heap.c

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/*-------------------------------------------------------------------------
 *
 * heap.c
 *    code to create and destroy POSTGRES heap relations
 *
 * Portions Copyright (c) 1996-2013, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    src/backend/catalog/heap.c
 *
 *
 * INTERFACE ROUTINES
 *      heap_create()           - Create an uncataloged heap relation
 *      heap_create_with_catalog() - Create a cataloged relation
 *      heap_drop_with_catalog() - Removes named relation from catalogs
 *
 * NOTES
 *    this code taken from access/heap/create.c, which contains
 *    the old heap_create_with_catalog, amcreate, and amdestroy.
 *    those routines will soon call these routines using the function
 *    manager,
 *    just like the poorly named "NewXXX" routines do.  The
 *    "New" routines are all going to die soon, once and for all!
 *      -cim 1/13/91
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "access/htup_details.h"
#include "access/multixact.h"
#include "access/sysattr.h"
#include "access/transam.h"
#include "access/xact.h"
#include "catalog/catalog.h"
#include "catalog/dependency.h"
#include "catalog/heap.h"
#include "catalog/index.h"
#include "catalog/objectaccess.h"
#include "catalog/pg_attrdef.h"
#include "catalog/pg_collation.h"
#include "catalog/pg_constraint.h"
#include "catalog/pg_foreign_table.h"
#include "catalog/pg_inherits.h"
#include "catalog/pg_namespace.h"
#include "catalog/pg_statistic.h"
#include "catalog/pg_tablespace.h"
#include "catalog/pg_type.h"
#include "catalog/pg_type_fn.h"
#include "catalog/storage.h"
#include "catalog/storage_xlog.h"
#include "commands/tablecmds.h"
#include "commands/typecmds.h"
#include "miscadmin.h"
#include "nodes/nodeFuncs.h"
#include "optimizer/var.h"
#include "parser/parse_coerce.h"
#include "parser/parse_collate.h"
#include "parser/parse_expr.h"
#include "parser/parse_relation.h"
#include "storage/predicate.h"
#include "storage/smgr.h"
#include "utils/acl.h"
#include "utils/builtins.h"
#include "utils/fmgroids.h"
#include "utils/inval.h"
#include "utils/lsyscache.h"
#include "utils/rel.h"
#include "utils/snapmgr.h"
#include "utils/syscache.h"
#include "utils/tqual.h"


/* Potentially set by contrib/pg_upgrade_support functions */
Oid         binary_upgrade_next_heap_pg_class_oid = InvalidOid;
Oid         binary_upgrade_next_toast_pg_class_oid = InvalidOid;

static void AddNewRelationTuple(Relation pg_class_desc,
                    Relation new_rel_desc,
                    Oid new_rel_oid,
                    Oid new_type_oid,
                    Oid reloftype,
                    Oid relowner,
                    char relkind,
                    Datum relacl,
                    Datum reloptions);
static Oid AddNewRelationType(const char *typeName,
                   Oid typeNamespace,
                   Oid new_rel_oid,
                   char new_rel_kind,
                   Oid ownerid,
                   Oid new_row_type,
                   Oid new_array_type);
static void RelationRemoveInheritance(Oid relid);
static void StoreRelCheck(Relation rel, char *ccname, Node *expr,
              bool is_validated, bool is_local, int inhcount,
              bool is_no_inherit, bool is_internal);
static void StoreConstraints(Relation rel, List *cooked_constraints,
                             bool is_internal);
static bool MergeWithExistingConstraint(Relation rel, char *ccname, Node *expr,
                            bool allow_merge, bool is_local,
                            bool is_no_inherit);
static void SetRelationNumChecks(Relation rel, int numchecks);
static Node *cookConstraint(ParseState *pstate,
               Node *raw_constraint,
               char *relname);
static List *insert_ordered_unique_oid(List *list, Oid datum);


/* ----------------------------------------------------------------
 *              XXX UGLY HARD CODED BADNESS FOLLOWS XXX
 *
 *      these should all be moved to someplace in the lib/catalog
 *      module, if not obliterated first.
 * ----------------------------------------------------------------
 */


/*
 * Note:
 *      Should the system special case these attributes in the future?
 *      Advantage:  consume much less space in the ATTRIBUTE relation.
 *      Disadvantage:  special cases will be all over the place.
 */

/*
 * The initializers below do not include trailing variable length fields,
 * but that's OK - we're never going to reference anything beyond the
 * fixed-size portion of the structure anyway.
 */

static FormData_pg_attribute a1 = {
    0, {"ctid"}, TIDOID, 0, sizeof(ItemPointerData),
    SelfItemPointerAttributeNumber, 0, -1, -1,
    false, 'p', 's', true, false, false, true, 0
};

static FormData_pg_attribute a2 = {
    0, {"oid"}, OIDOID, 0, sizeof(Oid),
    ObjectIdAttributeNumber, 0, -1, -1,
    true, 'p', 'i', true, false, false, true, 0
};

static FormData_pg_attribute a3 = {
    0, {"xmin"}, XIDOID, 0, sizeof(TransactionId),
    MinTransactionIdAttributeNumber, 0, -1, -1,
    true, 'p', 'i', true, false, false, true, 0
};

static FormData_pg_attribute a4 = {
    0, {"cmin"}, CIDOID, 0, sizeof(CommandId),
    MinCommandIdAttributeNumber, 0, -1, -1,
    true, 'p', 'i', true, false, false, true, 0
};

static FormData_pg_attribute a5 = {
    0, {"xmax"}, XIDOID, 0, sizeof(TransactionId),
    MaxTransactionIdAttributeNumber, 0, -1, -1,
    true, 'p', 'i', true, false, false, true, 0
};

static FormData_pg_attribute a6 = {
    0, {"cmax"}, CIDOID, 0, sizeof(CommandId),
    MaxCommandIdAttributeNumber, 0, -1, -1,
    true, 'p', 'i', true, false, false, true, 0
};

/*
 * We decided to call this attribute "tableoid" rather than say
 * "classoid" on the basis that in the future there may be more than one
 * table of a particular class/type. In any case table is still the word
 * used in SQL.
 */
static FormData_pg_attribute a7 = {
    0, {"tableoid"}, OIDOID, 0, sizeof(Oid),
    TableOidAttributeNumber, 0, -1, -1,
    true, 'p', 'i', true, false, false, true, 0
};

static const Form_pg_attribute SysAtt[] = {&a1, &a2, &a3, &a4, &a5, &a6, &a7};

/*
 * This function returns a Form_pg_attribute pointer for a system attribute.
 * Note that we elog if the presented attno is invalid, which would only
 * happen if there's a problem upstream.
 */
Form_pg_attribute
SystemAttributeDefinition(AttrNumber attno, bool relhasoids)
{
    if (attno >= 0 || attno < -(int) lengthof(SysAtt))
        elog(ERROR, "invalid system attribute number %d", attno);
    if (attno == ObjectIdAttributeNumber && !relhasoids)
        elog(ERROR, "invalid system attribute number %d", attno);
    return SysAtt[-attno - 1];
}

/*
 * If the given name is a system attribute name, return a Form_pg_attribute
 * pointer for a prototype definition.  If not, return NULL.
 */
Form_pg_attribute
SystemAttributeByName(const char *attname, bool relhasoids)
{
    int         j;

    for (j = 0; j < (int) lengthof(SysAtt); j++)
    {
        Form_pg_attribute att = SysAtt[j];

        if (relhasoids || att->attnum != ObjectIdAttributeNumber)
        {
            if (strcmp(NameStr(att->attname), attname) == 0)
                return att;
        }
    }

    return NULL;
}


/* ----------------------------------------------------------------
 *              XXX END OF UGLY HARD CODED BADNESS XXX
 * ---------------------------------------------------------------- */


/* ----------------------------------------------------------------
 *      heap_create     - Create an uncataloged heap relation
 *
 *      Note API change: the caller must now always provide the OID
 *      to use for the relation.  The relfilenode may (and, normally,
 *      should) be left unspecified.
 *
 *      rel->rd_rel is initialized by RelationBuildLocalRelation,
 *      and is mostly zeroes at return.
 * ----------------------------------------------------------------
 */
Relation
heap_create(const char *relname,
            Oid relnamespace,
            Oid reltablespace,
            Oid relid,
            Oid relfilenode,
            TupleDesc tupDesc,
            char relkind,
            char relpersistence,
            bool shared_relation,
            bool mapped_relation)
{
    bool        create_storage;
    Relation    rel;

    /* The caller must have provided an OID for the relation. */
    Assert(OidIsValid(relid));

    /*
     * Decide if we need storage or not, and handle a couple other special
     * cases for particular relkinds.
     */
    switch (relkind)
    {
        case RELKIND_VIEW:
        case RELKIND_COMPOSITE_TYPE:
        case RELKIND_FOREIGN_TABLE:
            create_storage = false;

            /*
             * Force reltablespace to zero if the relation has no physical
             * storage.  This is mainly just for cleanliness' sake.
             */
            reltablespace = InvalidOid;
            break;
        case RELKIND_SEQUENCE:
            create_storage = true;

            /*
             * Force reltablespace to zero for sequences, since we don't
             * support moving them around into different tablespaces.
             */
            reltablespace = InvalidOid;
            break;
        default:
            create_storage = true;
            break;
    }

    /*
     * Unless otherwise requested, the physical ID (relfilenode) is initially
     * the same as the logical ID (OID).  When the caller did specify a
     * relfilenode, it already exists; do not attempt to create it.
     */
    if (OidIsValid(relfilenode))
        create_storage = false;
    else
        relfilenode = relid;

    /*
     * Never allow a pg_class entry to explicitly specify the database's
     * default tablespace in reltablespace; force it to zero instead. This
     * ensures that if the database is cloned with a different default
     * tablespace, the pg_class entry will still match where CREATE DATABASE
     * will put the physically copied relation.
     *
     * Yes, this is a bit of a hack.
     */
    if (reltablespace == MyDatabaseTableSpace)
        reltablespace = InvalidOid;

    /*
     * build the relcache entry.
     */
    rel = RelationBuildLocalRelation(relname,
                                     relnamespace,
                                     tupDesc,
                                     relid,
                                     relfilenode,
                                     reltablespace,
                                     shared_relation,
                                     mapped_relation,
                                     relpersistence,
                                     relkind);

    /*
     * Have the storage manager create the relation's disk file, if needed.
     *
     * We only create the main fork here, other forks will be created on
     * demand.
     */
    if (create_storage)
    {
        RelationOpenSmgr(rel);
        RelationCreateStorage(rel->rd_node, relpersistence);
    }

    return rel;
}

/* ----------------------------------------------------------------
 *      heap_create_with_catalog        - Create a cataloged relation
 *
 *      this is done in multiple steps:
 *
 *      1) CheckAttributeNamesTypes() is used to make certain the tuple
 *         descriptor contains a valid set of attribute names and types
 *
 *      2) pg_class is opened and get_relname_relid()
 *         performs a scan to ensure that no relation with the
 *         same name already exists.
 *
 *      3) heap_create() is called to create the new relation on disk.
 *
 *      4) TypeCreate() is called to define a new type corresponding
 *         to the new relation.
 *
 *      5) AddNewRelationTuple() is called to register the
 *         relation in pg_class.
 *
 *      6) AddNewAttributeTuples() is called to register the
 *         new relation's schema in pg_attribute.
 *
 *      7) StoreConstraints is called ()        - vadim 08/22/97
 *
 *      8) the relations are closed and the new relation's oid
 *         is returned.
 *
 * ----------------------------------------------------------------
 */

/* --------------------------------
 *      CheckAttributeNamesTypes
 *
 *      this is used to make certain the tuple descriptor contains a
 *      valid set of attribute names and datatypes.  a problem simply
 *      generates ereport(ERROR) which aborts the current transaction.
 * --------------------------------
 */
void
CheckAttributeNamesTypes(TupleDesc tupdesc, char relkind,
                         bool allow_system_table_mods)
{
    int         i;
    int         j;
    int         natts = tupdesc->natts;

    /* Sanity check on column count */
    if (natts < 0 || natts > MaxHeapAttributeNumber)
        ereport(ERROR,
                (errcode(ERRCODE_TOO_MANY_COLUMNS),
                 errmsg("tables can have at most %d columns",
                        MaxHeapAttributeNumber)));

    /*
     * first check for collision with system attribute names
     *
     * Skip this for a view or type relation, since those don't have system
     * attributes.
     */
    if (relkind != RELKIND_VIEW && relkind != RELKIND_COMPOSITE_TYPE)
    {
        for (i = 0; i < natts; i++)
        {
            if (SystemAttributeByName(NameStr(tupdesc->attrs[i]->attname),
                                      tupdesc->tdhasoid) != NULL)
                ereport(ERROR,
                        (errcode(ERRCODE_DUPLICATE_COLUMN),
                         errmsg("column name \"%s\" conflicts with a system column name",
                                NameStr(tupdesc->attrs[i]->attname))));
        }
    }

    /*
     * next check for repeated attribute names
     */
    for (i = 1; i < natts; i++)
    {
        for (j = 0; j < i; j++)
        {
            if (strcmp(NameStr(tupdesc->attrs[j]->attname),
                       NameStr(tupdesc->attrs[i]->attname)) == 0)
                ereport(ERROR,
                        (errcode(ERRCODE_DUPLICATE_COLUMN),
                         errmsg("column name \"%s\" specified more than once",
                                NameStr(tupdesc->attrs[j]->attname))));
        }
    }

    /*
     * next check the attribute types
     */
    for (i = 0; i < natts; i++)
    {
        CheckAttributeType(NameStr(tupdesc->attrs[i]->attname),
                           tupdesc->attrs[i]->atttypid,
                           tupdesc->attrs[i]->attcollation,
                           NIL, /* assume we're creating a new rowtype */
                           allow_system_table_mods);
    }
}

/* --------------------------------
 *      CheckAttributeType
 *
 *      Verify that the proposed datatype of an attribute is legal.
 *      This is needed mainly because there are types (and pseudo-types)
 *      in the catalogs that we do not support as elements of real tuples.
 *      We also check some other properties required of a table column.
 *
 * If the attribute is being proposed for addition to an existing table or
 * composite type, pass a one-element list of the rowtype OID as
 * containing_rowtypes.  When checking a to-be-created rowtype, it's
 * sufficient to pass NIL, because there could not be any recursive reference
 * to a not-yet-existing rowtype.
 * --------------------------------
 */
void
CheckAttributeType(const char *attname,
                   Oid atttypid, Oid attcollation,
                   List *containing_rowtypes,
                   bool allow_system_table_mods)
{
    char        att_typtype = get_typtype(atttypid);
    Oid         att_typelem;

    if (atttypid == UNKNOWNOID)
    {
        /*
         * Warn user, but don't fail, if column to be created has UNKNOWN type
         * (usually as a result of a 'retrieve into' - jolly)
         */
        ereport(WARNING,
                (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                 errmsg("column \"%s\" has type \"unknown\"", attname),
                 errdetail("Proceeding with relation creation anyway.")));
    }
    else if (att_typtype == TYPTYPE_PSEUDO)
    {
        /*
         * Refuse any attempt to create a pseudo-type column, except for a
         * special hack for pg_statistic: allow ANYARRAY when modifying system
         * catalogs (this allows creating pg_statistic and cloning it during
         * VACUUM FULL)
         */
        if (atttypid != ANYARRAYOID || !allow_system_table_mods)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                     errmsg("column \"%s\" has pseudo-type %s",
                            attname, format_type_be(atttypid))));
    }
    else if (att_typtype == TYPTYPE_DOMAIN)
    {
        /*
         * If it's a domain, recurse to check its base type.
         */
        CheckAttributeType(attname, getBaseType(atttypid), attcollation,
                           containing_rowtypes,
                           allow_system_table_mods);
    }
    else if (att_typtype == TYPTYPE_COMPOSITE)
    {
        /*
         * For a composite type, recurse into its attributes.
         */
        Relation    relation;
        TupleDesc   tupdesc;
        int         i;

        /*
         * Check for self-containment.  Eventually we might be able to allow
         * this (just return without complaint, if so) but it's not clear how
         * many other places would require anti-recursion defenses before it
         * would be safe to allow tables to contain their own rowtype.
         */
        if (list_member_oid(containing_rowtypes, atttypid))
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                errmsg("composite type %s cannot be made a member of itself",
                       format_type_be(atttypid))));

        containing_rowtypes = lcons_oid(atttypid, containing_rowtypes);

        relation = relation_open(get_typ_typrelid(atttypid), AccessShareLock);

        tupdesc = RelationGetDescr(relation);

        for (i = 0; i < tupdesc->natts; i++)
        {
            Form_pg_attribute attr = tupdesc->attrs[i];

            if (attr->attisdropped)
                continue;
            CheckAttributeType(NameStr(attr->attname),
                               attr->atttypid, attr->attcollation,
                               containing_rowtypes,
                               allow_system_table_mods);
        }

        relation_close(relation, AccessShareLock);

        containing_rowtypes = list_delete_first(containing_rowtypes);
    }
    else if (OidIsValid((att_typelem = get_element_type(atttypid))))
    {
        /*
         * Must recurse into array types, too, in case they are composite.
         */
        CheckAttributeType(attname, att_typelem, attcollation,
                           containing_rowtypes,
                           allow_system_table_mods);
    }

    /*
     * This might not be strictly invalid per SQL standard, but it is pretty
     * useless, and it cannot be dumped, so we must disallow it.
     */
    if (!OidIsValid(attcollation) && type_is_collatable(atttypid))
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                 errmsg("no collation was derived for column \"%s\" with collatable type %s",
                        attname, format_type_be(atttypid)),
        errhint("Use the COLLATE clause to set the collation explicitly.")));
}

/*
 * InsertPgAttributeTuple
 *      Construct and insert a new tuple in pg_attribute.
 *
 * Caller has already opened and locked pg_attribute.  new_attribute is the
 * attribute to insert (but we ignore attacl and attoptions, which are always
 * initialized to NULL).
 *
 * indstate is the index state for CatalogIndexInsert.  It can be passed as
 * NULL, in which case we'll fetch the necessary info.  (Don't do this when
 * inserting multiple attributes, because it's a tad more expensive.)
 */
void
InsertPgAttributeTuple(Relation pg_attribute_rel,
                       Form_pg_attribute new_attribute,
                       CatalogIndexState indstate)
{
    Datum       values[Natts_pg_attribute];
    bool        nulls[Natts_pg_attribute];
    HeapTuple   tup;

    /* This is a tad tedious, but way cleaner than what we used to do... */
    memset(values, 0, sizeof(values));
    memset(nulls, false, sizeof(nulls));

    values[Anum_pg_attribute_attrelid - 1] = ObjectIdGetDatum(new_attribute->attrelid);
    values[Anum_pg_attribute_attname - 1] = NameGetDatum(&new_attribute->attname);
    values[Anum_pg_attribute_atttypid - 1] = ObjectIdGetDatum(new_attribute->atttypid);
    values[Anum_pg_attribute_attstattarget - 1] = Int32GetDatum(new_attribute->attstattarget);
    values[Anum_pg_attribute_attlen - 1] = Int16GetDatum(new_attribute->attlen);
    values[Anum_pg_attribute_attnum - 1] = Int16GetDatum(new_attribute->attnum);
    values[Anum_pg_attribute_attndims - 1] = Int32GetDatum(new_attribute->attndims);
    values[Anum_pg_attribute_attcacheoff - 1] = Int32GetDatum(new_attribute->attcacheoff);
    values[Anum_pg_attribute_atttypmod - 1] = Int32GetDatum(new_attribute->atttypmod);
    values[Anum_pg_attribute_attbyval - 1] = BoolGetDatum(new_attribute->attbyval);
    values[Anum_pg_attribute_attstorage - 1] = CharGetDatum(new_attribute->attstorage);
    values[Anum_pg_attribute_attalign - 1] = CharGetDatum(new_attribute->attalign);
    values[Anum_pg_attribute_attnotnull - 1] = BoolGetDatum(new_attribute->attnotnull);
    values[Anum_pg_attribute_atthasdef - 1] = BoolGetDatum(new_attribute->atthasdef);
    values[Anum_pg_attribute_attisdropped - 1] = BoolGetDatum(new_attribute->attisdropped);
    values[Anum_pg_attribute_attislocal - 1] = BoolGetDatum(new_attribute->attislocal);
    values[Anum_pg_attribute_attinhcount - 1] = Int32GetDatum(new_attribute->attinhcount);
    values[Anum_pg_attribute_attcollation - 1] = ObjectIdGetDatum(new_attribute->attcollation);

    /* start out with empty permissions and empty options */
    nulls[Anum_pg_attribute_attacl - 1] = true;
    nulls[Anum_pg_attribute_attoptions - 1] = true;
    nulls[Anum_pg_attribute_attfdwoptions - 1] = true;

    tup = heap_form_tuple(RelationGetDescr(pg_attribute_rel), values, nulls);

    /* finally insert the new tuple, update the indexes, and clean up */
    simple_heap_insert(pg_attribute_rel, tup);

    if (indstate != NULL)
        CatalogIndexInsert(indstate, tup);
    else
        CatalogUpdateIndexes(pg_attribute_rel, tup);

    heap_freetuple(tup);
}

/* --------------------------------
 *      AddNewAttributeTuples
 *
 *      this registers the new relation's schema by adding
 *      tuples to pg_attribute.
 * --------------------------------
 */
static void
AddNewAttributeTuples(Oid new_rel_oid,
                      TupleDesc tupdesc,
                      char relkind,
                      bool oidislocal,
                      int oidinhcount)
{
    Form_pg_attribute attr;
    int         i;
    Relation    rel;
    CatalogIndexState indstate;
    int         natts = tupdesc->natts;
    ObjectAddress myself,
                referenced;

    /*
     * open pg_attribute and its indexes.
     */
    rel = heap_open(AttributeRelationId, RowExclusiveLock);

    indstate = CatalogOpenIndexes(rel);

    /*
     * First we add the user attributes.  This is also a convenient place to
     * add dependencies on their datatypes and collations.
     */
    for (i = 0; i < natts; i++)
    {
        attr = tupdesc->attrs[i];
        /* Fill in the correct relation OID */
        attr->attrelid = new_rel_oid;
        /* Make sure these are OK, too */
        attr->attstattarget = -1;
        attr->attcacheoff = -1;

        InsertPgAttributeTuple(rel, attr, indstate);

        /* Add dependency info */
        myself.classId = RelationRelationId;
        myself.objectId = new_rel_oid;
        myself.objectSubId = i + 1;
        referenced.classId = TypeRelationId;
        referenced.objectId = attr->atttypid;
        referenced.objectSubId = 0;
        recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);

        /* The default collation is pinned, so don't bother recording it */
        if (OidIsValid(attr->attcollation) &&
            attr->attcollation != DEFAULT_COLLATION_OID)
        {
            referenced.classId = CollationRelationId;
            referenced.objectId = attr->attcollation;
            referenced.objectSubId = 0;
            recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
        }
    }

    /*
     * Next we add the system attributes.  Skip OID if rel has no OIDs. Skip
     * all for a view or type relation.  We don't bother with making datatype
     * dependencies here, since presumably all these types are pinned.
     */
    if (relkind != RELKIND_VIEW && relkind != RELKIND_COMPOSITE_TYPE)
    {
        for (i = 0; i < (int) lengthof(SysAtt); i++)
        {
            FormData_pg_attribute attStruct;

            /* skip OID where appropriate */
            if (!tupdesc->tdhasoid &&
                SysAtt[i]->attnum == ObjectIdAttributeNumber)
                continue;

            memcpy(&attStruct, (char *) SysAtt[i], sizeof(FormData_pg_attribute));

            /* Fill in the correct relation OID in the copied tuple */
            attStruct.attrelid = new_rel_oid;

            /* Fill in correct inheritance info for the OID column */
            if (attStruct.attnum == ObjectIdAttributeNumber)
            {
                attStruct.attislocal = oidislocal;
                attStruct.attinhcount = oidinhcount;
            }

            InsertPgAttributeTuple(rel, &attStruct, indstate);
        }
    }

    /*
     * clean up
     */
    CatalogCloseIndexes(indstate);

    heap_close(rel, RowExclusiveLock);
}

/* --------------------------------
 *      InsertPgClassTuple
 *
 *      Construct and insert a new tuple in pg_class.
 *
 * Caller has already opened and locked pg_class.
 * Tuple data is taken from new_rel_desc->rd_rel, except for the
 * variable-width fields which are not present in a cached reldesc.
 * relacl and reloptions are passed in Datum form (to avoid having
 * to reference the data types in heap.h).  Pass (Datum) 0 to set them
 * to NULL.
 * --------------------------------
 */
void
InsertPgClassTuple(Relation pg_class_desc,
                   Relation new_rel_desc,
                   Oid new_rel_oid,
                   Datum relacl,
                   Datum reloptions)
{
    Form_pg_class rd_rel = new_rel_desc->rd_rel;
    Datum       values[Natts_pg_class];
    bool        nulls[Natts_pg_class];
    HeapTuple   tup;

    /* This is a tad tedious, but way cleaner than what we used to do... */
    memset(values, 0, sizeof(values));
    memset(nulls, false, sizeof(nulls));

    values[Anum_pg_class_relname - 1] = NameGetDatum(&rd_rel->relname);
    values[Anum_pg_class_relnamespace - 1] = ObjectIdGetDatum(rd_rel->relnamespace);
    values[Anum_pg_class_reltype - 1] = ObjectIdGetDatum(rd_rel->reltype);
    values[Anum_pg_class_reloftype - 1] = ObjectIdGetDatum(rd_rel->reloftype);
    values[Anum_pg_class_relowner - 1] = ObjectIdGetDatum(rd_rel->relowner);
    values[Anum_pg_class_relam - 1] = ObjectIdGetDatum(rd_rel->relam);
    values[Anum_pg_class_relfilenode - 1] = ObjectIdGetDatum(rd_rel->relfilenode);
    values[Anum_pg_class_reltablespace - 1] = ObjectIdGetDatum(rd_rel->reltablespace);
    values[Anum_pg_class_relpages - 1] = Int32GetDatum(rd_rel->relpages);
    values[Anum_pg_class_reltuples - 1] = Float4GetDatum(rd_rel->reltuples);
    values[Anum_pg_class_relallvisible - 1] = Int32GetDatum(rd_rel->relallvisible);
    values[Anum_pg_class_reltoastrelid - 1] = ObjectIdGetDatum(rd_rel->reltoastrelid);
    values[Anum_pg_class_reltoastidxid - 1] = ObjectIdGetDatum(rd_rel->reltoastidxid);
    values[Anum_pg_class_relhasindex - 1] = BoolGetDatum(rd_rel->relhasindex);
    values[Anum_pg_class_relisshared - 1] = BoolGetDatum(rd_rel->relisshared);
    values[Anum_pg_class_relpersistence - 1] = CharGetDatum(rd_rel->relpersistence);
    values[Anum_pg_class_relkind - 1] = CharGetDatum(rd_rel->relkind);
    values[Anum_pg_class_relnatts - 1] = Int16GetDatum(rd_rel->relnatts);
    values[Anum_pg_class_relchecks - 1] = Int16GetDatum(rd_rel->relchecks);
    values[Anum_pg_class_relhasoids - 1] = BoolGetDatum(rd_rel->relhasoids);
    values[Anum_pg_class_relhaspkey - 1] = BoolGetDatum(rd_rel->relhaspkey);
    values[Anum_pg_class_relhasrules - 1] = BoolGetDatum(rd_rel->relhasrules);
    values[Anum_pg_class_relhastriggers - 1] = BoolGetDatum(rd_rel->relhastriggers);
    values[Anum_pg_class_relhassubclass - 1] = BoolGetDatum(rd_rel->relhassubclass);
    values[Anum_pg_class_relfrozenxid - 1] = TransactionIdGetDatum(rd_rel->relfrozenxid);
    values[Anum_pg_class_relminmxid - 1] = MultiXactIdGetDatum(rd_rel->relminmxid);
    if (relacl != (Datum) 0)
        values[Anum_pg_class_relacl - 1] = relacl;
    else
        nulls[Anum_pg_class_relacl - 1] = true;
    if (reloptions != (Datum) 0)
        values[Anum_pg_class_reloptions - 1] = reloptions;
    else
        nulls[Anum_pg_class_reloptions - 1] = true;

    tup = heap_form_tuple(RelationGetDescr(pg_class_desc), values, nulls);

    /*
     * The new tuple must have the oid already chosen for the rel.  Sure would
     * be embarrassing to do this sort of thing in polite company.
     */
    HeapTupleSetOid(tup, new_rel_oid);

    /* finally insert the new tuple, update the indexes, and clean up */
    simple_heap_insert(pg_class_desc, tup);

    CatalogUpdateIndexes(pg_class_desc, tup);

    heap_freetuple(tup);
}

/* --------------------------------
 *      AddNewRelationTuple
 *
 *      this registers the new relation in the catalogs by
 *      adding a tuple to pg_class.
 * --------------------------------
 */
static void
AddNewRelationTuple(Relation pg_class_desc,
                    Relation new_rel_desc,
                    Oid new_rel_oid,
                    Oid new_type_oid,
                    Oid reloftype,
                    Oid relowner,
                    char relkind,
                    Datum relacl,
                    Datum reloptions)
{
    Form_pg_class new_rel_reltup;

    /*
     * first we update some of the information in our uncataloged relation's
     * relation descriptor.
     */
    new_rel_reltup = new_rel_desc->rd_rel;

    switch (relkind)
    {
        case RELKIND_RELATION:
        case RELKIND_MATVIEW:
        case RELKIND_INDEX:
        case RELKIND_TOASTVALUE:
            /* The relation is real, but as yet empty */
            new_rel_reltup->relpages = 0;
            new_rel_reltup->reltuples = 0;
            new_rel_reltup->relallvisible = 0;
            break;
        case RELKIND_SEQUENCE:
            /* Sequences always have a known size */
            new_rel_reltup->relpages = 1;
            new_rel_reltup->reltuples = 1;
            new_rel_reltup->relallvisible = 0;
            break;
        default:
            /* Views, etc, have no disk storage */
            new_rel_reltup->relpages = 0;
            new_rel_reltup->reltuples = 0;
            new_rel_reltup->relallvisible = 0;
            break;
    }

    /* Initialize relfrozenxid and relminmxid */
    if (relkind == RELKIND_RELATION ||
        relkind == RELKIND_MATVIEW ||
        relkind == RELKIND_TOASTVALUE)
    {
        /*
         * Initialize to the minimum XID that could put tuples in the table.
         * We know that no xacts older than RecentXmin are still running, so
         * that will do.
         */
        new_rel_reltup->relfrozenxid = RecentXmin;
        /*
         * Similarly, initialize the minimum Multixact to the first value that
         * could possibly be stored in tuples in the table.  Running
         * transactions could reuse values from their local cache, so we are
         * careful to consider all currently running multis.
         *
         * XXX this could be refined further, but is it worth the hassle?
         */
        new_rel_reltup->relminmxid = GetOldestMultiXactId();
    }
    else
    {
        /*
         * Other relation types will not contain XIDs, so set relfrozenxid to
         * InvalidTransactionId.  (Note: a sequence does contain a tuple, but
         * we force its xmin to be FrozenTransactionId always; see
         * commands/sequence.c.)
         */
        new_rel_reltup->relfrozenxid = InvalidTransactionId;
        new_rel_reltup->relfrozenxid = InvalidMultiXactId;
    }

    new_rel_reltup->relowner = relowner;
    new_rel_reltup->reltype = new_type_oid;
    new_rel_reltup->reloftype = reloftype;

    new_rel_desc->rd_att->tdtypeid = new_type_oid;

    /* Now build and insert the tuple */
    InsertPgClassTuple(pg_class_desc, new_rel_desc, new_rel_oid,
                       relacl, reloptions);
}


/* --------------------------------
 *      AddNewRelationType -
 *
 *      define a composite type corresponding to the new relation
 * --------------------------------
 */
static Oid
AddNewRelationType(const char *typeName,
                   Oid typeNamespace,
                   Oid new_rel_oid,
                   char new_rel_kind,
                   Oid ownerid,
                   Oid new_row_type,
                   Oid new_array_type)
{
    return
        TypeCreate(new_row_type,    /* optional predetermined OID */
                   typeName,    /* type name */
                   typeNamespace,       /* type namespace */
                   new_rel_oid, /* relation oid */
                   new_rel_kind,    /* relation kind */
                   ownerid,     /* owner's ID */
                   -1,          /* internal size (varlena) */
                   TYPTYPE_COMPOSITE,   /* type-type (composite) */
                   TYPCATEGORY_COMPOSITE,       /* type-category (ditto) */
                   false,       /* composite types are never preferred */
                   DEFAULT_TYPDELIM,    /* default array delimiter */
                   F_RECORD_IN, /* input procedure */
                   F_RECORD_OUT,    /* output procedure */
                   F_RECORD_RECV,       /* receive procedure */
                   F_RECORD_SEND,       /* send procedure */
                   InvalidOid,  /* typmodin procedure - none */
                   InvalidOid,  /* typmodout procedure - none */
                   InvalidOid,  /* analyze procedure - default */
                   InvalidOid,  /* array element type - irrelevant */
                   false,       /* this is not an array type */
                   new_array_type,      /* array type if any */
                   InvalidOid,  /* domain base type - irrelevant */
                   NULL,        /* default value - none */
                   NULL,        /* default binary representation */
                   false,       /* passed by reference */
                   'd',         /* alignment - must be the largest! */
                   'x',         /* fully TOASTable */
                   -1,          /* typmod */
                   0,           /* array dimensions for typBaseType */
                   false,       /* Type NOT NULL */
                   InvalidOid); /* rowtypes never have a collation */
}

/* --------------------------------
 *      heap_create_with_catalog
 *
 *      creates a new cataloged relation.  see comments above.
 *
 * Arguments:
 *  relname: name to give to new rel
 *  relnamespace: OID of namespace it goes in
 *  reltablespace: OID of tablespace it goes in
 *  relid: OID to assign to new rel, or InvalidOid to select a new OID
 *  reltypeid: OID to assign to rel's rowtype, or InvalidOid to select one
 *  reloftypeid: if a typed table, OID of underlying type; else InvalidOid
 *  ownerid: OID of new rel's owner
 *  tupdesc: tuple descriptor (source of column definitions)
 *  cooked_constraints: list of precooked check constraints and defaults
 *  relkind: relkind for new rel
 *  relpersistence: rel's persistence status (permanent, temp, or unlogged)
 *  shared_relation: TRUE if it's to be a shared relation
 *  mapped_relation: TRUE if the relation will use the relfilenode map
 *  oidislocal: TRUE if oid column (if any) should be marked attislocal
 *  oidinhcount: attinhcount to assign to oid column (if any)
 *  oncommit: ON COMMIT marking (only relevant if it's a temp table)
 *  reloptions: reloptions in Datum form, or (Datum) 0 if none
 *  use_user_acl: TRUE if should look for user-defined default permissions;
 *      if FALSE, relacl is always set NULL
 *  allow_system_table_mods: TRUE to allow creation in system namespaces
 *
 * Returns the OID of the new relation
 * --------------------------------
 */
Oid
heap_create_with_catalog(const char *relname,
                         Oid relnamespace,
                         Oid reltablespace,
                         Oid relid,
                         Oid reltypeid,
                         Oid reloftypeid,
                         Oid ownerid,
                         TupleDesc tupdesc,
                         List *cooked_constraints,
                         char relkind,
                         char relpersistence,
                         bool shared_relation,
                         bool mapped_relation,
                         bool oidislocal,
                         int oidinhcount,
                         OnCommitAction oncommit,
                         Datum reloptions,
                         bool use_user_acl,
                         bool allow_system_table_mods,
                         bool is_internal)
{
    Relation    pg_class_desc;
    Relation    new_rel_desc;
    Acl        *relacl;
    Oid         existing_relid;
    Oid         old_type_oid;
    Oid         new_type_oid;
    Oid         new_array_oid = InvalidOid;

    pg_class_desc = heap_open(RelationRelationId, RowExclusiveLock);

    /*
     * sanity checks
     */
    Assert(IsNormalProcessingMode() || IsBootstrapProcessingMode());

    CheckAttributeNamesTypes(tupdesc, relkind, allow_system_table_mods);

    /*
     * This would fail later on anyway, if the relation already exists.  But
     * by catching it here we can emit a nicer error message.
     */
    existing_relid = get_relname_relid(relname, relnamespace);
    if (existing_relid != InvalidOid)
        ereport(ERROR,
                (errcode(ERRCODE_DUPLICATE_TABLE),
                 errmsg("relation \"%s\" already exists", relname)));

    /*
     * Since we are going to create a rowtype as well, also check for
     * collision with an existing type name.  If there is one and it's an
     * autogenerated array, we can rename it out of the way; otherwise we can
     * at least give a good error message.
     */
    old_type_oid = GetSysCacheOid2(TYPENAMENSP,
                                   CStringGetDatum(relname),
                                   ObjectIdGetDatum(relnamespace));
    if (OidIsValid(old_type_oid))
    {
        if (!moveArrayTypeName(old_type_oid, relname, relnamespace))
            ereport(ERROR,
                    (errcode(ERRCODE_DUPLICATE_OBJECT),
                     errmsg("type \"%s\" already exists", relname),
               errhint("A relation has an associated type of the same name, "
                       "so you must use a name that doesn't conflict "
                       "with any existing type.")));
    }

    /*
     * Shared relations must be in pg_global (last-ditch check)
     */
    if (shared_relation && reltablespace != GLOBALTABLESPACE_OID)
        elog(ERROR, "shared relations must be placed in pg_global tablespace");

    /*
     * Allocate an OID for the relation, unless we were told what to use.
     *
     * The OID will be the relfilenode as well, so make sure it doesn't
     * collide with either pg_class OIDs or existing physical files.
     */
    if (!OidIsValid(relid))
    {
        /*
         * Use binary-upgrade override for pg_class.oid/relfilenode, if
         * supplied.
         */
        if (IsBinaryUpgrade &&
            OidIsValid(binary_upgrade_next_heap_pg_class_oid) &&
            (relkind == RELKIND_RELATION || relkind == RELKIND_SEQUENCE ||
             relkind == RELKIND_VIEW || relkind == RELKIND_MATVIEW ||
             relkind == RELKIND_COMPOSITE_TYPE || relkind == RELKIND_FOREIGN_TABLE))
        {
            relid = binary_upgrade_next_heap_pg_class_oid;
            binary_upgrade_next_heap_pg_class_oid = InvalidOid;
        }
        else if (IsBinaryUpgrade &&
                 OidIsValid(binary_upgrade_next_toast_pg_class_oid) &&
                 relkind == RELKIND_TOASTVALUE)
        {
            relid = binary_upgrade_next_toast_pg_class_oid;
            binary_upgrade_next_toast_pg_class_oid = InvalidOid;
        }
        else
            relid = GetNewRelFileNode(reltablespace, pg_class_desc,
                                      relpersistence);
    }

    /*
     * Determine the relation's initial permissions.
     */
    if (use_user_acl)
    {
        switch (relkind)
        {
            case RELKIND_RELATION:
            case RELKIND_VIEW:
            case RELKIND_MATVIEW:
            case RELKIND_FOREIGN_TABLE:
                relacl = get_user_default_acl(ACL_OBJECT_RELATION, ownerid,
                                              relnamespace);
                break;
            case RELKIND_SEQUENCE:
                relacl = get_user_default_acl(ACL_OBJECT_SEQUENCE, ownerid,
                                              relnamespace);
                break;
            default:
                relacl = NULL;
                break;
        }
    }
    else
        relacl = NULL;

    /*
     * Create the relcache entry (mostly dummy at this point) and the physical
     * disk file.  (If we fail further down, it's the smgr's responsibility to
     * remove the disk file again.)
     */
    new_rel_desc = heap_create(relname,
                               relnamespace,
                               reltablespace,
                               relid,
                               InvalidOid,
                               tupdesc,
                               relkind,
                               relpersistence,
                               shared_relation,
                               mapped_relation);

    Assert(relid == RelationGetRelid(new_rel_desc));

    /*
     * Decide whether to create an array type over the relation's rowtype. We
     * do not create any array types for system catalogs (ie, those made
     * during initdb).  We create array types for regular relations, views,
     * composite types and foreign tables ... but not, eg, for toast tables or
     * sequences.
     */
    if (IsUnderPostmaster && (relkind == RELKIND_RELATION ||
                              relkind == RELKIND_VIEW ||
                              relkind == RELKIND_MATVIEW ||
                              relkind == RELKIND_FOREIGN_TABLE ||
                              relkind == RELKIND_COMPOSITE_TYPE))
        new_array_oid = AssignTypeArrayOid();

    /*
     * Since defining a relation also defines a complex type, we add a new
     * system type corresponding to the new relation.  The OID of the type can
     * be preselected by the caller, but if reltypeid is InvalidOid, we'll
     * generate a new OID for it.
     *
     * NOTE: we could get a unique-index failure here, in case someone else is
     * creating the same type name in parallel but hadn't committed yet when
     * we checked for a duplicate name above.
     */
    new_type_oid = AddNewRelationType(relname,
                                      relnamespace,
                                      relid,
                                      relkind,
                                      ownerid,
                                      reltypeid,
                                      new_array_oid);

    /*
     * Now make the array type if wanted.
     */
    if (OidIsValid(new_array_oid))
    {
        char       *relarrayname;

        relarrayname = makeArrayTypeName(relname, relnamespace);

        TypeCreate(new_array_oid,       /* force the type's OID to this */
                   relarrayname,    /* Array type name */
                   relnamespace,    /* Same namespace as parent */
                   InvalidOid,  /* Not composite, no relationOid */
                   0,           /* relkind, also N/A here */
                   ownerid,     /* owner's ID */
                   -1,          /* Internal size (varlena) */
                   TYPTYPE_BASE,    /* Not composite - typelem is */
                   TYPCATEGORY_ARRAY,   /* type-category (array) */
                   false,       /* array types are never preferred */
                   DEFAULT_TYPDELIM,    /* default array delimiter */
                   F_ARRAY_IN,  /* array input proc */
                   F_ARRAY_OUT, /* array output proc */
                   F_ARRAY_RECV,    /* array recv (bin) proc */
                   F_ARRAY_SEND,    /* array send (bin) proc */
                   InvalidOid,  /* typmodin procedure - none */
                   InvalidOid,  /* typmodout procedure - none */
                   F_ARRAY_TYPANALYZE,  /* array analyze procedure */
                   new_type_oid,    /* array element type - the rowtype */
                   true,        /* yes, this is an array type */
                   InvalidOid,  /* this has no array type */
                   InvalidOid,  /* domain base type - irrelevant */
                   NULL,        /* default value - none */
                   NULL,        /* default binary representation */
                   false,       /* passed by reference */
                   'd',         /* alignment - must be the largest! */
                   'x',         /* fully TOASTable */
                   -1,          /* typmod */
                   0,           /* array dimensions for typBaseType */
                   false,       /* Type NOT NULL */
                   InvalidOid); /* rowtypes never have a collation */

        pfree(relarrayname);
    }

    /*
     * now create an entry in pg_class for the relation.
     *
     * NOTE: we could get a unique-index failure here, in case someone else is
     * creating the same relation name in parallel but hadn't committed yet
     * when we checked for a duplicate name above.
     */
    AddNewRelationTuple(pg_class_desc,
                        new_rel_desc,
                        relid,
                        new_type_oid,
                        reloftypeid,
                        ownerid,
                        relkind,
                        PointerGetDatum(relacl),
                        reloptions);

    /*
     * now add tuples to pg_attribute for the attributes in our new relation.
     */
    AddNewAttributeTuples(relid, new_rel_desc->rd_att, relkind,
                          oidislocal, oidinhcount);

    /*
     * Make a dependency link to force the relation to be deleted if its
     * namespace is.  Also make a dependency link to its owner, as well as
     * dependencies for any roles mentioned in the default ACL.
     *
     * For composite types, these dependencies are tracked for the pg_type
     * entry, so we needn't record them here.  Likewise, TOAST tables don't
     * need a namespace dependency (they live in a pinned namespace) nor an
     * owner dependency (they depend indirectly through the parent table), nor
     * should they have any ACL entries.  The same applies for extension
     * dependencies.
     *
     * If it's a temp table, we do not make it an extension member; this
     * prevents the unintuitive result that deletion of the temp table at
     * session end would make the whole extension go away.
     *
     * Also, skip this in bootstrap mode, since we don't make dependencies
     * while bootstrapping.
     */
    if (relkind != RELKIND_COMPOSITE_TYPE &&
        relkind != RELKIND_TOASTVALUE &&
        !IsBootstrapProcessingMode())
    {
        ObjectAddress myself,
                    referenced;

        myself.classId = RelationRelationId;
        myself.objectId = relid;
        myself.objectSubId = 0;
        referenced.classId = NamespaceRelationId;
        referenced.objectId = relnamespace;
        referenced.objectSubId = 0;
        recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);

        recordDependencyOnOwner(RelationRelationId, relid, ownerid);

        if (relpersistence != RELPERSISTENCE_TEMP)
            recordDependencyOnCurrentExtension(&myself, false);

        if (reloftypeid)
        {
            referenced.classId = TypeRelationId;
            referenced.objectId = reloftypeid;
            referenced.objectSubId = 0;
            recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
        }

        if (relacl != NULL)
        {
            int         nnewmembers;
            Oid        *newmembers;

            nnewmembers = aclmembers(relacl, &newmembers);
            updateAclDependencies(RelationRelationId, relid, 0,
                                  ownerid,
                                  0, NULL,
                                  nnewmembers, newmembers);
        }
    }

    /* Post creation hook for new relation */
    InvokeObjectPostCreateHookArg(RelationRelationId, relid, 0, is_internal);

    /*
     * Store any supplied constraints and defaults.
     *
     * NB: this may do a CommandCounterIncrement and rebuild the relcache
     * entry, so the relation must be valid and self-consistent at this point.
     * In particular, there are not yet constraints and defaults anywhere.
     */
    StoreConstraints(new_rel_desc, cooked_constraints, is_internal);

    /*
     * If there's a special on-commit action, remember it
     */
    if (oncommit != ONCOMMIT_NOOP)
        register_on_commit_action(relid, oncommit);

    if (relpersistence == RELPERSISTENCE_UNLOGGED)
    {
        Assert(relkind == RELKIND_RELATION || relkind == RELKIND_MATVIEW ||
               relkind == RELKIND_TOASTVALUE);
        heap_create_init_fork(new_rel_desc);
    }

    /*
     * ok, the relation has been cataloged, so close our relations and return
     * the OID of the newly created relation.
     */
    heap_close(new_rel_desc, NoLock);   /* do not unlock till end of xact */
    heap_close(pg_class_desc, RowExclusiveLock);

    return relid;
}

/*
 * Set up an init fork for an unlogged table so that it can be correctly
 * reinitialized on restart.  Since we're going to do an immediate sync, we
 * only need to xlog this if archiving or streaming is enabled.  And the
 * immediate sync is required, because otherwise there's no guarantee that
 * this will hit the disk before the next checkpoint moves the redo pointer.
 */
void
heap_create_init_fork(Relation rel)
{
    RelationOpenSmgr(rel);
    smgrcreate(rel->rd_smgr, INIT_FORKNUM, false);
    if (XLogIsNeeded())
        log_smgrcreate(&rel->rd_smgr->smgr_rnode.node, INIT_FORKNUM);
    smgrimmedsync(rel->rd_smgr, INIT_FORKNUM);
}

/*
 * Check whether a materialized view is in an initial, unloaded state.
 *
 * The check here must match what is set up in heap_create_init_fork().
 * Currently the init fork is an empty file.  A missing heap is also
 * considered to be unloaded.
 */
bool
heap_is_matview_init_state(Relation rel)
{
    Assert(rel->rd_rel->relkind == RELKIND_MATVIEW);

    RelationOpenSmgr(rel);

    if (!smgrexists(rel->rd_smgr, MAIN_FORKNUM))
        return true;

    return (smgrnblocks(rel->rd_smgr, MAIN_FORKNUM) < 1);
}

/*
 *      RelationRemoveInheritance
 *
 * Formerly, this routine checked for child relations and aborted the
 * deletion if any were found.  Now we rely on the dependency mechanism
 * to check for or delete child relations.  By the time we get here,
 * there are no children and we need only remove any pg_inherits rows
 * linking this relation to its parent(s).
 */
static void
RelationRemoveInheritance(Oid relid)
{
    Relation    catalogRelation;
    SysScanDesc scan;
    ScanKeyData key;
    HeapTuple   tuple;

    catalogRelation = heap_open(InheritsRelationId, RowExclusiveLock);

    ScanKeyInit(&key,
                Anum_pg_inherits_inhrelid,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(relid));

    scan = systable_beginscan(catalogRelation, InheritsRelidSeqnoIndexId, true,
                              SnapshotNow, 1, &key);

    while (HeapTupleIsValid(tuple = systable_getnext(scan)))
        simple_heap_delete(catalogRelation, &tuple->t_self);

    systable_endscan(scan);
    heap_close(catalogRelation, RowExclusiveLock);
}

/*
 *      DeleteRelationTuple
 *
 * Remove pg_class row for the given relid.
 *
 * Note: this is shared by relation deletion and index deletion.  It's
 * not intended for use anyplace else.
 */
void
DeleteRelationTuple(Oid relid)
{
    Relation    pg_class_desc;
    HeapTuple   tup;

    /* Grab an appropriate lock on the pg_class relation */
    pg_class_desc = heap_open(RelationRelationId, RowExclusiveLock);

    tup = SearchSysCache1(RELOID, ObjectIdGetDatum(relid));
    if (!HeapTupleIsValid(tup))
        elog(ERROR, "cache lookup failed for relation %u", relid);

    /* delete the relation tuple from pg_class, and finish up */
    simple_heap_delete(pg_class_desc, &tup->t_self);

    ReleaseSysCache(tup);

    heap_close(pg_class_desc, RowExclusiveLock);
}

/*
 *      DeleteAttributeTuples
 *
 * Remove pg_attribute rows for the given relid.
 *
 * Note: this is shared by relation deletion and index deletion.  It's
 * not intended for use anyplace else.
 */
void
DeleteAttributeTuples(Oid relid)
{
    Relation    attrel;
    SysScanDesc scan;
    ScanKeyData key[1];
    HeapTuple   atttup;

    /* Grab an appropriate lock on the pg_attribute relation */
    attrel = heap_open(AttributeRelationId, RowExclusiveLock);

    /* Use the index to scan only attributes of the target relation */
    ScanKeyInit(&key[0],
                Anum_pg_attribute_attrelid,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(relid));

    scan = systable_beginscan(attrel, AttributeRelidNumIndexId, true,
                              SnapshotNow, 1, key);

    /* Delete all the matching tuples */
    while ((atttup = systable_getnext(scan)) != NULL)
        simple_heap_delete(attrel, &atttup->t_self);

    /* Clean up after the scan */
    systable_endscan(scan);
    heap_close(attrel, RowExclusiveLock);
}

/*
 *      DeleteSystemAttributeTuples
 *
 * Remove pg_attribute rows for system columns of the given relid.
 *
 * Note: this is only used when converting a table to a view.  Views don't
 * have system columns, so we should remove them from pg_attribute.
 */
void
DeleteSystemAttributeTuples(Oid relid)
{
    Relation    attrel;
    SysScanDesc scan;
    ScanKeyData key[2];
    HeapTuple   atttup;

    /* Grab an appropriate lock on the pg_attribute relation */
    attrel = heap_open(AttributeRelationId, RowExclusiveLock);

    /* Use the index to scan only system attributes of the target relation */
    ScanKeyInit(&key[0],
                Anum_pg_attribute_attrelid,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(relid));
    ScanKeyInit(&key[1],
                Anum_pg_attribute_attnum,
                BTLessEqualStrategyNumber, F_INT2LE,
                Int16GetDatum(0));

    scan = systable_beginscan(attrel, AttributeRelidNumIndexId, true,
                              SnapshotNow, 2, key);

    /* Delete all the matching tuples */
    while ((atttup = systable_getnext(scan)) != NULL)
        simple_heap_delete(attrel, &atttup->t_self);

    /* Clean up after the scan */
    systable_endscan(scan);
    heap_close(attrel, RowExclusiveLock);
}

/*
 *      RemoveAttributeById
 *
 * This is the guts of ALTER TABLE DROP COLUMN: actually mark the attribute
 * deleted in pg_attribute.  We also remove pg_statistic entries for it.
 * (Everything else needed, such as getting rid of any pg_attrdef entry,
 * is handled by dependency.c.)
 */
void
RemoveAttributeById(Oid relid, AttrNumber attnum)
{
    Relation    rel;
    Relation    attr_rel;
    HeapTuple   tuple;
    Form_pg_attribute attStruct;
    char        newattname[NAMEDATALEN];

    /*
     * Grab an exclusive lock on the target table, which we will NOT release
     * until end of transaction.  (In the simple case where we are directly
     * dropping this column, AlterTableDropColumn already did this ... but
     * when cascading from a drop of some other object, we may not have any
     * lock.)
     */
    rel = relation_open(relid, AccessExclusiveLock);

    attr_rel = heap_open(AttributeRelationId, RowExclusiveLock);

    tuple = SearchSysCacheCopy2(ATTNUM,
                                ObjectIdGetDatum(relid),
                                Int16GetDatum(attnum));
    if (!HeapTupleIsValid(tuple))       /* shouldn't happen */
        elog(ERROR, "cache lookup failed for attribute %d of relation %u",
             attnum, relid);
    attStruct = (Form_pg_attribute) GETSTRUCT(tuple);

    if (attnum < 0)
    {
        /* System attribute (probably OID) ... just delete the row */

        simple_heap_delete(attr_rel, &tuple->t_self);
    }
    else
    {
        /* Dropping user attributes is lots harder */

        /* Mark the attribute as dropped */
        attStruct->attisdropped = true;

        /*
         * Set the type OID to invalid.  A dropped attribute's type link
         * cannot be relied on (once the attribute is dropped, the type might
         * be too). Fortunately we do not need the type row --- the only
         * really essential information is the type's typlen and typalign,
         * which are preserved in the attribute's attlen and attalign.  We set
         * atttypid to zero here as a means of catching code that incorrectly
         * expects it to be valid.
         */
        attStruct->atttypid = InvalidOid;

        /* Remove any NOT NULL constraint the column may have */
        attStruct->attnotnull = false;

        /* We don't want to keep stats for it anymore */
        attStruct->attstattarget = 0;

        /*
         * Change the column name to something that isn't likely to conflict
         */
        snprintf(newattname, sizeof(newattname),
                 "........pg.dropped.%d........", attnum);
        namestrcpy(&(attStruct->attname), newattname);

        simple_heap_update(attr_rel, &tuple->t_self, tuple);

        /* keep the system catalog indexes current */
        CatalogUpdateIndexes(attr_rel, tuple);
    }

    /*
     * Because updating the pg_attribute row will trigger a relcache flush for
     * the target relation, we need not do anything else to notify other
     * backends of the change.
     */

    heap_close(attr_rel, RowExclusiveLock);

    if (attnum > 0)
        RemoveStatistics(relid, attnum);

    relation_close(rel, NoLock);
}

/*
 *      RemoveAttrDefault
 *
 * If the specified relation/attribute has a default, remove it.
 * (If no default, raise error if complain is true, else return quietly.)
 */
void
RemoveAttrDefault(Oid relid, AttrNumber attnum,
                  DropBehavior behavior, bool complain, bool internal)
{
    Relation    attrdef_rel;
    ScanKeyData scankeys[2];
    SysScanDesc scan;
    HeapTuple   tuple;
    bool        found = false;

    attrdef_rel = heap_open(AttrDefaultRelationId, RowExclusiveLock);

    ScanKeyInit(&scankeys[0],
                Anum_pg_attrdef_adrelid,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(relid));
    ScanKeyInit(&scankeys[1],
                Anum_pg_attrdef_adnum,
                BTEqualStrategyNumber, F_INT2EQ,
                Int16GetDatum(attnum));

    scan = systable_beginscan(attrdef_rel, AttrDefaultIndexId, true,
                              SnapshotNow, 2, scankeys);

    /* There should be at most one matching tuple, but we loop anyway */
    while (HeapTupleIsValid(tuple = systable_getnext(scan)))
    {
        ObjectAddress object;

        object.classId = AttrDefaultRelationId;
        object.objectId = HeapTupleGetOid(tuple);
        object.objectSubId = 0;

        performDeletion(&object, behavior,
                        internal ? PERFORM_DELETION_INTERNAL : 0);

        found = true;
    }

    systable_endscan(scan);
    heap_close(attrdef_rel, RowExclusiveLock);

    if (complain && !found)
        elog(ERROR, "could not find attrdef tuple for relation %u attnum %d",
             relid, attnum);
}

/*
 *      RemoveAttrDefaultById
 *
 * Remove a pg_attrdef entry specified by OID.  This is the guts of
 * attribute-default removal.  Note it should be called via performDeletion,
 * not directly.
 */
void
RemoveAttrDefaultById(Oid attrdefId)
{
    Relation    attrdef_rel;
    Relation    attr_rel;
    Relation    myrel;
    ScanKeyData scankeys[1];
    SysScanDesc scan;
    HeapTuple   tuple;
    Oid         myrelid;
    AttrNumber  myattnum;

    /* Grab an appropriate lock on the pg_attrdef relation */
    attrdef_rel = heap_open(AttrDefaultRelationId, RowExclusiveLock);

    /* Find the pg_attrdef tuple */
    ScanKeyInit(&scankeys[0],
                ObjectIdAttributeNumber,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(attrdefId));

    scan = systable_beginscan(attrdef_rel, AttrDefaultOidIndexId, true,
                              SnapshotNow, 1, scankeys);

    tuple = systable_getnext(scan);
    if (!HeapTupleIsValid(tuple))
        elog(ERROR, "could not find tuple for attrdef %u", attrdefId);

    myrelid = ((Form_pg_attrdef) GETSTRUCT(tuple))->adrelid;
    myattnum = ((Form_pg_attrdef) GETSTRUCT(tuple))->adnum;

    /* Get an exclusive lock on the relation owning the attribute */
    myrel = relation_open(myrelid, AccessExclusiveLock);

    /* Now we can delete the pg_attrdef row */
    simple_heap_delete(attrdef_rel, &tuple->t_self);

    systable_endscan(scan);
    heap_close(attrdef_rel, RowExclusiveLock);

    /* Fix the pg_attribute row */
    attr_rel = heap_open(AttributeRelationId, RowExclusiveLock);

    tuple = SearchSysCacheCopy2(ATTNUM,
                                ObjectIdGetDatum(myrelid),
                                Int16GetDatum(myattnum));
    if (!HeapTupleIsValid(tuple))       /* shouldn't happen */
        elog(ERROR, "cache lookup failed for attribute %d of relation %u",
             myattnum, myrelid);

    ((Form_pg_attribute) GETSTRUCT(tuple))->atthasdef = false;

    simple_heap_update(attr_rel, &tuple->t_self, tuple);

    /* keep the system catalog indexes current */
    CatalogUpdateIndexes(attr_rel, tuple);

    /*
     * Our update of the pg_attribute row will force a relcache rebuild, so
     * there's nothing else to do here.
     */
    heap_close(attr_rel, RowExclusiveLock);

    /* Keep lock on attribute's rel until end of xact */
    relation_close(myrel, NoLock);
}

/*
 * heap_drop_with_catalog   - removes specified relation from catalogs
 *
 * Note that this routine is not responsible for dropping objects that are
 * linked to the pg_class entry via dependencies (for example, indexes and
 * constraints).  Those are deleted by the dependency-tracing logic in
 * dependency.c before control gets here.  In general, therefore, this routine
 * should never be called directly; go through performDeletion() instead.
 */
void
heap_drop_with_catalog(Oid relid)
{
    Relation    rel;

    /*
     * Open and lock the relation.
     */
    rel = relation_open(relid, AccessExclusiveLock);

    /*
     * There can no longer be anyone *else* touching the relation, but we
     * might still have open queries or cursors, or pending trigger events, in
     * our own session.
     */
    CheckTableNotInUse(rel, "DROP TABLE");

    /*
     * This effectively deletes all rows in the table, and may be done in a
     * serializable transaction.  In that case we must record a rw-conflict in
     * to this transaction from each transaction holding a predicate lock on
     * the table.
     */
    CheckTableForSerializableConflictIn(rel);

    /*
     * Delete pg_foreign_table tuple first.
     */
    if (rel->rd_rel->relkind == RELKIND_FOREIGN_TABLE)
    {
        Relation    rel;
        HeapTuple   tuple;

        rel = heap_open(ForeignTableRelationId, RowExclusiveLock);

        tuple = SearchSysCache1(FOREIGNTABLEREL, ObjectIdGetDatum(relid));
        if (!HeapTupleIsValid(tuple))
            elog(ERROR, "cache lookup failed for foreign table %u", relid);

        simple_heap_delete(rel, &tuple->t_self);

        ReleaseSysCache(tuple);
        heap_close(rel, RowExclusiveLock);
    }

    /*
     * Schedule unlinking of the relation's physical files at commit.
     */
    if (rel->rd_rel->relkind != RELKIND_VIEW &&
        rel->rd_rel->relkind != RELKIND_COMPOSITE_TYPE &&
        rel->rd_rel->relkind != RELKIND_FOREIGN_TABLE)
    {
        RelationDropStorage(rel);
    }

    /*
     * Close relcache entry, but *keep* AccessExclusiveLock on the relation
     * until transaction commit.  This ensures no one else will try to do
     * something with the doomed relation.
     */
    relation_close(rel, NoLock);

    /*
     * Forget any ON COMMIT action for the rel
     */
    remove_on_commit_action(relid);

    /*
     * Flush the relation from the relcache.  We want to do this before
     * starting to remove catalog entries, just to be certain that no relcache
     * entry rebuild will happen partway through.  (That should not really
     * matter, since we don't do CommandCounterIncrement here, but let's be
     * safe.)
     */
    RelationForgetRelation(relid);

    /*
     * remove inheritance information
     */
    RelationRemoveInheritance(relid);

    /*
     * delete statistics
     */
    RemoveStatistics(relid, 0);

    /*
     * delete attribute tuples
     */
    DeleteAttributeTuples(relid);

    /*
     * delete relation tuple
     */
    DeleteRelationTuple(relid);
}


/*
 * Store a default expression for column attnum of relation rel.
 */
void
StoreAttrDefault(Relation rel, AttrNumber attnum,
                 Node *expr, bool is_internal)
{
    char       *adbin;
    char       *adsrc;
    Relation    adrel;
    HeapTuple   tuple;
    Datum       values[4];
    static bool nulls[4] = {false, false, false, false};
    Relation    attrrel;
    HeapTuple   atttup;
    Form_pg_attribute attStruct;
    Oid         attrdefOid;
    ObjectAddress colobject,
                defobject;

    /*
     * Flatten expression to string form for storage.
     */
    adbin = nodeToString(expr);

    /*
     * Also deparse it to form the mostly-obsolete adsrc field.
     */
    adsrc = deparse_expression(expr,
                            deparse_context_for(RelationGetRelationName(rel),
                                                RelationGetRelid(rel)),
                               false, false);

    /*
     * Make the pg_attrdef entry.
     */
    values[Anum_pg_attrdef_adrelid - 1] = RelationGetRelid(rel);
    values[Anum_pg_attrdef_adnum - 1] = attnum;
    values[Anum_pg_attrdef_adbin - 1] = CStringGetTextDatum(adbin);
    values[Anum_pg_attrdef_adsrc - 1] = CStringGetTextDatum(adsrc);

    adrel = heap_open(AttrDefaultRelationId, RowExclusiveLock);

    tuple = heap_form_tuple(adrel->rd_att, values, nulls);
    attrdefOid = simple_heap_insert(adrel, tuple);

    CatalogUpdateIndexes(adrel, tuple);

    defobject.classId = AttrDefaultRelationId;
    defobject.objectId = attrdefOid;
    defobject.objectSubId = 0;

    heap_close(adrel, RowExclusiveLock);

    /* now can free some of the stuff allocated above */
    pfree(DatumGetPointer(values[Anum_pg_attrdef_adbin - 1]));
    pfree(DatumGetPointer(values[Anum_pg_attrdef_adsrc - 1]));
    heap_freetuple(tuple);
    pfree(adbin);
    pfree(adsrc);

    /*
     * Update the pg_attribute entry for the column to show that a default
     * exists.
     */
    attrrel = heap_open(AttributeRelationId, RowExclusiveLock);
    atttup = SearchSysCacheCopy2(ATTNUM,
                                 ObjectIdGetDatum(RelationGetRelid(rel)),
                                 Int16GetDatum(attnum));
    if (!HeapTupleIsValid(atttup))
        elog(ERROR, "cache lookup failed for attribute %d of relation %u",
             attnum, RelationGetRelid(rel));
    attStruct = (Form_pg_attribute) GETSTRUCT(atttup);
    if (!attStruct->atthasdef)
    {
        attStruct->atthasdef = true;
        simple_heap_update(attrrel, &atttup->t_self, atttup);
        /* keep catalog indexes current */
        CatalogUpdateIndexes(attrrel, atttup);
    }
    heap_close(attrrel, RowExclusiveLock);
    heap_freetuple(atttup);

    /*
     * Make a dependency so that the pg_attrdef entry goes away if the column
     * (or whole table) is deleted.
     */
    colobject.classId = RelationRelationId;
    colobject.objectId = RelationGetRelid(rel);
    colobject.objectSubId = attnum;

    recordDependencyOn(&defobject, &colobject, DEPENDENCY_AUTO);

    /*
     * Record dependencies on objects used in the expression, too.
     */
    recordDependencyOnExpr(&defobject, expr, NIL, DEPENDENCY_NORMAL);

    /*
     * Post creation hook for attribute defaults.
     *
     * XXX. ALTER TABLE ALTER COLUMN SET/DROP DEFAULT is implemented
     * with a couple of deletion/creation of the attribute's default entry,
     * so the callee should check existence of an older version of this
     * entry if it needs to distinguish.
     */
    InvokeObjectPostCreateHookArg(AttrDefaultRelationId,
                                  RelationGetRelid(rel), attnum, is_internal);
}

/*
 * Store a check-constraint expression for the given relation.
 *
 * Caller is responsible for updating the count of constraints
 * in the pg_class entry for the relation.
 */
static void
StoreRelCheck(Relation rel, char *ccname, Node *expr,
              bool is_validated, bool is_local, int inhcount,
              bool is_no_inherit, bool is_internal)
{
    char       *ccbin;
    char       *ccsrc;
    List       *varList;
    int         keycount;
    int16      *attNos;

    /*
     * Flatten expression to string form for storage.
     */
    ccbin = nodeToString(expr);

    /*
     * Also deparse it to form the mostly-obsolete consrc field.
     */
    ccsrc = deparse_expression(expr,
                            deparse_context_for(RelationGetRelationName(rel),
                                                RelationGetRelid(rel)),
                               false, false);

    /*
     * Find columns of rel that are used in expr
     *
     * NB: pull_var_clause is okay here only because we don't allow subselects
     * in check constraints; it would fail to examine the contents of
     * subselects.
     */
    varList = pull_var_clause(expr,
                              PVC_REJECT_AGGREGATES,
                              PVC_REJECT_PLACEHOLDERS);
    keycount = list_length(varList);

    if (keycount > 0)
    {
        ListCell   *vl;
        int         i = 0;

        attNos = (int16 *) palloc(keycount * sizeof(int16));
        foreach(vl, varList)
        {
            Var        *var = (Var *) lfirst(vl);
            int         j;

            for (j = 0; j < i; j++)
                if (attNos[j] == var->varattno)
                    break;
            if (j == i)
                attNos[i++] = var->varattno;
        }
        keycount = i;
    }
    else
        attNos = NULL;

    /*
     * Create the Check Constraint
     */
    CreateConstraintEntry(ccname,       /* Constraint Name */
                          RelationGetNamespace(rel),    /* namespace */
                          CONSTRAINT_CHECK,     /* Constraint Type */
                          false,    /* Is Deferrable */
                          false,    /* Is Deferred */
                          is_validated,
                          RelationGetRelid(rel),        /* relation */
                          attNos,       /* attrs in the constraint */
                          keycount,     /* # attrs in the constraint */
                          InvalidOid,   /* not a domain constraint */
                          InvalidOid,   /* no associated index */
                          InvalidOid,   /* Foreign key fields */
                          NULL,
                          NULL,
                          NULL,
                          NULL,
                          0,
                          ' ',
                          ' ',
                          ' ',
                          NULL, /* not an exclusion constraint */
                          expr, /* Tree form of check constraint */
                          ccbin,    /* Binary form of check constraint */
                          ccsrc,    /* Source form of check constraint */
                          is_local,     /* conislocal */
                          inhcount,     /* coninhcount */
                          is_no_inherit,        /* connoinherit */
                          is_internal); /* internally constructed? */

    pfree(ccbin);
    pfree(ccsrc);
}

/*
 * Store defaults and constraints (passed as a list of CookedConstraint).
 *
 * NOTE: only pre-cooked expressions will be passed this way, which is to
 * say expressions inherited from an existing relation.  Newly parsed
 * expressions can be added later, by direct calls to StoreAttrDefault
 * and StoreRelCheck (see AddRelationNewConstraints()).
 */
static void
StoreConstraints(Relation rel, List *cooked_constraints, bool is_internal)
{
    int         numchecks = 0;
    ListCell   *lc;

    if (!cooked_constraints)
        return;                 /* nothing to do */

    /*
     * Deparsing of constraint expressions will fail unless the just-created
     * pg_attribute tuples for this relation are made visible.  So, bump the
     * command counter.  CAUTION: this will cause a relcache entry rebuild.
     */
    CommandCounterIncrement();

    foreach(lc, cooked_constraints)
    {
        CookedConstraint *con = (CookedConstraint *) lfirst(lc);

        switch (con->contype)
        {
            case CONSTR_DEFAULT:
                StoreAttrDefault(rel, con->attnum, con->expr, is_internal);
                break;
            case CONSTR_CHECK:
                StoreRelCheck(rel, con->name, con->expr, !con->skip_validation,
                              con->is_local, con->inhcount,
                              con->is_no_inherit, is_internal);
                numchecks++;
                break;
            default:
                elog(ERROR, "unrecognized constraint type: %d",
                     (int) con->contype);
        }
    }

    if (numchecks > 0)
        SetRelationNumChecks(rel, numchecks);
}

/*
 * AddRelationNewConstraints
 *
 * Add new column default expressions and/or constraint check expressions
 * to an existing relation.  This is defined to do both for efficiency in
 * DefineRelation, but of course you can do just one or the other by passing
 * empty lists.
 *
 * rel: relation to be modified
 * newColDefaults: list of RawColumnDefault structures
 * newConstraints: list of Constraint nodes
 * allow_merge: TRUE if check constraints may be merged with existing ones
 * is_local: TRUE if definition is local, FALSE if it's inherited
 * is_internal: TRUE if result of some internal process, not a user request
 *
 * All entries in newColDefaults will be processed.  Entries in newConstraints
 * will be processed only if they are CONSTR_CHECK type.
 *
 * Returns a list of CookedConstraint nodes that shows the cooked form of
 * the default and constraint expressions added to the relation.
 *
 * NB: caller should have opened rel with AccessExclusiveLock, and should
 * hold that lock till end of transaction.  Also, we assume the caller has
 * done a CommandCounterIncrement if necessary to make the relation's catalog
 * tuples visible.
 */
List *
AddRelationNewConstraints(Relation rel,
                          List *newColDefaults,
                          List *newConstraints,
                          bool allow_merge,
                          bool is_local,
                          bool is_internal)
{
    List       *cookedConstraints = NIL;
    TupleDesc   tupleDesc;
    TupleConstr *oldconstr;
    int         numoldchecks;
    ParseState *pstate;
    RangeTblEntry *rte;
    int         numchecks;
    List       *checknames;
    ListCell   *cell;
    Node       *expr;
    CookedConstraint *cooked;

    /*
     * Get info about existing constraints.
     */
    tupleDesc = RelationGetDescr(rel);
    oldconstr = tupleDesc->constr;
    if (oldconstr)
        numoldchecks = oldconstr->num_check;
    else
        numoldchecks = 0;

    /*
     * Create a dummy ParseState and insert the target relation as its sole
     * rangetable entry.  We need a ParseState for transformExpr.
     */
    pstate = make_parsestate(NULL);
    rte = addRangeTableEntryForRelation(pstate,
                                        rel,
                                        NULL,
                                        false,
                                        true);
    addRTEtoQuery(pstate, rte, true, true, true);

    /*
     * Process column default expressions.
     */
    foreach(cell, newColDefaults)
    {
        RawColumnDefault *colDef = (RawColumnDefault *) lfirst(cell);
        Form_pg_attribute atp = rel->rd_att->attrs[colDef->attnum - 1];

        expr = cookDefault(pstate, colDef->raw_default,
                           atp->atttypid, atp->atttypmod,
                           NameStr(atp->attname));

        /*
         * If the expression is just a NULL constant, we do not bother to make
         * an explicit pg_attrdef entry, since the default behavior is
         * equivalent.
         *
         * Note a nonobvious property of this test: if the column is of a
         * domain type, what we'll get is not a bare null Const but a
         * CoerceToDomain expr, so we will not discard the default.  This is
         * critical because the column default needs to be retained to
         * override any default that the domain might have.
         */
        if (expr == NULL ||
            (IsA(expr, Const) &&((Const *) expr)->constisnull))
            continue;

        StoreAttrDefault(rel, colDef->attnum, expr, is_internal);

        cooked = (CookedConstraint *) palloc(sizeof(CookedConstraint));
        cooked->contype = CONSTR_DEFAULT;
        cooked->name = NULL;
        cooked->attnum = colDef->attnum;
        cooked->expr = expr;
        cooked->skip_validation = false;
        cooked->is_local = is_local;
        cooked->inhcount = is_local ? 0 : 1;
        cooked->is_no_inherit = false;
        cookedConstraints = lappend(cookedConstraints, cooked);
    }

    /*
     * Process constraint expressions.
     */
    numchecks = numoldchecks;
    checknames = NIL;
    foreach(cell, newConstraints)
    {
        Constraint *cdef = (Constraint *) lfirst(cell);
        char       *ccname;

        if (cdef->contype != CONSTR_CHECK)
            continue;

        if (cdef->raw_expr != NULL)
        {
            Assert(cdef->cooked_expr == NULL);

            /*
             * Transform raw parsetree to executable expression, and verify
             * it's valid as a CHECK constraint.
             */
            expr = cookConstraint(pstate, cdef->raw_expr,
                                  RelationGetRelationName(rel));
        }
        else
        {
            Assert(cdef->cooked_expr != NULL);

            /*
             * Here, we assume the parser will only pass us valid CHECK
             * expressions, so we do no particular checking.
             */
            expr = stringToNode(cdef->cooked_expr);
        }

        /*
         * Check name uniqueness, or generate a name if none was given.
         */
        if (cdef->conname != NULL)
        {
            ListCell   *cell2;

            ccname = cdef->conname;
            /* Check against other new constraints */
            /* Needed because we don't do CommandCounterIncrement in loop */
            foreach(cell2, checknames)
            {
                if (strcmp((char *) lfirst(cell2), ccname) == 0)
                    ereport(ERROR,
                            (errcode(ERRCODE_DUPLICATE_OBJECT),
                             errmsg("check constraint \"%s\" already exists",
                                    ccname)));
            }

            /* save name for future checks */
            checknames = lappend(checknames, ccname);

            /*
             * Check against pre-existing constraints.  If we are allowed to
             * merge with an existing constraint, there's no more to do here.
             * (We omit the duplicate constraint from the result, which is
             * what ATAddCheckConstraint wants.)
             */
            if (MergeWithExistingConstraint(rel, ccname, expr,
                                            allow_merge, is_local,
                                            cdef->is_no_inherit))
                continue;
        }
        else
        {
            /*
             * When generating a name, we want to create "tab_col_check" for a
             * column constraint and "tab_check" for a table constraint.  We
             * no longer have any info about the syntactic positioning of the
             * constraint phrase, so we approximate this by seeing whether the
             * expression references more than one column.  (If the user
             * played by the rules, the result is the same...)
             *
             * Note: pull_var_clause() doesn't descend into sublinks, but we
             * eliminated those above; and anyway this only needs to be an
             * approximate answer.
             */
            List       *vars;
            char       *colname;

            vars = pull_var_clause(expr,
                                   PVC_REJECT_AGGREGATES,
                                   PVC_REJECT_PLACEHOLDERS);

            /* eliminate duplicates */
            vars = list_union(NIL, vars);

            if (list_length(vars) == 1)
                colname = get_attname(RelationGetRelid(rel),
                                      ((Var *) linitial(vars))->varattno);
            else
                colname = NULL;

            ccname = ChooseConstraintName(RelationGetRelationName(rel),
                                          colname,
                                          "check",
                                          RelationGetNamespace(rel),
                                          checknames);

            /* save name for future checks */
            checknames = lappend(checknames, ccname);
        }

        /*
         * OK, store it.
         */
        StoreRelCheck(rel, ccname, expr, !cdef->skip_validation, is_local,
                      is_local ? 0 : 1, cdef->is_no_inherit, is_internal);

        numchecks++;

        cooked = (CookedConstraint *) palloc(sizeof(CookedConstraint));
        cooked->contype = CONSTR_CHECK;
        cooked->name = ccname;
        cooked->attnum = 0;
        cooked->expr = expr;
        cooked->skip_validation = cdef->skip_validation;
        cooked->is_local = is_local;
        cooked->inhcount = is_local ? 0 : 1;
        cooked->is_no_inherit = cdef->is_no_inherit;
        cookedConstraints = lappend(cookedConstraints, cooked);
    }

    /*
     * Update the count of constraints in the relation's pg_class tuple. We do
     * this even if there was no change, in order to ensure that an SI update
     * message is sent out for the pg_class tuple, which will force other
     * backends to rebuild their relcache entries for the rel. (This is
     * critical if we added defaults but not constraints.)
     */
    SetRelationNumChecks(rel, numchecks);

    return cookedConstraints;
}

/*
 * Check for a pre-existing check constraint that conflicts with a proposed
 * new one, and either adjust its conislocal/coninhcount settings or throw
 * error as needed.
 *
 * Returns TRUE if merged (constraint is a duplicate), or FALSE if it's
 * got a so-far-unique name, or throws error if conflict.
 *
 * XXX See MergeConstraintsIntoExisting too if you change this code.
 */
static bool
MergeWithExistingConstraint(Relation rel, char *ccname, Node *expr,
                            bool allow_merge, bool is_local,
                            bool is_no_inherit)
{
    bool        found;
    Relation    conDesc;
    SysScanDesc conscan;
    ScanKeyData skey[2];
    HeapTuple   tup;

    /* Search for a pg_constraint entry with same name and relation */
    conDesc = heap_open(ConstraintRelationId, RowExclusiveLock);

    found = false;

    ScanKeyInit(&skey[0],
                Anum_pg_constraint_conname,
                BTEqualStrategyNumber, F_NAMEEQ,
                CStringGetDatum(ccname));

    ScanKeyInit(&skey[1],
                Anum_pg_constraint_connamespace,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(RelationGetNamespace(rel)));

    conscan = systable_beginscan(conDesc, ConstraintNameNspIndexId, true,
                                 SnapshotNow, 2, skey);

    while (HeapTupleIsValid(tup = systable_getnext(conscan)))
    {
        Form_pg_constraint con = (Form_pg_constraint) GETSTRUCT(tup);

        if (con->conrelid == RelationGetRelid(rel))
        {
            /* Found it.  Conflicts if not identical check constraint */
            if (con->contype == CONSTRAINT_CHECK)
            {
                Datum       val;
                bool        isnull;

                val = fastgetattr(tup,
                                  Anum_pg_constraint_conbin,
                                  conDesc->rd_att, &isnull);
                if (isnull)
                    elog(ERROR, "null conbin for rel %s",
                         RelationGetRelationName(rel));
                if (equal(expr, stringToNode(TextDatumGetCString(val))))
                    found = true;
            }
            if (!found || !allow_merge)
                ereport(ERROR,
                        (errcode(ERRCODE_DUPLICATE_OBJECT),
                errmsg("constraint \"%s\" for relation \"%s\" already exists",
                       ccname, RelationGetRelationName(rel))));

            tup = heap_copytuple(tup);
            con = (Form_pg_constraint) GETSTRUCT(tup);

            /* If the constraint is "no inherit" then cannot merge */
            if (con->connoinherit)
                ereport(ERROR,
                        (errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
                         errmsg("constraint \"%s\" conflicts with non-inherited constraint on relation \"%s\"",
                                ccname, RelationGetRelationName(rel))));

            if (is_local)
                con->conislocal = true;
            else
                con->coninhcount++;
            if (is_no_inherit)
            {
                Assert(is_local);
                con->connoinherit = true;
            }
            /* OK to update the tuple */
            ereport(NOTICE,
               (errmsg("merging constraint \"%s\" with inherited definition",
                       ccname)));
            simple_heap_update(conDesc, &tup->t_self, tup);
            CatalogUpdateIndexes(conDesc, tup);
            break;
        }
    }

    systable_endscan(conscan);
    heap_close(conDesc, RowExclusiveLock);

    return found;
}

/*
 * Update the count of constraints in the relation's pg_class tuple.
 *
 * Caller had better hold exclusive lock on the relation.
 *
 * An important side effect is that a SI update message will be sent out for
 * the pg_class tuple, which will force other backends to rebuild their
 * relcache entries for the rel.  Also, this backend will rebuild its
 * own relcache entry at the next CommandCounterIncrement.
 */
static void
SetRelationNumChecks(Relation rel, int numchecks)
{
    Relation    relrel;
    HeapTuple   reltup;
    Form_pg_class relStruct;

    relrel = heap_open(RelationRelationId, RowExclusiveLock);
    reltup = SearchSysCacheCopy1(RELOID,
                                 ObjectIdGetDatum(RelationGetRelid(rel)));
    if (!HeapTupleIsValid(reltup))
        elog(ERROR, "cache lookup failed for relation %u",
             RelationGetRelid(rel));
    relStruct = (Form_pg_class) GETSTRUCT(reltup);

    if (relStruct->relchecks != numchecks)
    {
        relStruct->relchecks = numchecks;

        simple_heap_update(relrel, &reltup->t_self, reltup);

        /* keep catalog indexes current */
        CatalogUpdateIndexes(relrel, reltup);
    }
    else
    {
        /* Skip the disk update, but force relcache inval anyway */
        CacheInvalidateRelcache(rel);
    }

    heap_freetuple(reltup);
    heap_close(relrel, RowExclusiveLock);
}

/*
 * Take a raw default and convert it to a cooked format ready for
 * storage.
 *
 * Parse state should be set up to recognize any vars that might appear
 * in the expression.  (Even though we plan to reject vars, it's more
 * user-friendly to give the correct error message than "unknown var".)
 *
 * If atttypid is not InvalidOid, coerce the expression to the specified
 * type (and typmod atttypmod).   attname is only needed in this case:
 * it is used in the error message, if any.
 */
Node *
cookDefault(ParseState *pstate,
            Node *raw_default,
            Oid atttypid,
            int32 atttypmod,
            char *attname)
{
    Node       *expr;

    Assert(raw_default != NULL);

    /*
     * Transform raw parsetree to executable expression.
     */
    expr = transformExpr(pstate, raw_default, EXPR_KIND_COLUMN_DEFAULT);

    /*
     * Make sure default expr does not refer to any vars (we need this check
     * since the pstate includes the target table).
     */
    if (contain_var_clause(expr))
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
              errmsg("cannot use column references in default expression")));

    /*
     * transformExpr() should have already rejected subqueries, aggregates,
     * and window functions, based on the EXPR_KIND_ for a default expression.
     *
     * It can't return a set either.
     */
    if (expression_returns_set(expr))
        ereport(ERROR,
                (errcode(ERRCODE_DATATYPE_MISMATCH),
                 errmsg("default expression must not return a set")));

    /*
     * Coerce the expression to the correct type and typmod, if given. This
     * should match the parser's processing of non-defaulted expressions ---
     * see transformAssignedExpr().
     */
    if (OidIsValid(atttypid))
    {
        Oid         type_id = exprType(expr);

        expr = coerce_to_target_type(pstate, expr, type_id,
                                     atttypid, atttypmod,
                                     COERCION_ASSIGNMENT,
                                     COERCE_IMPLICIT_CAST,
                                     -1);
        if (expr == NULL)
            ereport(ERROR,
                    (errcode(ERRCODE_DATATYPE_MISMATCH),
                     errmsg("column \"%s\" is of type %s"
                            " but default expression is of type %s",
                            attname,
                            format_type_be(atttypid),
                            format_type_be(type_id)),
               errhint("You will need to rewrite or cast the expression.")));
    }

    /*
     * Finally, take care of collations in the finished expression.
     */
    assign_expr_collations(pstate, expr);

    return expr;
}

/*
 * Take a raw CHECK constraint expression and convert it to a cooked format
 * ready for storage.
 *
 * Parse state must be set up to recognize any vars that might appear
 * in the expression.
 */
static Node *
cookConstraint(ParseState *pstate,
               Node *raw_constraint,
               char *relname)
{
    Node       *expr;

    /*
     * Transform raw parsetree to executable expression.
     */
    expr = transformExpr(pstate, raw_constraint, EXPR_KIND_CHECK_CONSTRAINT);

    /*
     * Make sure it yields a boolean result.
     */
    expr = coerce_to_boolean(pstate, expr, "CHECK");

    /*
     * Take care of collations.
     */
    assign_expr_collations(pstate, expr);

    /*
     * Make sure no outside relations are referred to (this is probably dead
     * code now that add_missing_from is history).
     */
    if (list_length(pstate->p_rtable) != 1)
        ereport(ERROR,
                (errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
            errmsg("only table \"%s\" can be referenced in check constraint",
                   relname)));

    return expr;
}


/*
 * RemoveStatistics --- remove entries in pg_statistic for a rel or column
 *
 * If attnum is zero, remove all entries for rel; else remove only the one(s)
 * for that column.
 */
void
RemoveStatistics(Oid relid, AttrNumber attnum)
{
    Relation    pgstatistic;
    SysScanDesc scan;
    ScanKeyData key[2];
    int         nkeys;
    HeapTuple   tuple;

    pgstatistic = heap_open(StatisticRelationId, RowExclusiveLock);

    ScanKeyInit(&key[0],
                Anum_pg_statistic_starelid,
                BTEqualStrategyNumber, F_OIDEQ,
                ObjectIdGetDatum(relid));

    if (attnum == 0)
        nkeys = 1;
    else
    {
        ScanKeyInit(&key[1],
                    Anum_pg_statistic_staattnum,
                    BTEqualStrategyNumber, F_INT2EQ,
                    Int16GetDatum(attnum));
        nkeys = 2;
    }

    scan = systable_beginscan(pgstatistic, StatisticRelidAttnumInhIndexId, true,
                              SnapshotNow, nkeys, key);

    /* we must loop even when attnum != 0, in case of inherited stats */
    while (HeapTupleIsValid(tuple = systable_getnext(scan)))
        simple_heap_delete(pgstatistic, &tuple->t_self);

    systable_endscan(scan);

    heap_close(pgstatistic, RowExclusiveLock);
}


/*
 * RelationTruncateIndexes - truncate all indexes associated
 * with the heap relation to zero tuples.
 *
 * The routine will truncate and then reconstruct the indexes on
 * the specified relation.  Caller must hold exclusive lock on rel.
 */
static void
RelationTruncateIndexes(Relation heapRelation)
{
    ListCell   *indlist;

    /* Ask the relcache to produce a list of the indexes of the rel */
    foreach(indlist, RelationGetIndexList(heapRelation))
    {
        Oid         indexId = lfirst_oid(indlist);
        Relation    currentIndex;
        IndexInfo  *indexInfo;

        /* Open the index relation; use exclusive lock, just to be sure */
        currentIndex = index_open(indexId, AccessExclusiveLock);

        /* Fetch info needed for index_build */
        indexInfo = BuildIndexInfo(currentIndex);

        /*
         * Now truncate the actual file (and discard buffers).
         */
        RelationTruncate(currentIndex, 0);

        /* Initialize the index and rebuild */
        /* Note: we do not need to re-establish pkey setting */
        index_build(heapRelation, currentIndex, indexInfo, false, true);

        /* We're done with this index */
        index_close(currentIndex, NoLock);
    }
}

/*
 *   heap_truncate
 *
 *   This routine deletes all data within all the specified relations.
 *
 * This is not transaction-safe!  There is another, transaction-safe
 * implementation in commands/tablecmds.c.  We now use this only for
 * ON COMMIT truncation of temporary tables, where it doesn't matter.
 */
void
heap_truncate(List *relids)
{
    List       *relations = NIL;
    ListCell   *cell;

    /* Open relations for processing, and grab exclusive access on each */
    foreach(cell, relids)
    {
        Oid         rid = lfirst_oid(cell);
        Relation    rel;

        rel = heap_open(rid, AccessExclusiveLock);
        relations = lappend(relations, rel);
    }

    /* Don't allow truncate on tables that are referenced by foreign keys */
    heap_truncate_check_FKs(relations, true);

    /* OK to do it */
    foreach(cell, relations)
    {
        Relation    rel = lfirst(cell);

        /* Truncate the relation */
        heap_truncate_one_rel(rel);

        /* Close the relation, but keep exclusive lock on it until commit */
        heap_close(rel, NoLock);
    }
}

/*
 *   heap_truncate_one_rel
 *
 *   This routine deletes all data within the specified relation.
 *
 * This is not transaction-safe, because the truncation is done immediately
 * and cannot be rolled back later.  Caller is responsible for having
 * checked permissions etc, and must have obtained AccessExclusiveLock.
 */
void
heap_truncate_one_rel(Relation rel)
{
    Oid         toastrelid;

    /* Truncate the actual file (and discard buffers) */
    RelationTruncate(rel, 0);

    /* If the relation has indexes, truncate the indexes too */
    RelationTruncateIndexes(rel);

    /* If there is a toast table, truncate that too */
    toastrelid = rel->rd_rel->reltoastrelid;
    if (OidIsValid(toastrelid))
    {
        Relation    toastrel = heap_open(toastrelid, AccessExclusiveLock);

        RelationTruncate(toastrel, 0);
        RelationTruncateIndexes(toastrel);
        /* keep the lock... */
        heap_close(toastrel, NoLock);
    }
}

/*
 * heap_truncate_check_FKs
 *      Check for foreign keys referencing a list of relations that
 *      are to be truncated, and raise error if there are any
 *
 * We disallow such FKs (except self-referential ones) since the whole point
 * of TRUNCATE is to not scan the individual rows to be thrown away.
 *
 * This is split out so it can be shared by both implementations of truncate.
 * Caller should already hold a suitable lock on the relations.
 *
 * tempTables is only used to select an appropriate error message.
 */
void
heap_truncate_check_FKs(List *relations, bool tempTables)
{
    List       *oids = NIL;
    List       *dependents;
    ListCell   *cell;

    /*
     * Build a list of OIDs of the interesting relations.
     *
     * If a relation has no triggers, then it can neither have FKs nor be
     * referenced by a FK from another table, so we can ignore it.
     */
    foreach(cell, relations)
    {
        Relation    rel = lfirst(cell);

        if (rel->rd_rel->relhastriggers)
            oids = lappend_oid(oids, RelationGetRelid(rel));
    }

    /*
     * Fast path: if no relation has triggers, none has FKs either.
     */
    if (oids == NIL)
        return;

    /*
     * Otherwise, must scan pg_constraint.  We make one pass with all the
     * relations considered; if this finds nothing, then all is well.
     */
    dependents = heap_truncate_find_FKs(oids);
    if (dependents == NIL)
        return;

    /*
     * Otherwise we repeat the scan once per relation to identify a particular
     * pair of relations to complain about.  This is pretty slow, but
     * performance shouldn't matter much in a failure path.  The reason for
     * doing things this way is to ensure that the message produced is not
     * dependent on chance row locations within pg_constraint.
     */
    foreach(cell, oids)
    {
        Oid         relid = lfirst_oid(cell);
        ListCell   *cell2;

        dependents = heap_truncate_find_FKs(list_make1_oid(relid));

        foreach(cell2, dependents)
        {
            Oid         relid2 = lfirst_oid(cell2);

            if (!list_member_oid(oids, relid2))
            {
                char       *relname = get_rel_name(relid);
                char       *relname2 = get_rel_name(relid2);

                if (tempTables)
                    ereport(ERROR,
                            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                             errmsg("unsupported ON COMMIT and foreign key combination"),
                             errdetail("Table \"%s\" references \"%s\", but they do not have the same ON COMMIT setting.",
                                       relname2, relname)));
                else
                    ereport(ERROR,
                            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                             errmsg("cannot truncate a table referenced in a foreign key constraint"),
                             errdetail("Table \"%s\" references \"%s\".",
                                       relname2, relname),
                           errhint("Truncate table \"%s\" at the same time, "
                                   "or use TRUNCATE ... CASCADE.",
                                   relname2)));
            }
        }
    }
}

/*
 * heap_truncate_find_FKs
 *      Find relations having foreign keys referencing any of the given rels
 *
 * Input and result are both lists of relation OIDs.  The result contains
 * no duplicates, does *not* include any rels that were already in the input
 * list, and is sorted in OID order.  (The last property is enforced mainly
 * to guarantee consistent behavior in the regression tests; we don't want
 * behavior to change depending on chance locations of rows in pg_constraint.)
 *
 * Note: caller should already have appropriate lock on all rels mentioned
 * in relationIds.  Since adding or dropping an FK requires exclusive lock
 * on both rels, this ensures that the answer will be stable.
 */
List *
heap_truncate_find_FKs(List *relationIds)
{
    List       *result = NIL;
    Relation    fkeyRel;
    SysScanDesc fkeyScan;
    HeapTuple   tuple;

    /*
     * Must scan pg_constraint.  Right now, it is a seqscan because there is
     * no available index on confrelid.
     */
    fkeyRel = heap_open(ConstraintRelationId, AccessShareLock);

    fkeyScan = systable_beginscan(fkeyRel, InvalidOid, false,
                                  SnapshotNow, 0, NULL);

    while (HeapTupleIsValid(tuple = systable_getnext(fkeyScan)))
    {
        Form_pg_constraint con = (Form_pg_constraint) GETSTRUCT(tuple);

        /* Not a foreign key */
        if (con->contype != CONSTRAINT_FOREIGN)
            continue;

        /* Not referencing one of our list of tables */
        if (!list_member_oid(relationIds, con->confrelid))
            continue;

        /* Add referencer unless already in input or result list */
        if (!list_member_oid(relationIds, con->conrelid))
            result = insert_ordered_unique_oid(result, con->conrelid);
    }

    systable_endscan(fkeyScan);
    heap_close(fkeyRel, AccessShareLock);

    return result;
}

/*
 * insert_ordered_unique_oid
 *      Insert a new Oid into a sorted list of Oids, preserving ordering,
 *      and eliminating duplicates
 *
 * Building the ordered list this way is O(N^2), but with a pretty small
 * constant, so for the number of entries we expect it will probably be
 * faster than trying to apply qsort().  It seems unlikely someone would be
 * trying to truncate a table with thousands of dependent tables ...
 */
static List *
insert_ordered_unique_oid(List *list, Oid datum)
{
    ListCell   *prev;

    /* Does the datum belong at the front? */
    if (list == NIL || datum < linitial_oid(list))
        return lcons_oid(datum, list);
    /* Does it match the first entry? */
    if (datum == linitial_oid(list))
        return list;            /* duplicate, so don't insert */
    /* No, so find the entry it belongs after */
    prev = list_head(list);
    for (;;)
    {
        ListCell   *curr = lnext(prev);

        if (curr == NULL || datum < lfirst_oid(curr))
            break;              /* it belongs after 'prev', before 'curr' */

        if (datum == lfirst_oid(curr))
            return list;        /* duplicate, so don't insert */

        prev = curr;
    }
    /* Insert datum into list after 'prev' */
    lappend_cell_oid(list, prev, datum);
    return list;
}