTED_NAME_LEN];
        char        paramname[16];
        const char *querysep;
        Oid         queryoids[RI_MAX_NUMKEYS];

        /* ----------
         * The query string built is
         *  SELECT 1 FROM ONLY <pktable> x WHERE pkatt1 = $1 [AND ...]
         *         FOR KEY SHARE OF x
         * The type id's for the $ parameters are those of the
         * corresponding FK attributes.
         * ----------
         */
        initStringInfo(&querybuf);
        quoteRelationName(pkrelname, pk_rel);
        appendStringInfo(&querybuf, "SELECT 1 FROM ONLY %s x", pkrelname);
        querysep = "WHERE";
        for (i = 0; i < riinfo->nkeys; i++)
        {
            Oid         pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
            Oid         fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);

            quoteOneName(attname,
                         RIAttName(pk_rel, riinfo->pk_attnums[i]));
            sprintf(paramname, "$%d", i + 1);
            ri_GenerateQual(&querybuf, querysep,
                            attname, pk_type,
                            riinfo->pf_eq_oprs[i],
                            paramname, fk_type);
            querysep = "AND";
            queryoids[i] = fk_type;
        }
        appendStringInfo(&querybuf, " FOR KEY SHARE OF x");

        /* Prepare and save the plan */
        qplan = ri_PlanCheck(querybuf.data, riinfo->nkeys, queryoids,
                             &qkey, fk_rel, pk_rel, true);
    }

    /*
     * Now check that foreign key exists in PK table
     */
    ri_PerformCheck(riinfo, &qkey, qplan,
                    fk_rel, pk_rel,
                    NULL, new_row,
                    false,
                    SPI_OK_SELECT);

    if (SPI_finish() != SPI_OK_FINISH)
        elog(ERROR, "SPI_finish failed");

    heap_close(pk_rel, RowShareLock);

    return PointerGetDatum(NULL);
}


/* ----------
 * RI_FKey_check_ins -
 *
 *  Check foreign key existence at insert event on FK table.
 * ----------
 */
Datum
RI_FKey_check_ins(PG_FUNCTION_ARGS)
{
    /*
     * Check that this is a valid trigger call on the right time and event.
     */
    ri_CheckTrigger(fcinfo, "RI_FKey_check_ins", RI_TRIGTYPE_INSERT);

    /*
     * Share code with UPDATE case.
     */
    return RI_FKey_check((TriggerData *) fcinfo->context);
}


/* ----------
 * RI_FKey_check_upd -
 *
 *  Check foreign key existence at update event on FK table.
 * ----------
 */
Datum
RI_FKey_check_upd(PG_FUNCTION_ARGS)
{
    /*
     * Check that this is a valid trigger call on the right time and event.
     */
    ri_CheckTrigger(fcinfo, "RI_FKey_check_upd", RI_TRIGTYPE_UPDATE);

    /*
     * Share code with INSERT case.
     */
    return RI_FKey_check((TriggerData *) fcinfo->context);
}


/* ----------
 * ri_Check_Pk_Match
 *
 * Check to see if another PK row has been created that provides the same
 * key values as the "old_row" that's been modified or deleted in our trigger
 * event.  Returns true if a match is found in the PK table.
 *
 * We assume the caller checked that the old_row contains no NULL key values,
 * since otherwise a match is impossible.
 * ----------
 */
static bool
ri_Check_Pk_Match(Relation pk_rel, Relation fk_rel,
                  HeapTuple old_row,
                  const RI_ConstraintInfo *riinfo)
{
    SPIPlanPtr  qplan;
    RI_QueryKey qkey;
    int         i;
    bool        result;

    /* Only called for non-null rows */
    Assert(ri_NullCheck(old_row, riinfo, true) == RI_KEYS_NONE_NULL);

    if (SPI_connect() != SPI_OK_CONNECT)
        elog(ERROR, "SPI_connect failed");

    /*
     * Fetch or prepare a saved plan for checking PK table with values coming
     * from a PK row
     */
    ri_BuildQueryKey(&qkey, riinfo, RI_PLAN_CHECK_LOOKUPPK_FROM_PK);

    if ((qplan = ri_FetchPreparedPlan(&qkey)) == NULL)
    {
        StringInfoData querybuf;
        char        pkrelname[MAX_QUOTED_REL_NAME_LEN];
        char        attname[MAX_QUOTED_NAME_LEN];
        char        paramname[16];
        const char *querysep;
        Oid         queryoids[RI_MAX_NUMKEYS];

        /* ----------
         * The query string built is
         *  SELECT 1 FROM ONLY <pktable> x WHERE pkatt1 = $1 [AND ...]
         *         FOR KEY SHARE OF x
         * The type id's for the $ parameters are those of the
         * PK attributes themselves.
         * ----------
         */
        initStringInfo(&querybuf);
        quoteRelationName(pkrelname, pk_rel);
        appendStringInfo(&querybuf, "SELECT 1 FROM ONLY %s x", pkrelname);
        querysep = "WHERE";
        for (i = 0; i < riinfo->nkeys; i++)
        {
            Oid         pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);

            quoteOneName(attname,
                         RIAttName(pk_rel, riinfo->pk_attnums[i]));
            sprintf(paramname, "$%d", i + 1);
            ri_GenerateQual(&querybuf, querysep,
                            attname, pk_type,
                            riinfo->pp_eq_oprs[i],
                            paramname, pk_type);
            querysep = "AND";
            queryoids[i] = pk_type;
        }
        appendStringInfo(&querybuf, " FOR KEY SHARE OF x");

        /* Prepare and save the plan */
        qplan = ri_PlanCheck(querybuf.data, riinfo->nkeys, queryoids,
                             &qkey, fk_rel, pk_rel, true);
    }

    /*
     * We have a plan now. Run it.
     */
    result = ri_PerformCheck(riinfo, &qkey, qplan,
                             fk_rel, pk_rel,
                             old_row, NULL,
                             true,      /* treat like update */
                             SPI_OK_SELECT);

    if (SPI_finish() != SPI_OK_FINISH)
        elog(ERROR, "SPI_finish failed");

    return result;
}


/* ----------
 * RI_FKey_noaction_del -
 *
 *  Give an error and roll back the current transaction if the
 *  delete has resulted in a violation of the given referential
 *  integrity constraint.
 * ----------
 */
Datum
RI_FKey_noaction_del(PG_FUNCTION_ARGS)
{
    /*
     * Check that this is a valid trigger call on the right time and event.
     */
    ri_CheckTrigger(fcinfo, "RI_FKey_noaction_del", RI_TRIGTYPE_DELETE);

    /*
     * Share code with RESTRICT case.
     */
    return ri_restrict_del((TriggerData *) fcinfo->context, true);
}

/* ----------
 * RI_FKey_restrict_del -
 *
 *  Restrict delete from PK table to rows unreferenced by foreign key.
 *
 *  The SQL standard intends that this referential action occur exactly when
 *  the delete is performed, rather than after.  This appears to be
 *  the only difference between "NO ACTION" and "RESTRICT".  In Postgres
 *  we still implement this as an AFTER trigger, but it's non-deferrable.
 * ----------
 */
Datum
RI_FKey_restrict_del(PG_FUNCTION_ARGS)
{
    /*
     * Check that this is a valid trigger call on the right time and event.
     */
    ri_CheckTrigger(fcinfo, "RI_FKey_restrict_del", RI_TRIGTYPE_DELETE);

    /*
     * Share code with NO ACTION case.
     */
    return ri_restrict_del((TriggerData *) fcinfo->context, false);
}

/* ----------
 * ri_restrict_del -
 *
 *  Common code for ON DELETE RESTRICT and ON DELETE NO ACTION.
 * ----------
 */
static Datum
ri_restrict_del(TriggerData *trigdata, bool is_no_action)
{
    const RI_ConstraintInfo *riinfo;
    Relation    fk_rel;
    Relation    pk_rel;
    HeapTuple   old_row;
    RI_QueryKey qkey;
    SPIPlanPtr  qplan;
    int         i;

    /*
     * Get arguments.
     */
    riinfo = ri_FetchConstraintInfo(trigdata->tg_trigger,
                                    trigdata->tg_relation, true);

    /*
     * Get the relation descriptors of the FK and PK tables and the old tuple.
     *
     * fk_rel is opened in RowShareLock mode since that's what our eventual
     * SELECT FOR KEY SHARE will get on it.
     */
    fk_rel = heap_open(riinfo->fk_relid, RowShareLock);
    pk_rel = trigdata->tg_relation;
    old_row = trigdata->tg_trigtuple;

    switch (riinfo->confmatchtype)
    {
            /* ----------
             * SQL:2008 15.17 <Execution of referential actions>
             *  General rules 9) a) iv):
             *      MATCH SIMPLE/FULL
             *          ... ON DELETE RESTRICT
             * ----------
             */
        case FKCONSTR_MATCH_SIMPLE:
        case FKCONSTR_MATCH_FULL:
            switch (ri_NullCheck(old_row, riinfo, true))
            {
                case RI_KEYS_ALL_NULL:
                case RI_KEYS_SOME_NULL:

                    /*
                     * No check needed - there cannot be any reference to old
                     * key if it contains a NULL
                     */
                    heap_close(fk_rel, RowShareLock);
                    return PointerGetDatum(NULL);

                case RI_KEYS_NONE_NULL:

                    /*
                     * Have a full qualified key - continue below
                     */
                    break;
            }

            /*
             * If another PK row now exists providing the old key values,
             * we should not do anything.  However, this check should only be
             * made in the NO ACTION case; in RESTRICT cases we don't wish to
             * allow another row to be substituted.
             */
            if (is_no_action &&
                ri_Check_Pk_Match(pk_rel, fk_rel, old_row, riinfo))
            {
                heap_close(fk_rel, RowShareLock);
                return PointerGetDatum(NULL);
            }

            if (SPI_connect() != SPI_OK_CONNECT)
                elog(ERROR, "SPI_connect failed");

            /*
             * Fetch or prepare a saved plan for the restrict delete lookup
             */
            ri_BuildQueryKey(&qkey, riinfo, RI_PLAN_RESTRICT_DEL_CHECKREF);

            if ((qplan = ri_FetchPreparedPlan(&qkey)) == NULL)
            {
                StringInfoData querybuf;
                char        fkrelname[MAX_QUOTED_REL_NAME_LEN];
                char        attname[MAX_QUOTED_NAME_LEN];
                char        paramname[16];
                const char *querysep;
                Oid         queryoids[RI_MAX_NUMKEYS];

                /* ----------
                 * The query string built is
                 *  SELECT 1 FROM ONLY <fktable> x WHERE $1 = fkatt1 [AND ...]
                 *         FOR KEY SHARE OF x
                 * The type id's for the $ parameters are those of the
                 * corresponding PK attributes.
                 * ----------
                 */
                initStringInfo(&querybuf);
                quoteRelationName(fkrelname, fk_rel);
                appendStringInfo(&querybuf, "SELECT 1 FROM ONLY %s x",
                                 fkrelname);
                querysep = "WHERE";
                for (i = 0; i < riinfo->nkeys; i++)
                {
                    Oid         pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
                    Oid         fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);

                    quoteOneName(attname,
                                 RIAttName(fk_rel, riinfo->fk_attnums[i]));
                    sprintf(paramname, "$%d", i + 1);
                    ri_GenerateQual(&querybuf, querysep,
                                    paramname, pk_type,
                                    riinfo->pf_eq_oprs[i],
                                    attname, fk_type);
                    querysep = "AND";
                    queryoids[i] = pk_type;
                }
                appendStringInfo(&querybuf, " FOR KEY SHARE OF x");

                /* Prepare and save the plan */
                qplan = ri_PlanCheck(querybuf.data, riinfo->nkeys, queryoids,
                                     &qkey, fk_rel, pk_rel, true);
            }

            /*
             * We have a plan now. Run it to check for existing references.
             */
            ri_PerformCheck(riinfo, &qkey, qplan,
                            fk_rel, pk_rel,
                            old_row, NULL,
                            true,       /* must detect new rows */
                            SPI_OK_SELECT);

            if (SPI_finish() != SPI_OK_FINISH)
                elog(ERROR, "SPI_finish failed");

            heap_close(fk_rel, RowShareLock);

            return PointerGetDatum(NULL);

            /*
             * Handle MATCH PARTIAL restrict delete.
             */
        case FKCONSTR_MATCH_PARTIAL:
            ereport(ERROR,
                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                     errmsg("MATCH PARTIAL not yet implemented")));
            return PointerGetDatum(NULL);

        default:
            elog(ERROR, "unrecognized confmatchtype: %d",
                 riinfo->confmatchtype);
            break;
    }

    /* Never reached */
    return PointerGetDatum(NULL);
}


/* ----------
 * RI_FKey_noaction_upd -
 *
 *  Give an error and roll back the current transaction if the
 *  update has resulted in a violation of the given referential
 *  integrity constraint.
 * ----------
 */
Datum
RI_FKey_noaction_upd(PG_FUNCTION_ARGS)
{
    /*
     * Check that this is a valid trigger call on the right time and event.
     */
    ri_CheckTrigger(fcinfo, "RI_FKey_noaction_upd", RI_TRIGTYPE_UPDATE);

    /*
     * Share code with RESTRICT case.
     */
    return ri_restrict_upd((TriggerData *) fcinfo->context, true);
}

/* ----------
 * RI_FKey_restrict_upd -
 *
 *  Restrict update of PK to rows unreferenced by foreign key.
 *
 *  The SQL standard intends that this referential action occur exactly when
 *  the update is performed, rather than after.  This appears to be
 *  the only difference between "NO ACTION" and "RESTRICT".  In Postgres
 *  we still implement this as an AFTER trigger, but it's non-deferrable.
 * ----------
 */
Datum
RI_FKey_restrict_upd(PG_FUNCTION_ARGS)
{
    /*
     * Check that this is a valid trigger call on the right time and event.
     */
    ri_CheckTrigger(fcinfo, "RI_FKey_restrict_upd", RI_TRIGTYPE_UPDATE);

    /*
     * Share code with NO ACTION case.
     */
    return ri_restrict_upd((TriggerData *) fcinfo->context, false);
}

/* ----------
 * ri_restrict_upd -
 *
 *  Common code for ON UPDATE RESTRICT and ON UPDATE NO ACTION.
 * ----------
 */
static Datum
ri_restrict_upd(TriggerData *trigdata, bool is_no_action)
{
    const RI_ConstraintInfo *riinfo;
    Relation    fk_rel;
    Relation    pk_rel;
    HeapTuple   new_row;
    HeapTuple   old_row;
    RI_QueryKey qkey;
    SPIPlanPtr  qplan;
    int         i;

    /*
     * Get arguments.
     */
    riinfo = ri_FetchConstraintInfo(trigdata->tg_trigger,
                                    trigdata->tg_relation, true);

    /*
     * Get the relation descriptors of the FK and PK tables and the new and
     * old tuple.
     *
     * fk_rel is opened in RowShareLock mode since that's what our eventual
     * SELECT FOR KEY SHARE will get on it.
     */
    fk_rel = heap_open(riinfo->fk_relid, RowShareLock);
    pk_rel = trigdata->tg_relation;
    new_row = trigdata->tg_newtuple;
    old_row = trigdata->tg_trigtuple;

    switch (riinfo->confmatchtype)
    {
            /* ----------
             * SQL:2008 15.17 <Execution of referential actions>
             *  General rules 10) a) iv):
             *      MATCH SIMPLE/FULL
             *          ... ON UPDATE RESTRICT
             * ----------
             */
        case FKCONSTR_MATCH_SIMPLE:
        case FKCONSTR_MATCH_FULL:
            switch (ri_NullCheck(old_row, riinfo, true))
            {
                case RI_KEYS_ALL_NULL:
                case RI_KEYS_SOME_NULL:

                    /*
                     * No check needed - there cannot be any reference to old
                     * key if it contains a NULL
                     */
                    heap_close(fk_rel, RowShareLock);
                    return PointerGetDatum(NULL);

                case RI_KEYS_NONE_NULL:

                    /*
                     * Have a full qualified key - continue below
                     */
                    break;
            }

            /*
             * No need to check anything if old and new keys are equal
             */
            if (ri_KeysEqual(pk_rel, old_row, new_row, riinfo, true))
            {
                heap_close(fk_rel, RowShareLock);
                return PointerGetDatum(NULL);
            }

            /*
             * If another PK row now exists providing the old key values,
             * we should not do anything.  However, this check should only be
             * made in the NO ACTION case; in RESTRICT cases we don't wish to
             * allow another row to be substituted.
             */
            if (is_no_action &&
                ri_Check_Pk_Match(pk_rel, fk_rel, old_row, riinfo))
            {
                heap_close(fk_rel, RowShareLock);
                return PointerGetDatum(NULL);
            }

            if (SPI_connect() != SPI_OK_CONNECT)
                elog(ERROR, "SPI_connect failed");

            /*
             * Fetch or prepare a saved plan for the restrict update lookup
             */
            ri_BuildQueryKey(&qkey, riinfo, RI_PLAN_RESTRICT_UPD_CHECKREF);

            if ((qplan = ri_FetchPreparedPlan(&qkey)) == NULL)
            {
                StringInfoData querybuf;
                char        fkrelname[MAX_QUOTED_REL_NAME_LEN];
                char        attname[MAX_QUOTED_NAME_LEN];
                char        paramname[16];
                const char *querysep;
                Oid         queryoids[RI_MAX_NUMKEYS];

                /* ----------
                 * The query string built is
                 *  SELECT 1 FROM ONLY <fktable> WHERE $1 = fkatt1 [AND ...]
                 * The type id's for the $ parameters are those of the
                 * corresponding PK attributes.
                 * ----------
                 */
                initStringInfo(&querybuf);
                quoteRelationName(fkrelname, fk_rel);
                appendStringInfo(&querybuf, "SELECT 1 FROM ONLY %s x",
                                 fkrelname);
                querysep = "WHERE";
                for (i = 0; i < riinfo->nkeys; i++)
                {
                    Oid         pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
                    Oid         fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);

                    quoteOneName(attname,
                                 RIAttName(fk_rel, riinfo->fk_attnums[i]));
                    sprintf(paramname, "$%d", i + 1);
                    ri_GenerateQual(&querybuf, querysep,
                                    paramname, pk_type,
                                    riinfo->pf_eq_oprs[i],
                                    attname, fk_type);
                    querysep = "AND";
                    queryoids[i] = pk_type;
                }
                appendStringInfo(&querybuf, " FOR KEY SHARE OF x");

                /* Prepare and save the plan */
                qplan = ri_PlanCheck(querybuf.data, riinfo->nkeys, queryoids,
                                     &qkey, fk_rel, pk_rel, true);
            }

            /*
             * We have a plan now. Run it to check for existing references.
             */
            ri_PerformCheck(riinfo, &qkey, qplan,
                            fk_rel, pk_rel,
                            old_row, NULL,
                            true,       /* must detect new rows */
                            SPI_OK_SELECT);

            if (SPI_finish() != SPI_OK_FINISH)
                elog(ERROR, "SPI_finish failed");

            heap_close(fk_rel, RowShareLock);

            return PointerGetDatum(NULL);

            /*
             * Handle MATCH PARTIAL restrict update.
             */
        case FKCONSTR_MATCH_PARTIAL:
            ereport(ERROR,
                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                     errmsg("MATCH PARTIAL not yet implemented")));
            return PointerGetDatum(NULL);

        default:
            elog(ERROR, "unrecognized confmatchtype: %d",
                 riinfo->confmatchtype);
            break;
    }

    /* Never reached */
    return PointerGetDatum(NULL);
}


/* ----------
 * RI_FKey_cascade_del -
 *
 *  Cascaded delete foreign key references at delete event on PK table.
 * ----------
 */
Datum
RI_FKey_cascade_del(PG_FUNCTION_ARGS)
{
    TriggerData *trigdata = (TriggerData *) fcinfo->context;
    const RI_ConstraintInfo *riinfo;
    Relation    fk_rel;
    Relation    pk_rel;
    HeapTuple   old_row;
    RI_QueryKey qkey;
    SPIPlanPtr  qplan;
    int         i;

    /*
     * Check that this is a valid trigger call on the right time and event.
     */
    ri_CheckTrigger(fcinfo, "RI_FKey_cascade_del", RI_TRIGTYPE_DELETE);

    /*
     * Get arguments.
     */
    riinfo = ri_FetchConstraintInfo(trigdata->tg_trigger,
                                    trigdata->tg_relation, true);

    /*
     * Get the relation descriptors of the FK and PK tables and the old tuple.
     *
     * fk_rel is opened in RowExclusiveLock mode since that's what our
     * eventual DELETE will get on it.
     */
    fk_rel = heap_open(riinfo->fk_relid, RowExclusiveLock);
    pk_rel = trigdata->tg_relation;
    old_row = trigdata->tg_trigtuple;

    switch (riinfo->confmatchtype)
    {
            /* ----------
             * SQL:2008 15.17 <Execution of referential actions>
             *  General rules 9) a) i):
             *      MATCH SIMPLE/FULL
             *          ... ON DELETE CASCADE
             * ----------
             */
        case FKCONSTR_MATCH_SIMPLE:
        case FKCONSTR_MATCH_FULL:
            switch (ri_NullCheck(old_row, riinfo, true))
            {
                case RI_KEYS_ALL_NULL:
                case RI_KEYS_SOME_NULL:

                    /*
                     * No check needed - there cannot be any reference to old
                     * key if it contains a NULL
                     */
                    heap_close(fk_rel, RowExclusiveLock);
                    return PointerGetDatum(NULL);

                case RI_KEYS_NONE_NULL:

                    /*
                     * Have a full qualified key - continue below
                     */
                    break;
            }

            if (SPI_connect() != SPI_OK_CONNECT)
                elog(ERROR, "SPI_connect failed");

            /*
             * Fetch or prepare a saved plan for the cascaded delete
             */
            ri_BuildQueryKey(&qkey, riinfo, RI_PLAN_CASCADE_DEL_DODELETE);

            if ((qplan = ri_FetchPreparedPlan(&qkey)) == NULL)
            {
                StringInfoData querybuf;
                char        fkrelname[MAX_QUOTED_REL_NAME_LEN];
                char        attname[MAX_QUOTED_NAME_LEN];
                char        paramname[16];
                const char *querysep;
                Oid         queryoids[RI_MAX_NUMKEYS];

                /* ----------
                 * The query string built is
                 *  DELETE FROM ONLY <fktable> WHERE $1 = fkatt1 [AND ...]
                 * The type id's for the $ parameters are those of the
                 * corresponding PK attributes.
                 * ----------
                 */
                initStringInfo(&querybuf);
                quoteRelationName(fkrelname, fk_rel);
                appendStringInfo(&querybuf, "DELETE FROM ONLY %s", fkrelname);
                querysep = "WHERE";
                for (i = 0; i < riinfo->nkeys; i++)
                {
                    Oid         pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
                    Oid         fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);

                    quoteOneName(attname,
                                 RIAttName(fk_rel, riinfo->fk_attnums[i]));
                    sprintf(paramname, "$%d", i + 1);
                    ri_GenerateQual(&querybuf, querysep,
                                    paramname, pk_type,
                                    riinfo->pf_eq_oprs[i],
                                    attname, fk_type);
                    querysep = "AND";
                    queryoids[i] = pk_type;
                }

                /* Prepare and save the plan */
                qplan = ri_PlanCheck(querybuf.data, riinfo->nkeys, queryoids,
                                     &qkey, fk_rel, pk_rel, true);
            }

            /*
             * We have a plan now. Build up the arguments from the key values
             * in the deleted PK tuple and delete the referencing rows
             */
            ri_PerformCheck(riinfo, &qkey, qplan,
                            fk_rel, pk_rel,
                            old_row, NULL,
                            true,       /* must detect new rows */
                            SPI_OK_DELETE);

            if (SPI_finish() != SPI_OK_FINISH)
                elog(ERROR, "SPI_finish failed");

            heap_close(fk_rel, RowExclusiveLock);

            return PointerGetDatum(NULL);

            /*
             * Handle MATCH PARTIAL cascaded delete.
             */
        case FKCONSTR_MATCH_PARTIAL:
            ereport(ERROR,
                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                     errmsg("MATCH PARTIAL not yet implemented")));
            return PointerGetDatum(NULL);

        default:
            elog(ERROR, "unrecognized confmatchtype: %d",
                 riinfo->confmatchtype);
            break;
    }

    /* Never reached */
    return PointerGetDatum(NULL);
}


/* ----------
 * RI_FKey_cascade_upd -
 *
 *  Cascaded update foreign key references at update event on PK table.
 * ----------
 */
Datum
RI_FKey_cascade_upd(PG_FUNCTION_ARGS)
{
    TriggerData *trigdata = (TriggerData *) fcinfo->context;
    const RI_ConstraintInfo *riinfo;
    Relation    fk_rel;
    Relation    pk_rel;
    HeapTuple   new_row;
    HeapTuple   old_row;
    RI_QueryKey qkey;
    SPIPlanPtr  qplan;
    int         i;
    int         j;

    /*
     * Check that this is a valid trigger call on the right time and event.
     */
    ri_CheckTrigger(fcinfo, "RI_FKey_cascade_upd", RI_TRIGTYPE_UPDATE);

    /*
     * Get arguments.
     */
    riinfo = ri_FetchConstraintInfo(trigdata->tg_trigger,
                                    trigdata->tg_relation, true);

    /*
     * Get the relation descriptors of the FK and PK tables and the new and
     * old tuple.
     *
     * fk_rel is opened in RowExclusiveLock mode since that's what our
     * eventual UPDATE will get on it.
     */
    fk_rel = heap_open(riinfo->fk_relid, RowExclusiveLock);
    pk_rel = trigdata->tg_relation;
    new_row = trigdata->tg_newtuple;
    old_row = trigdata->tg_trigtuple;

    switch (riinfo->confmatchtype)
    {
            /* ----------
             * SQL:2008 15.17 <Execution of referential actions>
             *  General rules 10) a) i):
             *      MATCH SIMPLE/FULL
             *          ... ON UPDATE CASCADE
             * ----------
             */
        case FKCONSTR_MATCH_SIMPLE:
        case FKCONSTR_MATCH_FULL:
            switch (ri_NullCheck(old_row, riinfo, true))
            {
                case RI_KEYS_ALL_NULL:
                case RI_KEYS_SOME_NULL:

                    /*
                     * No check needed - there cannot be any reference to old
                     * key if it contains a NULL
                     */
                    heap_close(fk_rel, RowExclusiveLock);
                    return PointerGetDatum(NULL);

                case RI_KEYS_NONE_NULL:

                    /*
                     * Have a full qualified key - continue below
                     */
                    break;
            }

            /*
             * No need to do anything if old and new keys are equal
             */
            if (ri_KeysEqual(pk_rel, old_row, new_row, riinfo, true))
            {
                heap_close(fk_rel, RowExclusiveLock);
                return PointerGetDatum(NULL);
            }

            if (SPI_connect() != SPI_OK_CONNECT)
                elog(ERROR, "SPI_connect failed");

            /*
             * Fetch or prepare a saved plan for the cascaded update
             */
            ri_BuildQueryKey(&qkey, riinfo, RI_PLAN_CASCADE_UPD_DOUPDATE);

            if ((qplan = ri_FetchPreparedPlan(&qkey)) == NULL)
            {
                StringInfoData querybuf;
                StringInfoData qualbuf;
                char        fkrelname[MAX_QUOTED_REL_NAME_LEN];
                char        attname[MAX_QUOTED_NAME_LEN];
                char        paramname[16];
                const char *querysep;
                const char *qualsep;
                Oid         queryoids[RI_MAX_NUMKEYS * 2];

                /* ----------
                 * The query string built is
                 *  UPDATE ONLY <fktable> SET fkatt1 = $1 [, ...]
                 *          WHERE $n = fkatt1 [AND ...]
                 * The type id's for the $ parameters are those of the
                 * corresponding PK attributes.  Note that we are assuming
                 * there is an assignment cast from the PK to the FK type;
                 * else the parser will fail.
                 * ----------
                 */
                initStringInfo(&querybuf);
                initStringInfo(&qualbuf);
                quoteRelationName(fkrelname, fk_rel);
                appendStringInfo(&querybuf, "UPDATE ONLY %s SET", fkrelname);
                querysep = "";
                qualsep = "WHERE";
                for (i = 0, j = riinfo->nkeys; i < riinfo->nkeys; i++, j++)
                {
                    Oid         pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
                    Oid         fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);

                    quoteOneName(attname,
                                 RIAttName(fk_rel, riinfo->fk_attnums[i]));
                    appendStringInfo(&querybuf,
                                     "%s %s = $%d",
                                     querysep, attname, i + 1);
                    sprintf(paramname, "$%d", j + 1);
                    ri_GenerateQual(&qualbuf, qualsep,
                                    paramname, pk_type,
                                    riinfo->pf_eq_oprs[i],
                                    attname, fk_type);
                    querysep = ",";
                    qualsep = "AND";
                    queryoids[i] = pk_type;
                    queryoids[j] = pk_type;
                }
                appendStringInfoString(&querybuf, qualbuf.data);

                /* Prepare and save the plan */
                qplan = ri_PlanCheck(querybuf.data, riinfo->nkeys * 2, queryoids,
                                     &qkey, fk_rel, pk_rel, true);
            }

            /*
             * We have a plan now. Run it to update the existing references.
             */
            ri_PerformCheck(riinfo, &qkey, qplan,
                            fk_rel, pk_rel,
                            old_row, new_row,
                            true,       /* must detect new rows */
                            SPI_OK_UPDATE);

            if (SPI_finish() != SPI_OK_FINISH)
                elog(ERROR, "SPI_finish failed");

            heap_close(fk_rel, RowExclusiveLock);

            return PointerGetDatum(NULL);

            /*
             * Handle MATCH PARTIAL cascade update.
             */
        case FKCONSTR_MATCH_PARTIAL:
            ereport(ERROR,
                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                     errmsg("MATCH PARTIAL not yet implemented")));
            return PointerGetDatum(NULL);

        default:
            elog(ERROR, "unrecognized confmatchtype: %d",
                 riinfo->confmatchtype);
            break;
    }

    /* Never reached */
    return PointerGetDatum(NULL);
}


/* ----------
 * RI_FKey_setnull_del -
 *
 *  Set foreign key references to NULL values at delete event on PK table.
 * ----------
 */
Datum
RI_FKey_setnull_del(PG_FUNCTION_ARGS)
{
    TriggerData *trigdata = (TriggerData *) fcinfo->context;
    const RI_ConstraintInfo *riinfo;
    Relation    fk_rel;
    Relation    pk_rel;
    HeapTuple   old_row;
    RI_QueryKey qkey;
    SPIPlanPtr  qplan;
    int         i;

    /*
     * Check that this is a valid trigger call on the right time and event.
     */
    ri_CheckTrigger(fcinfo, "RI_FKey_setnull_del", RI_TRIGTYPE_DELETE);

    /*
     * Get arguments.
     */
    riinfo = ri_FetchConstraintInfo(trigdata->tg_trigger,
                                    trigdata->tg_relation, true);

    /*
     * Get the relation descriptors of the FK and PK tables and the old tuple.
     *
     * fk_rel is opened in RowExclusiveLock mode since that's what our
     * eventual UPDATE will get on it.
     */
    fk_rel = heap_open(riinfo->fk_relid, RowExclusiveLock);
    pk_rel = trigdata->tg_relation;
    old_row = trigdata->tg_trigtuple;

    switch (riinfo->confmatchtype)
    {
            /* ----------
             * SQL:2008 15.17 <Execution of referential actions>
             *  General rules 9) a) ii):
             *      MATCH SIMPLE/FULL
             *          ... ON DELETE SET NULL
             * ----------
             */
        case FKCONSTR_MATCH_SIMPLE:
        case FKCONSTR_MATCH_FULL:
            switch (ri_NullCheck(old_row, riinfo, true))
            {
                case RI_KEYS_ALL_NULL:
                case RI_KEYS_SOME_NULL:

                    /*
                     * No check needed - there cannot be any reference to old
                     * key if it contains a NULL
                     */
                    heap_close(fk_rel, RowExclusiveLock);
                    return PointerGetDatum(NULL);

                case RI_KEYS_NONE_NULL:

                    /*
                     * Have a full qualified key - continue below
                     */
                    break;
            }

            if (SPI_connect() != SPI_OK_CONNECT)
                elog(ERROR, "SPI_connect failed");

            /*
             * Fetch or prepare a saved plan for the set null delete operation
             */
            ri_BuildQueryKey(&qkey, riinfo, RI_PLAN_SETNULL_DEL_DOUPDATE);

            if ((qplan = ri_FetchPreparedPlan(&qkey)) == NULL)
            {
                StringInfoData querybuf;
                StringInfoData qualbuf;
                char        fkrelname[MAX_QUOTED_REL_NAME_LEN];
                char        attname[MAX_QUOTED_NAME_LEN];
                char        paramname[16];
                const char *querysep;
                const char *qualsep;
                Oid         queryoids[RI_MAX_NUMKEYS];

                /* ----------
                 * The query string built is
                 *  UPDATE ONLY <fktable> SET fkatt1 = NULL [, ...]
                 *          WHERE $1 = fkatt1 [AND ...]
                 * The type id's for the $ parameters are those of the
                 * corresponding PK attributes.
                 * ----------
                 */
                initStringInfo(&querybuf);
                initStringInfo(&qualbuf);
                quoteRelationName(fkrelname, fk_rel);
                appendStringInfo(&querybuf, "UPDATE ONLY %s SET", fkrelname);
                querysep = "";
                qualsep = "WHERE";
                for (i = 0; i < riinfo->nkeys; i++)
                {
                    Oid         pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
                    Oid         fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);

                    quoteOneName(attname,
                                 RIAttName(fk_rel, riinfo->fk_attnums[i]));
                    appendStringInfo(&querybuf,
                                     "%s %s = NULL",
                                     querysep, attname);
                    sprintf(paramname, "$%d", i + 1);
                    ri_GenerateQual(&qualbuf, qualsep,
                                    paramname, pk_type,
                                    riinfo->pf_eq_oprs[i],
                                    attname, fk_type);
                    querysep = ",";
                    qualsep = "AND";
                    queryoids[i] = pk_type;
                }
                appendStringInfoString(&querybuf, qualbuf.data);

                /* Prepare and save the plan */
                qplan = ri_PlanCheck(querybuf.data, riinfo->nkeys, queryoids,
                                     &qkey, fk_rel, pk_rel, true);
            }

            /*
             * We have a plan now. Run it to check for existing references.
             */
            ri_PerformCheck(riinfo, &qkey, qplan,
                            fk_rel, pk_rel,
                            old_row, NULL,
                            true,       /* must detect new rows */
                            SPI_OK_UPDATE);

            if (SPI_finish() != SPI_OK_FINISH)
                elog(ERROR, "SPI_finish failed");

            heap_close(fk_rel, RowExclusiveLock);

            return PointerGetDatum(NULL);

            /*
             * Handle MATCH PARTIAL set null delete.
             */
        case FKCONSTR_MATCH_PARTIAL:
            ereport(ERROR,
                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                     errmsg("MATCH PARTIAL not yet implemented")));
            return PointerGetDatum(NULL);

        default:
            elog(ERROR, "unrecognized confmatchtype: %d",
                 riinfo->confmatchtype);
            break;
    }

    /* Never reached */
    return PointerGetDatum(NULL);
}


/* ----------
 * RI_FKey_setnull_upd -
 *
 *  Set foreign key references to NULL at update event on PK table.
 * ----------
 */
Datum
RI_FKey_setnull_upd(PG_FUNCTION_ARGS)
{
    TriggerData *trigdata = (TriggerData *) fcinfo->context;
    const RI_ConstraintInfo *riinfo;
    Relation    fk_rel;
    Relation    pk_rel;
    HeapTuple   new_row;
    HeapTuple   old_row;
    RI_QueryKey qkey;
    SPIPlanPtr  qplan;
    int         i;

    /*
     * Check that this is a valid trigger call on the right time and event.
     */
    ri_CheckTrigger(fcinfo, "RI_FKey_setnull_upd", RI_TRIGTYPE_UPDATE);

    /*
     * Get arguments.
     */
    riinfo = ri_FetchConstraintInfo(trigdata->tg_trigger,
                                    trigdata->tg_relation, true);

    /*
     * Get the relation descriptors of the FK and PK tables and the old tuple.
     *
     * fk_rel is opened in RowExclusiveLock mode since that's what our
     * eventual UPDATE will get on it.
     */
    fk_rel = heap_open(riinfo->fk_relid, RowExclusiveLock);
    pk_rel = trigdata->tg_relation;
    new_row = trigdata->tg_newtuple;
    old_row = trigdata->tg_trigtuple;

    switch (riinfo->confmatchtype)
    {
            /* ----------
             * SQL:2008 15.17 <Execution of referential actions>
             *  General rules 10) a) ii):
             *      MATCH SIMPLE/FULL
             *          ... ON UPDATE SET NULL
             * ----------
             */
        case FKCONSTR_MATCH_SIMPLE:
        case FKCONSTR_MATCH_FULL:
            switch (ri_NullCheck(old_row, riinfo, true))
            {
                case RI_KEYS_ALL_NULL:
                case RI_KEYS_SOME_NULL:

                    /*
                     * No check needed - there cannot be any reference to old
                     * key if it contains a NULL
                     */
                    heap_close(fk_rel, RowExclusiveLock);
                    return PointerGetDatum(NULL);

                case RI_KEYS_NONE_NULL:

                    /*
                     * Have a full qualified key - continue below
                     */
                    break;
            }

            /*
             * No need to do anything if old and new keys are equal
             */
            if (ri_KeysEqual(pk_rel, old_row, new_row, riinfo, true))
            {
                heap_close(fk_rel, RowExclusiveLock);
                return PointerGetDatum(NULL);
            }

            if (SPI_connect() != SPI_OK_CONNECT)
                elog(ERROR, "SPI_connect failed");

            /*
             * Fetch or prepare a saved plan for the set null update operation
             */
            ri_BuildQueryKey(&qkey, riinfo, RI_PLAN_SETNULL_UPD_DOUPDATE);

            if ((qplan = ri_FetchPreparedPlan(&qkey)) == NULL)
            {
                StringInfoData querybuf;
                StringInfoData qualbuf;
                char        fkrelname[MAX_QUOTED_REL_NAME_LEN];
                char        attname[MAX_QUOTED_NAME_LEN];
                char        paramname[16];
                const char *querysep;
                const char *qualsep;
                Oid         queryoids[RI_MAX_NUMKEYS];

                /* ----------
                 * The query string built is
                 *  UPDATE ONLY <fktable> SET fkatt1 = NULL [, ...]
                 *          WHERE $1 = fkatt1 [AND ...]
                 * The type id's for the $ parameters are those of the
                 * corresponding PK attributes.
                 * ----------
                 */
                initStringInfo(&querybuf);
                initStringInfo(&qualbuf);
                quoteRelationName(fkrelname, fk_rel);
                appendStringInfo(&querybuf, "UPDATE ONLY %s SET", fkrelname);
                querysep = "";
                qualsep = "WHERE";
                for (i = 0; i < riinfo->nkeys; i++)
                {
                    Oid         pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
                    Oid         fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);

                    quoteOneName(attname,
                                 RIAttName(fk_rel, riinfo->fk_attnums[i]));
                    appendStringInfo(&querybuf,
                                     "%s %s = NULL",
                                     querysep, attname);
                    sprintf(paramname, "$%d", i + 1);
                    ri_GenerateQual(&qualbuf, qualsep,
                                    paramname, pk_type,
                                    riinfo->pf_eq_oprs[i],
                                    attname, fk_type);
                    querysep = ",";
                    qualsep = "AND";
                    queryoids[i] = pk_type;
                }
                appendStringInfoString(&querybuf, qualbuf.data);

                /* Prepare and save the plan */
                qplan = ri_PlanCheck(querybuf.data, riinfo->nkeys, queryoids,
                                     &qkey, fk_rel, pk_rel, true);
            }

            /*
             * We have a plan now. Run it to update the existing references.
             */
            ri_PerformCheck(riinfo, &qkey, qplan,
                            fk_rel, pk_rel,
                            old_row, NULL,
                            true,       /* must detect new rows */
                            SPI_OK_UPDATE);

            if (SPI_finish() != SPI_OK_FINISH)
                elog(ERROR, "SPI_finish failed");

            heap_close(fk_rel, RowExclusiveLock);

            return PointerGetDatum(NULL);

            /*
             * Handle MATCH PARTIAL set null update.
             */
        case FKCONSTR_MATCH_PARTIAL:
            ereport(ERROR,
                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                     errmsg("MATCH PARTIAL not yet implemented")));
            return PointerGetDatum(NULL);

        default:
            elog(ERROR, "unrecognized confmatchtype: %d",
                 riinfo->confmatchtype);
            break;
    }

    /* Never reached */
    return PointerGetDatum(NULL);
}


/* ----------
 * RI_FKey_setdefault_del -
 *
 *  Set foreign key references to defaults at delete event on PK table.
 * ----------
 */
Datum
RI_FKey_setdefault_del(PG_FUNCTION_ARGS)
{
    TriggerData *trigdata = (TriggerData *) fcinfo->context;
    const RI_ConstraintInfo *riinfo;
    Relation    fk_rel;
    Relation    pk_rel;
    HeapTuple   old_row;
    RI_QueryKey qkey;
    SPIPlanPtr  qplan;

    /*
     * Check that this is a valid trigger call on the right time and event.
     */
    ri_CheckTrigger(fcinfo, "RI_FKey_setdefault_del", RI_TRIGTYPE_DELETE);

    /*
     * Get arguments.
     */
    riinfo = ri_FetchConstraintInfo(trigdata->tg_trigger,
                                    trigdata->tg_relation, true);

    /*
     * Get the relation descriptors of the FK and PK tables and the old tuple.
     *
     * fk_rel is opened in RowExclusiveLock mode since that's what our
     * eventual UPDATE will get on it.
     */
    fk_rel = heap_open(riinfo->fk_relid, RowExclusiveLock);
    pk_rel = trigdata->tg_relation;
    old_row = trigdata->tg_trigtuple;

    switch (riinfo->confmatchtype)
    {
            /* ----------
             * SQL:2008 15.17 <Execution of referential actions>
             *  General rules 9) a) iii):
             *      MATCH SIMPLE/FULL
             *          ... ON DELETE SET DEFAULT
             * ----------
             */
        case FKCONSTR_MATCH_SIMPLE:
        case FKCONSTR_MATCH_FULL:
            switch (ri_NullCheck(old_row, riinfo, true))
            {
                case RI_KEYS_ALL_NULL:
                case RI_KEYS_SOME_NULL:

                    /*
                     * No check needed - there cannot be any reference to old
                     * key if it contains a NULL
                     */
                    heap_close(fk_rel, RowExclusiveLock);
                    return PointerGetDatum(NULL);

                case RI_KEYS_NONE_NULL:

                    /*
                     * Have a full qualified key - continue below
                     */
                    break;
            }

            if (SPI_connect() != SPI_OK_CONNECT)
                elog(ERROR, "SPI_connect failed");

            /*
             * Fetch or prepare a saved plan for the set default delete
             * operation
             */
            ri_BuildQueryKey(&qkey, riinfo, RI_PLAN_SETDEFAULT_DEL_DOUPDATE);

            if ((qplan = ri_FetchPreparedPlan(&qkey)) == NULL)
            {
                StringInfoData querybuf;
                StringInfoData qualbuf;
                char        fkrelname[MAX_QUOTED_REL_NAME_LEN];
                char        attname[MAX_QUOTED_NAME_LEN];
                char        paramname[16];
                const char *querysep;
                const char *qualsep;
                Oid         queryoids[RI_MAX_NUMKEYS];
                int         i;

                /* ----------
                 * The query string built is
                 *  UPDATE ONLY <fktable> SET fkatt1 = DEFAULT [, ...]
                 *          WHERE $1 = fkatt1 [AND ...]
                 * The type id's for the $ parameters are those of the
                 * corresponding PK attributes.
                 * ----------
                 */
                initStringInfo(&querybuf);
                initStringInfo(&qualbuf);
                quoteRelationName(fkrelname, fk_rel);
                appendStringInfo(&querybuf, "UPDATE ONLY %s SET", fkrelname);
                querysep = "";
                qualsep = "WHERE";
                for (i = 0; i < riinfo->nkeys; i++)
                {
                    Oid         pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
                    Oid         fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);

                    quoteOneName(attname,
                                 RIAttName(fk_rel, riinfo->fk_attnums[i]));
                    appendStringInfo(&querybuf,
                                     "%s %s = DEFAULT",
                                     querysep, attname);
                    sprintf(paramname, "$%d", i + 1);
                    ri_GenerateQual(&qualbuf, qualsep,
                                    paramname, pk_type,
                                    riinfo->pf_eq_oprs[i],
                                    attname, fk_type);
                    querysep = ",";
                    qualsep = "AND";
                    queryoids[i] = pk_type;
                }
                appendStringInfoString(&querybuf, qualbuf.data);

                /* Prepare and save the plan */
                qplan = ri_PlanCheck(querybuf.data, riinfo->nkeys, queryoids,
                                     &qkey, fk_rel, pk_rel, true);
            }

            /*
             * We have a plan now. Run it to update the existing references.
             */
            ri_PerformCheck(riinfo, &qkey, qplan,
                            fk_rel, pk_rel,
                            old_row, NULL,
                            true,       /* must detect new rows */
                            SPI_OK_UPDATE);

            if (SPI_finish() != SPI_OK_FINISH)
                elog(ERROR, "SPI_finish failed");

            heap_close(fk_rel, RowExclusiveLock);

            /*
             * If we just deleted the PK row whose key was equal to the FK
             * columns' default values, and a referencing row exists in the FK
             * table, we would have updated that row to the same values it
             * already had --- and RI_FKey_fk_upd_check_required would hence
             * believe no check is necessary.  So we need to do another lookup
             * now and in case a reference still exists, abort the operation.
             * That is already implemented in the NO ACTION trigger, so just
             * run it.  (This recheck is only needed in the SET DEFAULT case,
             * since CASCADE would remove such rows, while SET NULL is certain
             * to result in rows that satisfy the FK constraint.)
             */
            RI_FKey_noaction_del(fcinfo);

            return PointerGetDatum(NULL);

            /*
             * Handle MATCH PARTIAL set default delete.
             */
        case FKCONSTR_MATCH_PARTIAL:
            ereport(ERROR,
                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                     errmsg("MATCH PARTIAL not yet implemented")));
            return PointerGetDatum(NULL);

        default:
            elog(ERROR, "unrecognized confmatchtype: %d",
                 riinfo->confmatchtype);
            break;
    }

    /* Never reached */
    return PointerGetDatum(NULL);
}


/* ----------
 * RI_FKey_setdefault_upd -
 *
 *  Set foreign key references to defaults at update event on PK table.
 * ----------
 */
Datum
RI_FKey_setdefault_upd(PG_FUNCTION_ARGS)
{
    TriggerData *trigdata = (TriggerData *) fcinfo->context;
    const RI_ConstraintInfo *riinfo;
    Relation    fk_rel;
    Relation    pk_rel;
    HeapTuple   new_row;
    HeapTuple   old_row;
    RI_QueryKey qkey;
    SPIPlanPtr  qplan;

    /*
     * Check that this is a valid trigger call on the right time and event.
     */
    ri_CheckTrigger(fcinfo, "RI_FKey_setdefault_upd", RI_TRIGTYPE_UPDATE);

    /*
     * Get arguments.
     */
    riinfo = ri_FetchConstraintInfo(trigdata->tg_trigger,
                                    trigdata->tg_relation, true);

    /*
     * Get the relation descriptors of the FK and PK tables and the old tuple.
     *
     * fk_rel is opened in RowExclusiveLock mode since that's what our
     * eventual UPDATE will get on it.
     */
    fk_rel = heap_open(riinfo->fk_relid, RowExclusiveLock);
    pk_rel = trigdata->tg_relation;
    new_row = trigdata->tg_newtuple;
    old_row = trigdata->tg_trigtuple;

    switch (riinfo->confmatchtype)
    {
            /* ----------
             * SQL:2008 15.17 <Execution of referential actions>
             *  General rules 10) a) iii):
             *      MATCH SIMPLE/FULL
             *          ... ON UPDATE SET DEFAULT
             * ----------
             */
        case FKCONSTR_MATCH_SIMPLE:
        case FKCONSTR_MATCH_FULL:
            switch (ri_NullCheck(old_row, riinfo, true))
            {
                case RI_KEYS_ALL_NULL:
                case RI_KEYS_SOME_NULL:

                    /*
                     * No check needed - there cannot be any reference to old
                     * key if it contains a NULL
                     */
                    heap_close(fk_rel, RowExclusiveLock);
                    return PointerGetDatum(NULL);

                case RI_KEYS_NONE_NULL:

                    /*
                     * Have a full qualified key - continue below
                     */
                    break;
            }

            /*
             * No need to do anything if old and new keys are equal
             */
            if (ri_KeysEqual(pk_rel, old_row, new_row, riinfo, true))
            {
                heap_close(fk_rel, RowExclusiveLock);
                return PointerGetDatum(NULL);
            }

            if (SPI_connect() != SPI_OK_CONNECT)
                elog(ERROR, "SPI_connect failed");

            /*
             * Fetch or prepare a saved plan for the set default update
             * operation
             */
            ri_BuildQueryKey(&qkey, riinfo, RI_PLAN_SETDEFAULT_UPD_DOUPDATE);

            if ((qplan = ri_FetchPreparedPlan(&qkey)) == NULL)
            {
                StringInfoData querybuf;
                StringInfoData qualbuf;
                char        fkrelname[MAX_QUOTED_REL_NAME_LEN];
                char        attname[MAX_QUOTED_NAME_LEN];
                char        paramname[16];
                const char *querysep;
                const char *qualsep;
                Oid         queryoids[RI_MAX_NUMKEYS];
                int         i;

                /* ----------
                 * The query string built is
                 *  UPDATE ONLY <fktable> SET fkatt1 = DEFAULT [, ...]
                 *          WHERE $1 = fkatt1 [AND ...]
                 * The type id's for the $ parameters are those of the
                 * corresponding PK attributes.
                 * ----------
                 */
                initStringInfo(&querybuf);
                initStringInfo(&qualbuf);
                quoteRelationName(fkrelname, fk_rel);
                appendStringInfo(&querybuf, "UPDATE ONLY %s SET", fkrelname);
                querysep = "";
                qualsep = "WHERE";
                for (i = 0; i < riinfo->nkeys; i++)
                {
                    Oid         pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
                    Oid         fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);

                    quoteOneName(attname,
                                 RIAttName(fk_rel, riinfo->fk_attnums[i]));
                    appendStringInfo(&querybuf,
                                     "%s %s = DEFAULT",
                                     querysep, attname);
                    sprintf(paramname, "$%d", i + 1);
                    ri_GenerateQual(&qualbuf, qualsep,
                                    paramname, pk_type,
                                    riinfo->pf_eq_oprs[i],
                                    attname, fk_type);
                    querysep = ",";
                    qualsep = "AND";
                    queryoids[i] = pk_type;
                }
                appendStringInfoString(&querybuf, qualbuf.data);

                /* Prepare and save the plan */
                qplan = ri_PlanCheck(querybuf.data, riinfo->nkeys, queryoids,
                                     &qkey, fk_rel, pk_rel, true);
            }

            /*
             * We have a plan now. Run it to update the existing references.
             */
            ri_PerformCheck(riinfo, &qkey, qplan,
                            fk_rel, pk_rel,
                            old_row, NULL,
                            true,       /* must detect new rows */
                            SPI_OK_UPDATE);

            if (SPI_finish() != SPI_OK_FINISH)
                elog(ERROR, "SPI_finish failed");

            heap_close(fk_rel, RowExclusiveLock);

            /*
             * If we just updated the PK row whose key was equal to the FK
             * columns' default values, and a referencing row exists in the FK
             * table, we would have updated that row to the same values it
             * already had --- and RI_FKey_fk_upd_check_required would hence
             * believe no check is necessary.  So we need to do another lookup
             * now and in case a reference still exists, abort the operation.
             * That is already implemented in the NO ACTION trigger, so just
             * run it.  (This recheck is only needed in the SET DEFAULT case,
             * since CASCADE must change the FK key values, while SET NULL is
             * certain to result in rows that satisfy the FK constraint.)
             */
            RI_FKey_noaction_upd(fcinfo);

            return PointerGetDatum(NULL);

            /*
             * Handle MATCH PARTIAL set default update.
             */
        case FKCONSTR_MATCH_PARTIAL:
            ereport(ERROR,
                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                     errmsg("MATCH PARTIAL not yet implemented")));
            return PointerGetDatum(NULL);

        default:
            elog(ERROR, "unrecognized confmatchtype: %d",
                 riinfo->confmatchtype);
            break;
    }

    /* Never reached */
    return PointerGetDatum(NULL);
}


/* ----------
 * RI_FKey_pk_upd_check_required -
 *
 *  Check if we really need to fire the RI trigger for an update to a PK
 *  relation.  This is called by the AFTER trigger queue manager to see if
 *  it can skip queuing an instance of an RI trigger.  Returns TRUE if the
 *  trigger must be fired, FALSE if we can prove the constraint will still
 *  be satisfied.
 * ----------
 */
bool
RI_FKey_pk_upd_check_required(Trigger *trigger, Relation pk_rel,
                              HeapTuple old_row, HeapTuple new_row)
{
    const RI_ConstraintInfo *riinfo;

    /*
     * Get arguments.
     */
    riinfo = ri_FetchConstraintInfo(trigger, pk_rel, true);

    switch (riinfo->confmatchtype)
    {
        case FKCONSTR_MATCH_SIMPLE:
        case FKCONSTR_MATCH_FULL:

            /*
             * If any old key value is NULL, the row could not have been
             * referenced by an FK row, so no check is needed.
             */
            if (ri_NullCheck(old_row, riinfo, true) != RI_KEYS_NONE_NULL)
                return false;

            /* If all old and new key values are equal, no check is needed */
            if (ri_KeysEqual(pk_rel, old_row, new_row, riinfo, true))
                return false;

            /* Else we need to fire the trigger. */
            return true;

            /* Handle MATCH PARTIAL check. */
        case FKCONSTR_MATCH_PARTIAL:
            ereport(ERROR,
                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                     errmsg("MATCH PARTIAL not yet implemented")));
            break;

        default:
            elog(ERROR, "unrecognized confmatchtype: %d",
                 riinfo->confmatchtype);
            break;
    }

    /* Never reached */
    return false;
}

/* ----------
 * RI_FKey_fk_upd_check_required -
 *
 *  Check if we really need to fire the RI trigger for an update to an FK
 *  relation.  This is called by the AFTER trigger queue manager to see if
 *  it can skip queuing an instance of an RI trigger.  Returns TRUE if the
 *  trigger must be fired, FALSE if we can prove the constraint will still
 *  be satisfied.
 * ----------
 */
bool
RI_FKey_fk_upd_check_required(Trigger *trigger, Relation fk_rel,
                              HeapTuple old_row, HeapTuple new_row)
{
    const RI_ConstraintInfo *riinfo;

    /*
     * Get arguments.
     */
    riinfo = ri_FetchConstraintInfo(trigger, fk_rel, false);

    switch (riinfo->confmatchtype)
    {
        case FKCONSTR_MATCH_SIMPLE:
            /*
             * If any new key value is NULL, the row must satisfy the
             * constraint, so no check is needed.
             */
            if (ri_NullCheck(new_row, riinfo, false) != RI_KEYS_NONE_NULL)
                return false;

            /*
             * If the original row was inserted by our own transaction, we
             * must fire the trigger whether or not the keys are equal.  This
             * is because our UPDATE will invalidate the INSERT so that the
             * INSERT RI trigger will not do anything; so we had better do the
             * UPDATE check.  (We could skip this if we knew the INSERT
             * trigger already fired, but there is no easy way to know that.)
             */
            if (TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmin(old_row->t_data)))
                return true;

            /* If all old and new key values are equal, no check is needed */
            if (ri_KeysEqual(fk_rel, old_row, new_row, riinfo, false))
                return false;

            /* Else we need to fire the trigger. */
            return true;

        case FKCONSTR_MATCH_FULL:
            /*
             * If all new key values are NULL, the row must satisfy the
             * constraint, so no check is needed.  On the other hand, if only
             * some of them are NULL, the row must fail the constraint.  We
             * must not throw error here, because the row might get
             * invalidated before the constraint is to be checked, but we
             * should queue the event to apply the check later.
             */
            switch (ri_NullCheck(new_row, riinfo, false))
            {
                case RI_KEYS_ALL_NULL:
                    return false;
                case RI_KEYS_SOME_NULL:
                    return true;
                case RI_KEYS_NONE_NULL:
                    break;      /* continue with the check */
            }

            /*
             * If the original row was inserted by our own transaction, we
             * must fire the trigger whether or not the keys are equal.  This
             * is because our UPDATE will invalidate the INSERT so that the
             * INSERT RI trigger will not do anything; so we had better do the
             * UPDATE check.  (We could skip this if we knew the INSERT
             * trigger already fired, but there is no easy way to know that.)
             */
            if (TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmin(old_row->t_data)))
                return true;

            /* If all old and new key values are equal, no check is needed */
            if (ri_KeysEqual(fk_rel, old_row, new_row, riinfo, false))
                return false;

            /* Else we need to fire the trigger. */
            return true;

            /* Handle MATCH PARTIAL check. */
        case FKCONSTR_MATCH_PARTIAL:
            ereport(ERROR,
                    (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                     errmsg("MATCH PARTIAL not yet implemented")));
            break;

        default:
            elog(ERROR, "unrecognized confmatchtype: %d",
                 riinfo->confmatchtype);
            break;
    }

    /* Never reached */
    return false;
}

/* ----------
 * RI_Initial_Check -
 *
 *  Check an entire table for non-matching values using a single query.
 *  This is not a trigger procedure, but is called during ALTER TABLE
 *  ADD FOREIGN KEY to validate the initial table contents.
 *
 *  We expect that the caller has made provision to prevent any problems
 *  caused by concurrent actions. This could be either by locking rel and
 *  pkrel at ShareRowExclusiveLock or higher, or by otherwise ensuring
 *  that triggers implementing the checks are already active.
 *  Hence, we do not need to lock individual rows for the check.
 *
 *  If the check fails because the current user doesn't have permissions
 *  to read both tables, return false to let our caller know that they will
 *  need to do something else to check the constraint.
 * ----------
 */
bool
RI_Initial_Check(Trigger *trigger, Relation fk_rel, Relation pk_rel)
{
    const RI_ConstraintInfo *riinfo;
    StringInfoData querybuf;
    char        pkrelname[MAX_QUOTED_REL_NAME_LEN];
    char        fkrelname[MAX_QUOTED_REL_NAME_LEN];
    char        pkattname[MAX_QUOTED_NAME_LEN + 3];
    char        fkattname[MAX_QUOTED_NAME_LEN + 3];
    RangeTblEntry *pkrte;
    RangeTblEntry *fkrte;
    const char *sep;
    int         i;
    int         save_nestlevel;
    char        workmembuf[32];
    int         spi_result;
    SPIPlanPtr  qplan;

    /* Fetch constraint info. */
    riinfo = ri_FetchConstraintInfo(trigger, fk_rel, false);

    /*
     * Check to make sure current user has enough permissions to do the test
     * query.  (If not, caller can fall back to the trigger method, which
     * works because it changes user IDs on the fly.)
     *
     * XXX are there any other show-stopper conditions to check?
     */
    pkrte = makeNode(RangeTblEntry);
    pkrte->rtekind = RTE_RELATION;
    pkrte->relid = RelationGetRelid(pk_rel);
    pkrte->relkind = pk_rel->rd_rel->relkind;
    pkrte->requiredPerms = ACL_SELECT;

    fkrte = makeNode(RangeTblEntry);
    fkrte->rtekind = RTE_RELATION;
    fkrte->relid = RelationGetRelid(fk_rel);
    fkrte->relkind = fk_rel->rd_rel->relkind;
    fkrte->requiredPerms = ACL_SELECT;

    for (i = 0; i < riinfo->nkeys; i++)
    {
        int         attno;

        attno = riinfo->pk_attnums[i] - FirstLowInvalidHeapAttributeNumber;
        pkrte->selectedCols = bms_add_member(pkrte->selectedCols, attno);

        attno = riinfo->fk_attnums[i] - FirstLowInvalidHeapAttributeNumber;
        fkrte->selectedCols = bms_add_member(fkrte->selectedCols, attno);
    }

    if (!ExecCheckRTPerms(list_make2(fkrte, pkrte), false))
        return false;

    /*----------
     * The query string built is:
     *  SELECT fk.keycols FROM ONLY relname fk
     *   LEFT OUTER JOIN ONLY pkrelname pk
     *   ON (pk.pkkeycol1=fk.keycol1 [AND ...])
     *   WHERE pk.pkkeycol1 IS NULL AND
     * For MATCH SIMPLE:
     *   (fk.keycol1 IS NOT NULL [AND ...])
     * For MATCH FULL:
     *   (fk.keycol1 IS NOT NULL [OR ...])
     *
     * We attach COLLATE clauses to the operators when comparing columns
     * that have different collations.
     *----------
     */
    initStringInfo(&querybuf);
    appendStringInfo(&querybuf, "SELECT ");
    sep = "";
    for (i = 0; i < riinfo->nkeys; i++)
    {
        quoteOneName(fkattname,
                     RIAttName(fk_rel, riinfo->fk_attnums[i]));
        appendStringInfo(&querybuf, "%sfk.%s", sep, fkattname);
        sep = ", ";
    }

    quoteRelationName(pkrelname, pk_rel);
    quoteRelationName(fkrelname, fk_rel);
    appendStringInfo(&querybuf,
                     " FROM ONLY %s fk LEFT OUTER JOIN ONLY %s pk ON",
                     fkrelname, pkrelname);

    strcpy(pkattname, "pk.");
    strcpy(fkattname, "fk.");
    sep = "(";
    for (i = 0; i < riinfo->nkeys; i++)
    {
        Oid         pk_type = RIAttType(pk_rel, riinfo->pk_attnums[i]);
        Oid         fk_type = RIAttType(fk_rel, riinfo->fk_attnums[i]);
        Oid         pk_coll = RIAttCollation(pk_rel, riinfo->pk_attnums[i]);
        Oid         fk_coll = RIAttCollation(fk_rel, riinfo->fk_attnums[i]);

        quoteOneName(pkattname + 3,
                     RIAttName(pk_rel, riinfo->pk_attnums[i]));
        quoteOneName(fkattname + 3,
                     RIAttName(fk_rel, riinfo->fk_attnums[i]));
        ri_GenerateQual(&querybuf, sep,
                        pkattname, pk_type,
                        riinfo->pf_eq_oprs[i],
                        fkattname, fk_type);
        if (pk_coll != fk_coll)
            ri_GenerateQualCollation(&querybuf, pk_coll);
        sep = "AND";
    }

    /*
     * It's sufficient to test any one pk attribute for null to detect a join
     * failure.
     */
    quoteOneName(pkattname, RIAttName(pk_rel, riinfo->pk_attnums[0]));
    appendStringInfo(&querybuf, ") WHERE pk.%s IS NULL AND (", pkattname);

    sep = "";
    for (i = 0; i < riinfo->nkeys; i++)
    {
        quoteOneName(fkattname, RIAttName(fk_rel, riinfo->fk_attnums[i]));
        appendStringInfo(&querybuf,
                         "%sfk.%s IS NOT NULL",
                         sep, fkattname);
        switch (riinfo->confmatchtype)
        {
            case FKCONSTR_MATCH_SIMPLE:
                sep = " AND ";
                break;
            case FKCONSTR_MATCH_FULL:
                sep = " OR ";
                break;
            case FKCONSTR_MATCH_PARTIAL:
                ereport(ERROR,
                        (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                         errmsg("MATCH PARTIAL not yet implemented")));
                break;
            default:
                elog(ERROR, "unrecognized confmatchtype: %d",
                     riinfo->confmatchtype);
                break;
        }
    }
    appendStringInfo(&querybuf, ")");

    /*
     * Temporarily increase work_mem so that the check query can be executed
     * more efficiently.  It seems okay to do this because the query is simple
     * enough to not use a multiple of work_mem, and one typically would not
     * have many large foreign-key validations happening concurrently.  So
     * this seems to meet the criteria for being considered a "maintenance"
     * operation, and accordingly we use maintenance_work_mem.
     *
     * We use the equivalent of a function SET option to allow the setting to
     * persist for exactly the duration of the check query.  guc.c also takes
     * care of undoing the setting on error.
     */
    save_nestlevel = NewGUCNestLevel();

    snprintf(workmembuf, sizeof(workmembuf), "%d", maintenance_work_mem);
    (void) set_config_option("work_mem", workmembuf,
                             PGC_USERSET, PGC_S_SESSION,
                             GUC_ACTION_SAVE, true, 0);

    if (SPI_connect() != SPI_OK_CONNECT)
        elog(ERROR, "SPI_connect failed");

    /*
     * Generate the plan.  We don't need to cache it, and there are no
     * arguments to the plan.
     */
    qplan = SPI_prepare(querybuf.data, 0, NULL);

    if (qplan == NULL)
        elog(ERROR, "SPI_prepare returned %d for %s",
             SPI_result, querybuf.data);

    /*
     * Run the plan.  For safety we force a current snapshot to be used. (In
     * transaction-snapshot mode, this arguably violates transaction isolation
     * rules, but we really haven't got much choice.) We don't need to
     * register the snapshot, because SPI_execute_snapshot will see to it. We
     * need at most one tuple returned, so pass limit = 1.
     */
    spi_result = SPI_execute_snapshot(qplan,
                                      NULL, NULL,
                                      GetLatestSnapshot(),
                                      InvalidSnapshot,
                                      true, false, 1);

    /* Check result */
    if (spi_result != SPI_OK_SELECT)
        elog(ERROR, "SPI_execute_snapshot returned %d", spi_result);

    /* Did we find a tuple violating the constraint? */
    if (SPI_processed > 0)
    {
        HeapTuple   tuple = SPI_tuptable->vals[0];
        TupleDesc   tupdesc = SPI_tuptable->tupdesc;
        RI_ConstraintInfo fake_riinfo;

        /*
         * The columns to look at in the result tuple are 1..N, not whatever
         * they are in the fk_rel.  Hack up riinfo so that the subroutines
         * called here will behave properly.
         *
         * In addition to this, we have to pass the correct tupdesc to
         * ri_ReportViolation, overriding its normal habit of using the pk_rel
         * or fk_rel's tupdesc.
         */
        memcpy(&fake_riinfo, riinfo, sizeof(RI_ConstraintInfo));
        for (i = 0; i < fake_riinfo.nkeys; i++)
            fake_riinfo.fk_attnums[i] = i + 1;

        /*
         * If it's MATCH FULL, and there are any nulls in the FK keys,
         * complain about that rather than the lack of a match.  MATCH FULL
         * disallows partially-null FK rows.
         */
        if (fake_riinfo.confmatchtype == FKCONSTR_MATCH_FULL &&
            ri_NullCheck(tuple, &fake_riinfo, false) != RI_KEYS_NONE_NULL)
            ereport(ERROR,
                    (errcode(ERRCODE_FOREIGN_KEY_VIOLATION),
                     errmsg("insert or update on table \"%s\" violates foreign key constraint \"%s\"",
                            RelationGetRelationName(fk_rel),
                            NameStr(fake_riinfo.conname)),
                     errdetail("MATCH FULL does not allow mixing of null and nonnull key values."),
                     errtableconstraint(fk_rel,
                                        NameStr(fake_riinfo.conname))));

        /*
         * We tell ri_ReportViolation we were doing the RI_PLAN_CHECK_LOOKUPPK
         * query, which isn't true, but will cause it to use
         * fake_riinfo.fk_attnums as we need.
         */
        ri_ReportViolation(&fake_riinfo,
                           pk_rel, fk_rel,
                           tuple, tupdesc,
                           RI_PLAN_CHECK_LOOKUPPK, false);
    }

    if (SPI_finish() != SPI_OK_FINISH)
        elog(ERROR, "SPI_finish failed");

    /*
     * Restore work_mem.
     */
    AtEOXact_GUC(true, save_nestlevel);

    return true;
}


/* ----------
 * Local functions below
 * ----------
 */


/*
 * quoteOneName --- safely quote a single SQL name
 *
 * buffer must be MAX_QUOTED_NAME_LEN long (includes room for \0)
 */
static void
quoteOneName(char *buffer, const char *name)
{
    /* Rather than trying to be smart, just always quote it. */
    *buffer++ = '"';
    while (*name)
    {
        if (*name == '"')
            *buffer++ = '"';
        *buffer++ = *name++;
    }
    *buffer++ = '"';
    *buffer = '\0';
}

/*
 * quoteRelationName --- safely quote a fully qualified relation name
 *
 * buffer must be MAX_QUOTED_REL_NAME_LEN long (includes room for \0)
 */
static void
quoteRelationName(char *buffer, Relation rel)
{
    quoteOneName(buffer, get_namespace_name(RelationGetNamespace(rel)));
    buffer += strlen(buffer);
    *buffer++ = '.';
    quoteOneName(buffer, RelationGetRelationName(rel));
}

/*
 * ri_GenerateQual --- generate a WHERE clause equating two variables
 *
 * The idea is to append " sep leftop op rightop" to buf.  The complexity
 * comes from needing to be sure that the parser will select the desired
 * operator.  We always name the operator using OPERATOR(schema.op) syntax
 * (readability isn't a big priority here), so as to avoid search-path
 * uncertainties.  We have to emit casts too, if either input isn't already
 * the input type of the operator; else we are at the mercy of the parser's
 * heuristics for ambiguous-operator resolution.
 */
static void
ri_GenerateQual(StringInfo buf,
                const char *sep,
                const char *leftop, Oid leftoptype,
                Oid opoid,
                const char *rightop, Oid rightoptype)
{
    HeapTuple   opertup;
    Form_pg_operator operform;
    char       *oprname;
    char       *nspname;

    opertup = SearchSysCache1(OPEROID, ObjectIdGetDatum(opoid));
    if (!HeapTupleIsValid(opertup))
        elog(ERROR, "cache lookup failed for operator %u", opoid);
    operform = (Form_pg_operator) GETSTRUCT(opertup);
    Assert(operform->oprkind == 'b');
    oprname = NameStr(operform->oprname);

    nspname = get_namespace_name(operform->oprnamespace);

    appendStringInfo(buf, " %s %s", sep, leftop);
    if (leftoptype != operform->oprleft)
        ri_add_cast_to(buf, operform->oprleft);
    appendStringInfo(buf, " OPERATOR(%s.", quote_identifier(nspname));
    appendStringInfoString(buf, oprname);
    appendStringInfo(buf, ") %s", rightop);
    if (rightoptype != operform->oprright)
        ri_add_cast_to(buf, operform->oprright);

    ReleaseSysCache(opertup);
}

/*
 * Add a cast specification to buf.  We spell out the type name the hard way,
 * intentionally not using format_type_be().  This is to avoid corner cases
 * for CHARACTER, BIT, and perhaps other types, where specifying the type
 * using SQL-standard syntax results in undesirable data truncation.  By
 * doing it this way we can be certain that the cast will have default (-1)
 * target typmod.
 */
static void
ri_add_cast_to(StringInfo buf, Oid typid)
{
    HeapTuple   typetup;
    Form_pg_type typform;
    char       *typname;
    char       *nspname;

    typetup = SearchSysCache1(TYPEOID, ObjectIdGetDatum(typid));
    if (!HeapTupleIsValid(typetup))
        elog(ERROR, "cache lookup failed for type %u", typid);
    typform = (Form_pg_type) GETSTRUCT(typetup);

    typname = NameStr(typform->typname);
    nspname = get_namespace_name(typform->typnamespace);

    appendStringInfo(buf, "::%s.%s",
                     quote_identifier(nspname), quote_identifier(typname));

    ReleaseSysCache(typetup);
}

/*
 * ri_GenerateQualCollation --- add a COLLATE spec to a WHERE clause
 *
 * At present, we intentionally do not use this function for RI queries that
 * compare a variable to a $n parameter.  Since parameter symbols always have
 * default collation, the effect will be to use the variable's collation.
 * Now that is only strictly correct when testing the referenced column, since
 * the SQL standard specifies that RI comparisons should use the referenced
 * column's collation.  However, so long as all collations have the same
 * notion of equality (which they do, because texteq reduces to bitwise
 * equality), there's no visible semantic impact from using the referencing
 * column's collation when testing it, and this is a good thing to do because
 * it lets us use a normal index on the referencing column.  However, we do
 * have to use this function when directly comparing the referencing and
 * referenced columns, if they are of different collations; else the parser
 * will fail to resolve the collation to use.
 */
static void
ri_GenerateQualCollation(StringInfo buf, Oid collation)
{
    HeapTuple   tp;
    Form_pg_collation colltup;
    char       *collname;
    char        onename[MAX_QUOTED_NAME_LEN];

    /* Nothing to do if it's a noncollatable data type */
    if (!OidIsValid(collation))
        return;

    tp = SearchSysCache1(COLLOID, ObjectIdGetDatum(collation));
    if (!HeapTupleIsValid(tp))
        elog(ERROR, "cache lookup failed for collation %u", collation);
    colltup = (Form_pg_collation) GETSTRUCT(tp);
    collname = NameStr(colltup->collname);

    /*
     * We qualify the name always, for simplicity and to ensure the query is
     * not search-path-dependent.
     */
    quoteOneName(onename, get_namespace_name(colltup->collnamespace));
    appendStringInfo(buf, " COLLATE %s", onename);
    quoteOneName(onename, collname);
    appendStringInfo(buf, ".%s", onename);

    ReleaseSysCache(tp);
}

/* ----------
 * ri_BuildQueryKey -
 *
 *  Construct a hashtable key for a prepared SPI plan of an FK constraint.
 *
 *      key: output argument, *key is filled in based on the other arguments
 *      riinfo: info from pg_constraint entry
 *      constr_queryno: an internal number identifying the query type
 *          (see RI_PLAN_XXX constants at head of file)
 * ----------
 */
static void
ri_BuildQueryKey(RI_QueryKey *key, const RI_ConstraintInfo *riinfo,
                 int32 constr_queryno)
{
    /*
     * We assume struct RI_QueryKey contains no padding bytes, else we'd
     * need to use memset to clear them.
     */
    key->constr_id = riinfo->constraint_id;
    key->constr_queryno = constr_queryno;
}

/*
 * Check that RI trigger function was called in expected context
 */
static void
ri_CheckTrigger(FunctionCallInfo fcinfo, const char *funcname, int tgkind)
{
    TriggerData *trigdata = (TriggerData *) fcinfo->context;

    if (!CALLED_AS_TRIGGER(fcinfo))
        ereport(ERROR,
                (errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
                 errmsg("function \"%s\" was not called by trigger manager", funcname)));

    /*
     * Check proper event
     */
    if (!TRIGGER_FIRED_AFTER(trigdata->tg_event) ||
        !TRIGGER_FIRED_FOR_ROW(trigdata->tg_event))
        ereport(ERROR,
                (errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
               errmsg("function \"%s\" must be fired AFTER ROW", funcname)));

    switch (tgkind)
    {
        case RI_TRIGTYPE_INSERT:
            if (!TRIGGER_FIRED_BY_INSERT(trigdata->tg_event))
                ereport(ERROR,
                        (errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
                         errmsg("function \"%s\" must be fired for INSERT", funcname)));
            break;
        case RI_TRIGTYPE_UPDATE:
            if (!TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
                ereport(ERROR,
                        (errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
                         errmsg("function \"%s\" must be fired for UPDATE", funcname)));
            break;
        case RI_TRIGTYPE_DELETE:
            if (!TRIGGER_FIRED_BY_DELETE(trigdata->tg_event))
                ereport(ERROR,
                        (errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
                         errmsg("function \"%s\" must be fired for DELETE", funcname)));
            break;
    }
}


/*
 * Fetch the RI_ConstraintInfo struct for the trigger's FK constraint.
 */
static const RI_ConstraintInfo *
ri_FetchConstraintInfo(Trigger *trigger, Relation trig_rel, bool rel_is_pk)
{
    Oid         constraintOid = trigger->tgconstraint;
    const RI_ConstraintInfo *riinfo;

    /*
     * Check that the FK constraint's OID is available; it might not be if
     * we've been invoked via an ordinary trigger or an old-style "constraint
     * trigger".
     */
    if (!OidIsValid(constraintOid))
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
          errmsg("no pg_constraint entry for trigger \"%s\" on table \"%s\"",
                 trigger->tgname, RelationGetRelationName(trig_rel)),
                 errhint("Remove this referential integrity trigger and its mates, then do ALTER TABLE ADD CONSTRAINT.")));

    /* Find or create a hashtable entry for the constraint */
    riinfo = ri_LoadConstraintInfo(constraintOid);

    /* Do some easy cross-checks against the trigger call data */
    if (rel_is_pk)
    {
        if (riinfo->fk_relid != trigger->tgconstrrelid ||
            riinfo->pk_relid != RelationGetRelid(trig_rel))
            elog(ERROR, "wrong pg_constraint entry for trigger \"%s\" on table \"%s\"",
                 trigger->tgname, RelationGetRelationName(trig_rel));
    }
    else
    {
        if (riinfo->fk_relid != RelationGetRelid(trig_rel) ||
            riinfo->pk_relid != trigger->tgconstrrelid)
            elog(ERROR, "wrong pg_constraint entry for trigger \"%s\" on table \"%s\"",
                 trigger->tgname, RelationGetRelationName(trig_rel));
    }

    return riinfo;
}

/*
 * Fetch or create the RI_ConstraintInfo struct for an FK constraint.
 */
static const RI_ConstraintInfo *
ri_LoadConstraintInfo(Oid constraintOid)
{
    RI_ConstraintInfo *riinfo;
    bool        found;
    HeapTuple   tup;
    Form_pg_constraint conForm;
    Datum       adatum;
    bool        isNull;
    ArrayType  *arr;
    int         numkeys;

    /*
     * On the first call initialize the hashtable
     */
    if (!ri_constraint_cache)
        ri_InitHashTables();

    /*
     * Find or create a hash entry.  If we find a valid one, just return it.
     */
    riinfo = (RI_ConstraintInfo *) hash_search(ri_constraint_cache,
                                               (void *) &constraintOid,
                                               HASH_ENTER, &found);
    if (!found)
        riinfo->valid = false;
    else if (riinfo->valid)
        return riinfo;

    /*
     * Fetch the pg_constraint row so we can fill in the entry.
     */
    tup = SearchSysCache1(CONSTROID, ObjectIdGetDatum(constraintOid));
    if (!HeapTupleIsValid(tup)) /* should not happen */
        elog(ERROR, "cache lookup failed for constraint %u", constraintOid);
    conForm = (Form_pg_constraint) GETSTRUCT(tup);

    if (conForm->contype != CONSTRAINT_FOREIGN) /* should not happen */
        elog(ERROR, "constraint %u is not a foreign key constraint",
             constraintOid);

    /* And extract data */
    Assert(riinfo->constraint_id == constraintOid);
    riinfo->oidHashValue = GetSysCacheHashValue1(CONSTROID,
                                             ObjectIdGetDatum(constraintOid));
    memcpy(&riinfo->conname, &conForm->conname, sizeof(NameData));
    riinfo->pk_relid = conForm->confrelid;
    riinfo->fk_relid = conForm->conrelid;
    riinfo->confupdtype = conForm->confupdtype;
    riinfo->confdeltype = conForm->confdeltype;
    riinfo->confmatchtype = conForm->confmatchtype;

    /*
     * We expect the arrays to be 1-D arrays of the right types; verify that.
     * We don't need to use deconstruct_array() since the array data is just
     * going to look like a C array of values.
     */
    adatum = SysCacheGetAttr(CONSTROID, tup,
                             Anum_pg_constraint_conkey, &isNull);
    if (isNull)
        elog(ERROR, "null conkey for constraint %u", constraintOid);
    arr = DatumGetArrayTypeP(adatum);   /* ensure not toasted */
    if (ARR_NDIM(arr) != 1 ||
        ARR_HASNULL(arr) ||
        ARR_ELEMTYPE(arr) != INT2OID)
        elog(ERROR, "conkey is not a 1-D smallint array");
    numkeys = ARR_DIMS(arr)[0];
    if (numkeys <= 0 || numkeys > RI_MAX_NUMKEYS)
        elog(ERROR, "foreign key constraint cannot have %d columns", numkeys);
    riinfo->nkeys = numkeys;
    memcpy(riinfo->fk_attnums, ARR_DATA_PTR(arr), numkeys * sizeof(int16));
    if ((Pointer) arr != DatumGetPointer(adatum))
        pfree(arr);             /* free de-toasted copy, if any */

    adatum = SysCacheGetAttr(CONSTROID, tup,
                             Anum_pg_constraint_confkey, &isNull);
    if (isNull)
        elog(ERROR, "null confkey for constraint %u", constraintOid);
    arr = DatumGetArrayTypeP(adatum);   /* ensure not toasted */
    if (ARR_NDIM(arr) != 1 ||
        ARR_DIMS(arr)[0] != numkeys ||
        ARR_HASNULL(arr) ||
        ARR_ELEMTYPE(arr) != INT2OID)
        elog(ERROR, "confkey is not a 1-D smallint array");
    memcpy(riinfo->pk_attnums, ARR_DATA_PTR(arr), numkeys * sizeof(int16));
    if ((Pointer) arr != DatumGetPointer(adatum))
        pfree(arr);             /* free de-toasted copy, if any */

    adatum = SysCacheGetAttr(CONSTROID, tup,
                             Anum_pg_constraint_conpfeqop, &isNull);
    if (isNull)
        elog(ERROR, "null conpfeqop for constraint %u", constraintOid);
    arr = DatumGetArrayTypeP(adatum);   /* ensure not toasted */
    /* see TryReuseForeignKey if you change the test below */
    if (ARR_NDIM(arr) != 1 ||
        ARR_DIMS(arr)[0] != numkeys ||
        ARR_HASNULL(arr) ||
        ARR_ELEMTYPE(arr) != OIDOID)
        elog(ERROR, "conpfeqop is not a 1-D Oid array");
    memcpy(riinfo->pf_eq_oprs, ARR_DATA_PTR(arr), numkeys * sizeof(Oid));
    if ((Pointer) arr != DatumGetPointer(adatum))
        pfree(arr);             /* free de-toasted copy, if any */

    adatum = SysCacheGetAttr(CONSTROID, tup,
                             Anum_pg_constraint_conppeqop, &isNull);
    if (isNull)
        elog(ERROR, "null conppeqop for constraint %u", constraintOid);
    arr = DatumGetArrayTypeP(adatum);   /* ensure not toasted */
    if (ARR_NDIM(arr) != 1 ||
        ARR_DIMS(arr)[0] != numkeys ||
        ARR_HASNULL(arr) ||
        ARR_ELEMTYPE(arr) != OIDOID)
        elog(ERROR, "conppeqop is not a 1-D Oid array");
    memcpy(riinfo->pp_eq_oprs, ARR_DATA_PTR(arr), numkeys * sizeof(Oid));
    if ((Pointer) arr != DatumGetPointer(adatum))
        pfree(arr);             /* free de-toasted copy, if any */

    adatum = SysCacheGetAttr(CONSTROID, tup,
                             Anum_pg_constraint_conffeqop, &isNull);
    if (isNull)
        elog(ERROR, "null conffeqop for constraint %u", constraintOid);
    arr = DatumGetArrayTypeP(adatum);   /* ensure not toasted */
    if (ARR_NDIM(arr) != 1 ||
        ARR_DIMS(arr)[0] != numkeys ||
        ARR_HASNULL(arr) ||
        ARR_ELEMTYPE(arr) != OIDOID)
        elog(ERROR, "conffeqop is not a 1-D Oid array");
    memcpy(riinfo->ff_eq_oprs, ARR_DATA_PTR(arr), numkeys * sizeof(Oid));
    if ((Pointer) arr != DatumGetPointer(adatum))
        pfree(arr);             /* free de-toasted copy, if any */

    ReleaseSysCache(tup);

    riinfo->valid = true;

    return riinfo;
}

/*
 * Callback for pg_constraint inval events
 *
 * While most syscache callbacks just flush all their entries, pg_constraint
 * gets enough update traffic that it's probably worth being smarter.
 * Invalidate any ri_constraint_cache entry associated with the syscache
 * entry with the specified hash value, or all entries if hashvalue == 0.
 */
static void
InvalidateConstraintCacheCallBack(Datum arg, int cacheid, uint32 hashvalue)
{
    HASH_SEQ_STATUS status;
    RI_ConstraintInfo *hentry;

    Assert(ri_constraint_cache != NULL);

    hash_seq_init(&status, ri_constraint_cache);
    while ((hentry = (RI_ConstraintInfo *) hash_seq_search(&status)) != NULL)
    {
        if (hashvalue == 0 || hentry->oidHashValue == hashvalue)
            hentry->valid = false;
    }
}


/*
 * Prepare execution plan for a query to enforce an RI restriction
 *
 * If cache_plan is true, the plan is saved into our plan hashtable
 * so that we don't need to plan it again.
 */
static SPIPlanPtr
ri_PlanCheck(const char *querystr, int nargs, Oid *argtypes,
             RI_QueryKey *qkey, Relation fk_rel, Relation pk_rel,
             bool cache_plan)
{
    SPIPlanPtr  qplan;
    Relation    query_rel;
    Oid         save_userid;
    int         save_sec_context;

    /*
     * Use the query type code to determine whether the query is run against
     * the PK or FK table; we'll do the check as that table's owner
     */
    if (qkey->constr_queryno <= RI_PLAN_LAST_ON_PK)
        query_rel = pk_rel;
    else
        query_rel = fk_rel;

    /* Switch to proper UID to perform check as */
    GetUserIdAndSecContext(&save_userid, &save_sec_context);
    SetUserIdAndSecContext(RelationGetForm(query_rel)->relowner,
                           save_sec_context | SECURITY_LOCAL_USERID_CHANGE);

    /* Create the plan */
    qplan = SPI_prepare(querystr, nargs, argtypes);

    if (qplan == NULL)
        elog(ERROR, "SPI_prepare returned %d for %s", SPI_result, querystr);

    /* Restore UID and security context */
    SetUserIdAndSecContext(save_userid, save_sec_context);

    /* Save the plan if requested */
    if (cache_plan)
    {
        SPI_keepplan(qplan);
        ri_HashPreparedPlan(qkey, qplan);
    }

    return qplan;
}

/*
 * Perform a query to enforce an RI restriction
 */
static bool
ri_PerformCheck(const RI_ConstraintInfo *riinfo,
                RI_QueryKey *qkey, SPIPlanPtr qplan,
                Relation fk_rel, Relation pk_rel,
                HeapTuple old_tuple, HeapTuple new_tuple,
                bool detectNewRows, int expect_OK)
{
    Relation    query_rel,
                source_rel;
    bool        source_is_pk;
    Snapshot    test_snapshot;
    Snapshot    crosscheck_snapshot;
    int         limit;
    int         spi_result;
    Oid         save_userid;
    int         save_sec_context;
    Datum       vals[RI_MAX_NUMKEYS * 2];
    char        nulls[RI_MAX_NUMKEYS * 2];

    /*
     * Use the query type code to determine whether the query is run against
     * the PK or FK table; we'll do the check as that table's owner
     */
    if (qkey->constr_queryno <= RI_PLAN_LAST_ON_PK)
        query_rel = pk_rel;
    else
        query_rel = fk_rel;

    /*
     * The values for the query are taken from the table on which the trigger
     * is called - it is normally the other one with respect to query_rel.
     * An exception is ri_Check_Pk_Match(), which uses the PK table for both
     * (and sets queryno to RI_PLAN_CHECK_LOOKUPPK_FROM_PK).  We might
     * eventually need some less klugy way to determine this.
     */
    if (qkey->constr_queryno == RI_PLAN_CHECK_LOOKUPPK)
    {
        source_rel = fk_rel;
        source_is_pk = false;
    }
    else
    {
        source_rel = pk_rel;
        source_is_pk = true;
    }

    /* Extract the parameters to be passed into the query */
    if (new_tuple)
    {
        ri_ExtractValues(source_rel, new_tuple, riinfo, source_is_pk,
                         vals, nulls);
        if (old_tuple)
            ri_ExtractValues(source_rel, old_tuple, riinfo, source_is_pk,
                             vals + riinfo->nkeys, nulls + riinfo->nkeys);
    }
    else
    {
        ri_ExtractValues(source_rel, old_tuple, riinfo, source_is_pk,
                         vals, nulls);
    }

    /*
     * In READ COMMITTED mode, we just need to use an up-to-date regular
     * snapshot, and we will see all rows that could be interesting. But in
     * transaction-snapshot mode, we can't change the transaction snapshot. If
     * the caller passes detectNewRows == false then it's okay to do the query
     * with the transaction snapshot; otherwise we use a current snapshot, and
     * tell the executor to error out if it finds any rows under the current
     * snapshot that wouldn't be visible per the transaction snapshot.  Note
     * that SPI_execute_snapshot will register the snapshots, so we don't need
     * to bother here.
     */
    if (IsolationUsesXactSnapshot() && detectNewRows)
    {
        CommandCounterIncrement();      /* be sure all my own work is visible */
        test_snapshot = GetLatestSnapshot();
        crosscheck_snapshot = GetTransactionSnapshot();
    }
    else
    {
        /* the default SPI behavior is okay */
        test_snapshot = InvalidSnapshot;
        crosscheck_snapshot = InvalidSnapshot;
    }

    /*
     * If this is a select query (e.g., for a 'no action' or 'restrict'
     * trigger), we only need to see if there is a single row in the table,
     * matching the key.  Otherwise, limit = 0 - because we want the query to
     * affect ALL the matching rows.
     */
    limit = (expect_OK == SPI_OK_SELECT) ? 1 : 0;

    /* Switch to proper UID to perform check as */
    GetUserIdAndSecContext(&save_userid, &save_sec_context);
    SetUserIdAndSecContext(RelationGetForm(query_rel)->relowner,
                           save_sec_context | SECURITY_LOCAL_USERID_CHANGE);

    /* Finally we can run the query. */
    spi_result = SPI_execute_snapshot(qplan,
                                      vals, nulls,
                                      test_snapshot, crosscheck_snapshot,
                                      false, false, limit);

    /* Restore UID and security context */
    SetUserIdAndSecContext(save_userid, save_sec_context);

    /* Check result */
    if (spi_result < 0)
        elog(ERROR, "SPI_execute_snapshot returned %d", spi_result);

    if (expect_OK >= 0 && spi_result != expect_OK)
        ri_ReportViolation(riinfo,
                           pk_rel, fk_rel,
                           new_tuple ? new_tuple : old_tuple,
                           NULL,
                           qkey->constr_queryno, true);

    /* XXX wouldn't it be clearer to do this part at the caller? */
    if (qkey->constr_queryno != RI_PLAN_CHECK_LOOKUPPK_FROM_PK &&
        expect_OK == SPI_OK_SELECT &&
    (SPI_processed == 0) == (qkey->constr_queryno == RI_PLAN_CHECK_LOOKUPPK))
        ri_ReportViolation(riinfo,
                           pk_rel, fk_rel,
                           new_tuple ? new_tuple : old_tuple,
                           NULL,
                           qkey->constr_queryno, false);

    return SPI_processed != 0;
}

/*
 * Extract fields from a tuple into Datum/nulls arrays
 */
static void
ri_ExtractValues(Relation rel, HeapTuple tup,
                 const RI_ConstraintInfo *riinfo, bool rel_is_pk,
                 Datum *vals, char *nulls)
{
    TupleDesc   tupdesc = rel->rd_att;
    const int16 *attnums;
    int         i;
    bool        isnull;

    if (rel_is_pk)
        attnums = riinfo->pk_attnums;
    else
        attnums = riinfo->fk_attnums;

    for (i = 0; i < riinfo->nkeys; i++)
    {
        vals[i] = heap_getattr(tup, attnums[i], tupdesc,
                               &isnull);
        nulls[i] = isnull ? 'n' : ' ';
    }
}

/*
 * Produce an error report
 *
 * If the failed constraint was on insert/update to the FK table,
 * we want the key names and values extracted from there, and the error
 * message to look like 'key blah is not present in PK'.
 * Otherwise, the attr names and values come from the PK table and the
 * message looks like 'key blah is still referenced from FK'.
 */
static void
ri_ReportViolation(const RI_ConstraintInfo *riinfo,
                   Relation pk_rel, Relation fk_rel,
                   HeapTuple violator, TupleDesc tupdesc,
                   int queryno, bool spi_err)
{
    StringInfoData key_names;
    StringInfoData key_values;
    bool        onfk;
    const int16 *attnums;
    int         idx;

    if (spi_err)
        ereport(ERROR,
                (errcode(ERRCODE_INTERNAL_ERROR),
                 errmsg("referential integrity query on \"%s\" from constraint \"%s\" on \"%s\" gave unexpected result",
                        RelationGetRelationName(pk_rel),
                        NameStr(riinfo->conname),
                        RelationGetRelationName(fk_rel)),
                 errhint("This is most likely due to a rule having rewritten the query.")));

    /*
     * Determine which relation to complain about.  If tupdesc wasn't passed
     * by caller, assume the violator tuple came from there.
     */
    onfk = (queryno == RI_PLAN_CHECK_LOOKUPPK);
    if (onfk)
    {
        attnums = riinfo->fk_attnums;
        if (tupdesc == NULL)
            tupdesc = fk_rel->rd_att;
    }
    else
    {
        attnums = riinfo->pk_attnums;
        if (tupdesc == NULL)
            tupdesc = pk_rel->rd_att;
    }

    /* Get printable versions of the keys involved */
    initStringInfo(&key_names);
    initStringInfo(&key_values);
    for (idx = 0; idx < riinfo->nkeys; idx++)
    {
        int         fnum = attnums[idx];
        char       *name,
                   *val;

        name = SPI_fname(tupdesc, fnum);
        val = SPI_getvalue(violator, tupdesc, fnum);
        if (!val)
            val = "null";

        if (idx > 0)
        {
            appendStringInfoString(&key_names, ", ");
            appendStringInfoString(&key_values, ", ");
        }
        appendStringInfoString(&key_names, name);
        appendStringInfoString(&key_values, val);
    }

    if (onfk)
        ereport(ERROR,
                (errcode(ERRCODE_FOREIGN_KEY_VIOLATION),
                 errmsg("insert or update on table \"%s\" violates foreign key constraint \"%s\"",
                        RelationGetRelationName(fk_rel),
                        NameStr(riinfo->conname)),
                 errdetail("Key (%s)=(%s) is not present in table \"%s\".",
                           key_names.data, key_values.data,
                           RelationGetRelationName(pk_rel)),
                 errtableconstraint(fk_rel, NameStr(riinfo->conname))));
    else
        ereport(ERROR,
                (errcode(ERRCODE_FOREIGN_KEY_VIOLATION),
                 errmsg("update or delete on table \"%s\" violates foreign key constraint \"%s\" on table \"%s\"",
                        RelationGetRelationName(pk_rel),
                        NameStr(riinfo->conname),
                        RelationGetRelationName(fk_rel)),
            errdetail("Key (%s)=(%s) is still referenced from table \"%s\".",
                      key_names.data, key_values.data,
                      RelationGetRelationName(fk_rel)),
                 errtableconstraint(fk_rel, NameStr(riinfo->conname))));
}


/* ----------
 * ri_NullCheck -
 *
 *  Determine the NULL state of all key values in a tuple
 *
 *  Returns one of RI_KEYS_ALL_NULL, RI_KEYS_NONE_NULL or RI_KEYS_SOME_NULL.
 * ----------
 */
static int
ri_NullCheck(HeapTuple tup,
             const RI_ConstraintInfo *riinfo, bool rel_is_pk)
{
    const int16 *attnums;
    int         i;
    bool        allnull = true;
    bool        nonenull = true;

    if (rel_is_pk)
        attnums = riinfo->pk_attnums;
    else
        attnums = riinfo->fk_attnums;

    for (i = 0; i < riinfo->nkeys; i++)
    {
        if (heap_attisnull(tup, attnums[i]))
            nonenull = false;
        else
            allnull = false;
    }

    if (allnull)
        return RI_KEYS_ALL_NULL;

    if (nonenull)
        return RI_KEYS_NONE_NULL;

    return RI_KEYS_SOME_NULL;
}


/* ----------
 * ri_InitHashTables -
 *
 *  Initialize our internal hash tables.
 * ----------
 */
static void
ri_InitHashTables(void)
{
    HASHCTL     ctl;

    memset(&ctl, 0, sizeof(ctl));
    ctl.keysize = sizeof(Oid);
    ctl.entrysize = sizeof(RI_ConstraintInfo);
    ctl.hash = oid_hash;
    ri_constraint_cache = hash_create("RI constraint cache",
                                      RI_INIT_CONSTRAINTHASHSIZE,
                                      &ctl, HASH_ELEM | HASH_FUNCTION);

    /* Arrange to flush cache on pg_constraint changes */
    CacheRegisterSyscacheCallback(CONSTROID,
                                  InvalidateConstraintCacheCallBack,
                                  (Datum) 0);

    memset(&ctl, 0, sizeof(ctl));
    ctl.keysize = sizeof(RI_QueryKey);
    ctl.entrysize = sizeof(RI_QueryHashEntry);
    ctl.hash = tag_hash;
    ri_query_cache = hash_create("RI query cache",
                                 RI_INIT_QUERYHASHSIZE,
                                 &ctl, HASH_ELEM | HASH_FUNCTION);

    memset(&ctl, 0, sizeof(ctl));
    ctl.keysize = sizeof(RI_CompareKey);
    ctl.entrysize = sizeof(RI_CompareHashEntry);
    ctl.hash = tag_hash;
    ri_compare_cache = hash_create("RI compare cache",
                                   RI_INIT_QUERYHASHSIZE,
                                   &ctl, HASH_ELEM | HASH_FUNCTION);
}


/* ----------
 * ri_FetchPreparedPlan -
 *
 *  Lookup for a query key in our private hash table of prepared
 *  and saved SPI execution plans. Return the plan if found or NULL.
 * ----------
 */
static SPIPlanPtr
ri_FetchPreparedPlan(RI_QueryKey *key)
{
    RI_QueryHashEntry *entry;
    SPIPlanPtr  plan;

    /*
     * On the first call initialize the hashtable
     */
    if (!ri_query_cache)
        ri_InitHashTables();

    /*
     * Lookup for the key
     */
    entry = (RI_QueryHashEntry *) hash_search(ri_query_cache,
                                              (void *) key,
                                              HASH_FIND, NULL);
    if (entry == NULL)
        return NULL;

    /*
     * Check whether the plan is still valid.  If it isn't, we don't want to
     * simply rely on plancache.c to regenerate it; rather we should start
     * from scratch and rebuild the query text too.  This is to cover cases
     * such as table/column renames.  We depend on the plancache machinery to
     * detect possible invalidations, though.
     *
     * CAUTION: this check is only trustworthy if the caller has already
     * locked both FK and PK rels.
     */
    plan = entry->plan;
    if (plan && SPI_plan_is_valid(plan))
        return plan;

    /*
     * Otherwise we might as well flush the cached plan now, to free a little
     * memory space before we make a new one.
     */
    entry->plan = NULL;
    if (plan)
        SPI_freeplan(plan);

    return NULL;
}


/* ----------
 * ri_HashPreparedPlan -
 *
 *  Add another plan to our private SPI query plan hashtable.
 * ----------
 */
static void
ri_HashPreparedPlan(RI_QueryKey *key, SPIPlanPtr plan)
{
    RI_QueryHashEntry *entry;
    bool        found;

    /*
     * On the first call initialize the hashtable
     */
    if (!ri_query_cache)
        ri_InitHashTables();

    /*
     * Add the new plan.  We might be overwriting an entry previously found
     * invalid by ri_FetchPreparedPlan.
     */
    entry = (RI_QueryHashEntry *) hash_search(ri_query_cache,
                                              (void *) key,
                                              HASH_ENTER, &found);
    Assert(!found || entry->plan == NULL);
    entry->plan = plan;
}


/* ----------
 * ri_KeysEqual -
 *
 *  Check if all key values in OLD and NEW are equal.
 *
 *  Note: at some point we might wish to redefine this as checking for
 *  "IS NOT DISTINCT" rather than "=", that is, allow two nulls to be
 *  considered equal.  Currently there is no need since all callers have
 *  previously found at least one of the rows to contain no nulls.
 * ----------
 */
static bool
ri_KeysEqual(Relation rel, HeapTuple oldtup, HeapTuple newtup,
             const RI_ConstraintInfo *riinfo, bool rel_is_pk)
{
    TupleDesc   tupdesc = RelationGetDescr(rel);
    const int16 *attnums;
    const Oid  *eq_oprs;
    int         i;

    if (rel_is_pk)
    {
        attnums = riinfo->pk_attnums;
        eq_oprs = riinfo->pp_eq_oprs;
    }
    else
    {
        attnums = riinfo->fk_attnums;
        eq_oprs = riinfo->ff_eq_oprs;
    }

    for (i = 0; i < riinfo->nkeys; i++)
    {
        Datum       oldvalue;
        Datum       newvalue;
        bool        isnull;

        /*
         * Get one attribute's oldvalue. If it is NULL - they're not equal.
         */
        oldvalue = heap_getattr(oldtup, attnums[i], tupdesc, &isnull);
        if (isnull)
            return false;

        /*
         * Get one attribute's newvalue. If it is NULL - they're not equal.
         */
        newvalue = heap_getattr(newtup, attnums[i], tupdesc, &isnull);
        if (isnull)
            return false;

        /*
         * Compare them with the appropriate equality operator.
         */
        if (!ri_AttributesEqual(eq_oprs[i], RIAttType(rel, attnums[i]),
                                oldvalue, newvalue))
            return false;
    }

    return true;
}


/* ----------
 * ri_AttributesEqual -
 *
 *  Call the appropriate equality comparison operator for two values.
 *
 *  NB: we have already checked that neither value is null.
 * ----------
 */
static bool
ri_AttributesEqual(Oid eq_opr, Oid typeid,
                   Datum oldvalue, Datum newvalue)
{
    RI_CompareHashEntry *entry = ri_HashCompareOp(eq_opr, typeid);

    /* Do we need to cast the values? */
    if (OidIsValid(entry->cast_func_finfo.fn_oid))
    {
        oldvalue = FunctionCall3(&entry->cast_func_finfo,
                                 oldvalue,
                                 Int32GetDatum(-1),     /* typmod */
                                 BoolGetDatum(false));  /* implicit coercion */
        newvalue = FunctionCall3(&entry->cast_func_finfo,
                                 newvalue,
                                 Int32GetDatum(-1),     /* typmod */
                                 BoolGetDatum(false));  /* implicit coercion */
    }

    /*
     * Apply the comparison operator.  We assume it doesn't care about
     * collations.
     */
    return DatumGetBool(FunctionCall2(&entry->eq_opr_finfo,
                                      oldvalue, newvalue));
}

/* ----------
 * ri_HashCompareOp -
 *
 *  See if we know how to compare two values, and create a new hash entry
 *  if not.
 * ----------
 */
static RI_CompareHashEntry *
ri_HashCompareOp(Oid eq_opr, Oid typeid)
{
    RI_CompareKey key;
    RI_CompareHashEntry *entry;
    bool        found;

    /*
     * On the first call initialize the hashtable
     */
    if (!ri_compare_cache)
        ri_InitHashTables();

    /*
     * Find or create a hash entry.  Note we're assuming RI_CompareKey
     * contains no struct padding.
     */
    key.eq_opr = eq_opr;
    key.typeid = typeid;
    entry = (RI_CompareHashEntry *) hash_search(ri_compare_cache,
                                                (void *) &key,
                                                HASH_ENTER, &found);
    if (!found)
        entry->valid = false;

    /*
     * If not already initialized, do so.  Since we'll keep this hash entry
     * for the life of the backend, put any subsidiary info for the function
     * cache structs into TopMemoryContext.
     */
    if (!entry->valid)
    {
        Oid         lefttype,
                    righttype,
                    castfunc;
        CoercionPathType pathtype;

        /* We always need to know how to call the equality operator */
        fmgr_info_cxt(get_opcode(eq_opr), &entry->eq_opr_finfo,
                      TopMemoryContext);

        /*
         * If we chose to use a cast from FK to PK type, we may have to apply
         * the cast function to get to the operator's input type.
         *
         * XXX eventually it would be good to support array-coercion cases
         * here and in ri_AttributesEqual().  At the moment there is no point
         * because cases involving nonidentical array types will be rejected
         * at constraint creation time.
         *
         * XXX perhaps also consider supporting CoerceViaIO?  No need at the
         * moment since that will never be generated for implicit coercions.
         */
        op_input_types(eq_opr, &lefttype, &righttype);
        Assert(lefttype == righttype);
        if (typeid == lefttype)
            castfunc = InvalidOid;      /* simplest case */
        else
        {
            pathtype = find_coercion_pathway(lefttype, typeid,
                                             COERCION_IMPLICIT,
                                             &castfunc);
            if (pathtype != COERCION_PATH_FUNC &&
                pathtype != COERCION_PATH_RELABELTYPE)
            {
                /*
                 * The declared input type of the eq_opr might be a
                 * polymorphic type such as ANYARRAY or ANYENUM, or other
                 * special cases such as RECORD; find_coercion_pathway
                 * currently doesn't subsume these special cases.
                 */
                if (!IsPolymorphicType(lefttype) &&
                    !IsBinaryCoercible(typeid, lefttype))
                    elog(ERROR, "no conversion function from %s to %s",
                         format_type_be(typeid),
                         format_type_be(lefttype));
            }
        }
        if (OidIsValid(castfunc))
            fmgr_info_cxt(castfunc, &entry->cast_func_finfo,
                          TopMemoryContext);
        else
            entry->cast_func_finfo.fn_oid = InvalidOid;
        entry->valid = true;
    }

    return entry;
}


/*
 * Given a trigger function OID, determine whether it is an RI trigger,
 * and if so whether it is attached to PK or FK relation.
 */
int
RI_FKey_trigger_type(Oid tgfoid)
{
    switch (tgfoid)
    {
        case F_RI_FKEY_CASCADE_DEL:
        case F_RI_FKEY_CASCADE_UPD:
        case F_RI_FKEY_RESTRICT_DEL:
        case F_RI_FKEY_RESTRICT_UPD:
        case F_RI_FKEY_SETNULL_DEL:
        case F_RI_FKEY_SETNULL_UPD:
        case F_RI_FKEY_SETDEFAULT_DEL:
        case F_RI_FKEY_SETDEFAULT_UPD:
        case F_RI_FKEY_NOACTION_DEL:
        case F_RI_FKEY_NOACTION_UPD:
            return RI_TRIGGER_PK;

        case F_RI_FKEY_CHECK_INS:
        case F_RI_FKEY_CHECK_UPD:
            return RI_TRIGGER_FK;
    }

    return RI_TRIGGER_NONE;
}