tupdesc.c

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/*-------------------------------------------------------------------------
 *
 * tupdesc.c
 *    POSTGRES tuple descriptor support code
 *
 * Portions Copyright (c) 1996-2013, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    src/backend/access/common/tupdesc.c
 *
 * NOTES
 *    some of the executor utility code such as "ExecTypeFromTL" should be
 *    moved here.
 *
 *-------------------------------------------------------------------------
 */

#include "postgres.h"

#include "access/htup_details.h"
#include "catalog/pg_type.h"
#include "miscadmin.h"
#include "parser/parse_type.h"
#include "utils/acl.h"
#include "utils/builtins.h"
#include "utils/resowner_private.h"
#include "utils/syscache.h"


/*
 * CreateTemplateTupleDesc
 *      This function allocates an empty tuple descriptor structure.
 *
 * Tuple type ID information is initially set for an anonymous record type;
 * caller can overwrite this if needed.
 */
TupleDesc
CreateTemplateTupleDesc(int natts, bool hasoid)
{
    TupleDesc   desc;
    char       *stg;
    int         attroffset;

    /*
     * sanity checks
     */
    AssertArg(natts >= 0);

    /*
     * Allocate enough memory for the tuple descriptor, including the
     * attribute rows, and set up the attribute row pointers.
     *
     * Note: we assume that sizeof(struct tupleDesc) is a multiple of the
     * struct pointer alignment requirement, and hence we don't need to insert
     * alignment padding between the struct and the array of attribute row
     * pointers.
     *
     * Note: Only the fixed part of pg_attribute rows is included in tuple
     * descriptors, so we only need ATTRIBUTE_FIXED_PART_SIZE space per attr.
     * That might need alignment padding, however.
     */
    attroffset = sizeof(struct tupleDesc) + natts * sizeof(Form_pg_attribute);
    attroffset = MAXALIGN(attroffset);
    stg = palloc(attroffset + natts * MAXALIGN(ATTRIBUTE_FIXED_PART_SIZE));
    desc = (TupleDesc) stg;

    if (natts > 0)
    {
        Form_pg_attribute *attrs;
        int         i;

        attrs = (Form_pg_attribute *) (stg + sizeof(struct tupleDesc));
        desc->attrs = attrs;
        stg += attroffset;
        for (i = 0; i < natts; i++)
        {
            attrs[i] = (Form_pg_attribute) stg;
            stg += MAXALIGN(ATTRIBUTE_FIXED_PART_SIZE);
        }
    }
    else
        desc->attrs = NULL;

    /*
     * Initialize other fields of the tupdesc.
     */
    desc->natts = natts;
    desc->constr = NULL;
    desc->tdtypeid = RECORDOID;
    desc->tdtypmod = -1;
    desc->tdhasoid = hasoid;
    desc->tdrefcount = -1;      /* assume not reference-counted */

    return desc;
}

/*
 * CreateTupleDesc
 *      This function allocates a new TupleDesc pointing to a given
 *      Form_pg_attribute array.
 *
 * Note: if the TupleDesc is ever freed, the Form_pg_attribute array
 * will not be freed thereby.
 *
 * Tuple type ID information is initially set for an anonymous record type;
 * caller can overwrite this if needed.
 */
TupleDesc
CreateTupleDesc(int natts, bool hasoid, Form_pg_attribute *attrs)
{
    TupleDesc   desc;

    /*
     * sanity checks
     */
    AssertArg(natts >= 0);

    desc = (TupleDesc) palloc(sizeof(struct tupleDesc));
    desc->attrs = attrs;
    desc->natts = natts;
    desc->constr = NULL;
    desc->tdtypeid = RECORDOID;
    desc->tdtypmod = -1;
    desc->tdhasoid = hasoid;
    desc->tdrefcount = -1;      /* assume not reference-counted */

    return desc;
}

/*
 * CreateTupleDescCopy
 *      This function creates a new TupleDesc by copying from an existing
 *      TupleDesc.
 *
 * !!! Constraints and defaults are not copied !!!
 */
TupleDesc
CreateTupleDescCopy(TupleDesc tupdesc)
{
    TupleDesc   desc;
    int         i;

    desc = CreateTemplateTupleDesc(tupdesc->natts, tupdesc->tdhasoid);

    for (i = 0; i < desc->natts; i++)
    {
        memcpy(desc->attrs[i], tupdesc->attrs[i], ATTRIBUTE_FIXED_PART_SIZE);
        desc->attrs[i]->attnotnull = false;
        desc->attrs[i]->atthasdef = false;
    }

    desc->tdtypeid = tupdesc->tdtypeid;
    desc->tdtypmod = tupdesc->tdtypmod;

    return desc;
}

/*
 * CreateTupleDescCopyConstr
 *      This function creates a new TupleDesc by copying from an existing
 *      TupleDesc (including its constraints and defaults).
 */
TupleDesc
CreateTupleDescCopyConstr(TupleDesc tupdesc)
{
    TupleDesc   desc;
    TupleConstr *constr = tupdesc->constr;
    int         i;

    desc = CreateTemplateTupleDesc(tupdesc->natts, tupdesc->tdhasoid);

    for (i = 0; i < desc->natts; i++)
    {
        memcpy(desc->attrs[i], tupdesc->attrs[i], ATTRIBUTE_FIXED_PART_SIZE);
    }

    if (constr)
    {
        TupleConstr *cpy = (TupleConstr *) palloc0(sizeof(TupleConstr));

        cpy->has_not_null = constr->has_not_null;

        if ((cpy->num_defval = constr->num_defval) > 0)
        {
            cpy->defval = (AttrDefault *) palloc(cpy->num_defval * sizeof(AttrDefault));
            memcpy(cpy->defval, constr->defval, cpy->num_defval * sizeof(AttrDefault));
            for (i = cpy->num_defval - 1; i >= 0; i--)
            {
                if (constr->defval[i].adbin)
                    cpy->defval[i].adbin = pstrdup(constr->defval[i].adbin);
            }
        }

        if ((cpy->num_check = constr->num_check) > 0)
        {
            cpy->check = (ConstrCheck *) palloc(cpy->num_check * sizeof(ConstrCheck));
            memcpy(cpy->check, constr->check, cpy->num_check * sizeof(ConstrCheck));
            for (i = cpy->num_check - 1; i >= 0; i--)
            {
                if (constr->check[i].ccname)
                    cpy->check[i].ccname = pstrdup(constr->check[i].ccname);
                if (constr->check[i].ccbin)
                    cpy->check[i].ccbin = pstrdup(constr->check[i].ccbin);
                cpy->check[i].ccvalid = constr->check[i].ccvalid;
            }
        }

        desc->constr = cpy;
    }

    desc->tdtypeid = tupdesc->tdtypeid;
    desc->tdtypmod = tupdesc->tdtypmod;

    return desc;
}

/*
 * Free a TupleDesc including all substructure
 */
void
FreeTupleDesc(TupleDesc tupdesc)
{
    int         i;

    /*
     * Possibly this should assert tdrefcount == 0, to disallow explicit
     * freeing of un-refcounted tupdescs?
     */
    Assert(tupdesc->tdrefcount <= 0);

    if (tupdesc->constr)
    {
        if (tupdesc->constr->num_defval > 0)
        {
            AttrDefault *attrdef = tupdesc->constr->defval;

            for (i = tupdesc->constr->num_defval - 1; i >= 0; i--)
            {
                if (attrdef[i].adbin)
                    pfree(attrdef[i].adbin);
            }
            pfree(attrdef);
        }
        if (tupdesc->constr->num_check > 0)
        {
            ConstrCheck *check = tupdesc->constr->check;

            for (i = tupdesc->constr->num_check - 1; i >= 0; i--)
            {
                if (check[i].ccname)
                    pfree(check[i].ccname);
                if (check[i].ccbin)
                    pfree(check[i].ccbin);
            }
            pfree(check);
        }
        pfree(tupdesc->constr);
    }

    pfree(tupdesc);
}

/*
 * Increment the reference count of a tupdesc, and log the reference in
 * CurrentResourceOwner.
 *
 * Do not apply this to tupdescs that are not being refcounted.  (Use the
 * macro PinTupleDesc for tupdescs of uncertain status.)
 */
void
IncrTupleDescRefCount(TupleDesc tupdesc)
{
    Assert(tupdesc->tdrefcount >= 0);

    ResourceOwnerEnlargeTupleDescs(CurrentResourceOwner);
    tupdesc->tdrefcount++;
    ResourceOwnerRememberTupleDesc(CurrentResourceOwner, tupdesc);
}

/*
 * Decrement the reference count of a tupdesc, remove the corresponding
 * reference from CurrentResourceOwner, and free the tupdesc if no more
 * references remain.
 *
 * Do not apply this to tupdescs that are not being refcounted.  (Use the
 * macro ReleaseTupleDesc for tupdescs of uncertain status.)
 */
void
DecrTupleDescRefCount(TupleDesc tupdesc)
{
    Assert(tupdesc->tdrefcount > 0);

    ResourceOwnerForgetTupleDesc(CurrentResourceOwner, tupdesc);
    if (--tupdesc->tdrefcount == 0)
        FreeTupleDesc(tupdesc);
}

/*
 * Compare two TupleDesc structures for logical equality
 *
 * Note: we deliberately do not check the attrelid and tdtypmod fields.
 * This allows typcache.c to use this routine to see if a cached record type
 * matches a requested type, and is harmless for relcache.c's uses.
 * We don't compare tdrefcount, either.
 */
bool
equalTupleDescs(TupleDesc tupdesc1, TupleDesc tupdesc2)
{
    int         i,
                j,
                n;

    if (tupdesc1->natts != tupdesc2->natts)
        return false;
    if (tupdesc1->tdtypeid != tupdesc2->tdtypeid)
        return false;
    if (tupdesc1->tdhasoid != tupdesc2->tdhasoid)
        return false;

    for (i = 0; i < tupdesc1->natts; i++)
    {
        Form_pg_attribute attr1 = tupdesc1->attrs[i];
        Form_pg_attribute attr2 = tupdesc2->attrs[i];

        /*
         * We do not need to check every single field here: we can disregard
         * attrelid and attnum (which were used to place the row in the attrs
         * array in the first place).  It might look like we could dispense
         * with checking attlen/attbyval/attalign, since these are derived
         * from atttypid; but in the case of dropped columns we must check
         * them (since atttypid will be zero for all dropped columns) and in
         * general it seems safer to check them always.
         *
         * attcacheoff must NOT be checked since it's possibly not set in both
         * copies.
         */
        if (strcmp(NameStr(attr1->attname), NameStr(attr2->attname)) != 0)
            return false;
        if (attr1->atttypid != attr2->atttypid)
            return false;
        if (attr1->attstattarget != attr2->attstattarget)
            return false;
        if (attr1->attlen != attr2->attlen)
            return false;
        if (attr1->attndims != attr2->attndims)
            return false;
        if (attr1->atttypmod != attr2->atttypmod)
            return false;
        if (attr1->attbyval != attr2->attbyval)
            return false;
        if (attr1->attstorage != attr2->attstorage)
            return false;
        if (attr1->attalign != attr2->attalign)
            return false;
        if (attr1->attnotnull != attr2->attnotnull)
            return false;
        if (attr1->atthasdef != attr2->atthasdef)
            return false;
        if (attr1->attisdropped != attr2->attisdropped)
            return false;
        if (attr1->attislocal != attr2->attislocal)
            return false;
        if (attr1->attinhcount != attr2->attinhcount)
            return false;
        if (attr1->attcollation != attr2->attcollation)
            return false;
        /* attacl, attoptions and attfdwoptions are not even present... */
    }

    if (tupdesc1->constr != NULL)
    {
        TupleConstr *constr1 = tupdesc1->constr;
        TupleConstr *constr2 = tupdesc2->constr;

        if (constr2 == NULL)
            return false;
        if (constr1->has_not_null != constr2->has_not_null)
            return false;
        n = constr1->num_defval;
        if (n != (int) constr2->num_defval)
            return false;
        for (i = 0; i < n; i++)
        {
            AttrDefault *defval1 = constr1->defval + i;
            AttrDefault *defval2 = constr2->defval;

            /*
             * We can't assume that the items are always read from the system
             * catalogs in the same order; so use the adnum field to identify
             * the matching item to compare.
             */
            for (j = 0; j < n; defval2++, j++)
            {
                if (defval1->adnum == defval2->adnum)
                    break;
            }
            if (j >= n)
                return false;
            if (strcmp(defval1->adbin, defval2->adbin) != 0)
                return false;
        }
        n = constr1->num_check;
        if (n != (int) constr2->num_check)
            return false;
        for (i = 0; i < n; i++)
        {
            ConstrCheck *check1 = constr1->check + i;
            ConstrCheck *check2 = constr2->check;

            /*
             * Similarly, don't assume that the checks are always read in the
             * same order; match them up by name and contents. (The name
             * *should* be unique, but...)
             */
            for (j = 0; j < n; check2++, j++)
            {
                if (strcmp(check1->ccname, check2->ccname) == 0 &&
                    strcmp(check1->ccbin, check2->ccbin) == 0)
                    break;
            }
            if (j >= n)
                return false;
        }
    }
    else if (tupdesc2->constr != NULL)
        return false;
    return true;
}

/*
 * TupleDescInitEntry
 *      This function initializes a single attribute structure in
 *      a previously allocated tuple descriptor.
 *
 * Note that attcollation is set to the default for the specified datatype.
 * If a nondefault collation is needed, insert it afterwards using
 * TupleDescInitEntryCollation.
 */
void
TupleDescInitEntry(TupleDesc desc,
                   AttrNumber attributeNumber,
                   const char *attributeName,
                   Oid oidtypeid,
                   int32 typmod,
                   int attdim)
{
    HeapTuple   tuple;
    Form_pg_type typeForm;
    Form_pg_attribute att;

    /*
     * sanity checks
     */
    AssertArg(PointerIsValid(desc));
    AssertArg(attributeNumber >= 1);
    AssertArg(attributeNumber <= desc->natts);

    /*
     * initialize the attribute fields
     */
    att = desc->attrs[attributeNumber - 1];

    att->attrelid = 0;          /* dummy value */

    /*
     * Note: attributeName can be NULL, because the planner doesn't always
     * fill in valid resname values in targetlists, particularly for resjunk
     * attributes.
     */
    if (attributeName != NULL)
        namestrcpy(&(att->attname), attributeName);
    else
        MemSet(NameStr(att->attname), 0, NAMEDATALEN);

    att->attstattarget = -1;
    att->attcacheoff = -1;
    att->atttypmod = typmod;

    att->attnum = attributeNumber;
    att->attndims = attdim;

    att->attnotnull = false;
    att->atthasdef = false;
    att->attisdropped = false;
    att->attislocal = true;
    att->attinhcount = 0;
    /* attacl, attoptions and attfdwoptions are not present in tupledescs */

    tuple = SearchSysCache1(TYPEOID, ObjectIdGetDatum(oidtypeid));
    if (!HeapTupleIsValid(tuple))
        elog(ERROR, "cache lookup failed for type %u", oidtypeid);
    typeForm = (Form_pg_type) GETSTRUCT(tuple);

    att->atttypid = oidtypeid;
    att->attlen = typeForm->typlen;
    att->attbyval = typeForm->typbyval;
    att->attalign = typeForm->typalign;
    att->attstorage = typeForm->typstorage;
    att->attcollation = typeForm->typcollation;

    ReleaseSysCache(tuple);
}

/*
 * TupleDescInitEntryCollation
 *
 * Assign a nondefault collation to a previously initialized tuple descriptor
 * entry.
 */
void
TupleDescInitEntryCollation(TupleDesc desc,
                            AttrNumber attributeNumber,
                            Oid collationid)
{
    /*
     * sanity checks
     */
    AssertArg(PointerIsValid(desc));
    AssertArg(attributeNumber >= 1);
    AssertArg(attributeNumber <= desc->natts);

    desc->attrs[attributeNumber - 1]->attcollation = collationid;
}


/*
 * BuildDescForRelation
 *
 * Given a relation schema (list of ColumnDef nodes), build a TupleDesc.
 *
 * Note: the default assumption is no OIDs; caller may modify the returned
 * TupleDesc if it wants OIDs.  Also, tdtypeid will need to be filled in
 * later on.
 */
TupleDesc
BuildDescForRelation(List *schema)
{
    int         natts;
    AttrNumber  attnum;
    ListCell   *l;
    TupleDesc   desc;
    bool        has_not_null;
    char       *attname;
    Oid         atttypid;
    int32       atttypmod;
    Oid         attcollation;
    int         attdim;

    /*
     * allocate a new tuple descriptor
     */
    natts = list_length(schema);
    desc = CreateTemplateTupleDesc(natts, false);
    has_not_null = false;

    attnum = 0;

    foreach(l, schema)
    {
        ColumnDef  *entry = lfirst(l);
        AclResult   aclresult;

        /*
         * for each entry in the list, get the name and type information from
         * the list and have TupleDescInitEntry fill in the attribute
         * information we need.
         */
        attnum++;

        attname = entry->colname;
        typenameTypeIdAndMod(NULL, entry->typeName, &atttypid, &atttypmod);

        aclresult = pg_type_aclcheck(atttypid, GetUserId(), ACL_USAGE);
        if (aclresult != ACLCHECK_OK)
            aclcheck_error_type(aclresult, atttypid);

        attcollation = GetColumnDefCollation(NULL, entry, atttypid);
        attdim = list_length(entry->typeName->arrayBounds);

        if (entry->typeName->setof)
            ereport(ERROR,
                    (errcode(ERRCODE_INVALID_TABLE_DEFINITION),
                     errmsg("column \"%s\" cannot be declared SETOF",
                            attname)));

        TupleDescInitEntry(desc, attnum, attname,
                           atttypid, atttypmod, attdim);

        /* Override TupleDescInitEntry's settings as requested */
        TupleDescInitEntryCollation(desc, attnum, attcollation);
        if (entry->storage)
            desc->attrs[attnum - 1]->attstorage = entry->storage;

        /* Fill in additional stuff not handled by TupleDescInitEntry */
        desc->attrs[attnum - 1]->attnotnull = entry->is_not_null;
        has_not_null |= entry->is_not_null;
        desc->attrs[attnum - 1]->attislocal = entry->is_local;
        desc->attrs[attnum - 1]->attinhcount = entry->inhcount;
    }

    if (has_not_null)
    {
        TupleConstr *constr = (TupleConstr *) palloc0(sizeof(TupleConstr));

        constr->has_not_null = true;
        constr->defval = NULL;
        constr->num_defval = 0;
        constr->check = NULL;
        constr->num_check = 0;
        desc->constr = constr;
    }
    else
    {
        desc->constr = NULL;
    }

    return desc;
}

/*
 * BuildDescFromLists
 *
 * Build a TupleDesc given lists of column names (as String nodes),
 * column type OIDs, typmods, and collation OIDs.
 *
 * No constraints are generated.
 *
 * This is essentially a cut-down version of BuildDescForRelation for use
 * with functions returning RECORD.
 */
TupleDesc
BuildDescFromLists(List *names, List *types, List *typmods, List *collations)
{
    int         natts;
    AttrNumber  attnum;
    ListCell   *l1;
    ListCell   *l2;
    ListCell   *l3;
    ListCell   *l4;
    TupleDesc   desc;

    natts = list_length(names);
    Assert(natts == list_length(types));
    Assert(natts == list_length(typmods));
    Assert(natts == list_length(collations));

    /*
     * allocate a new tuple descriptor
     */
    desc = CreateTemplateTupleDesc(natts, false);

    attnum = 0;

    l2 = list_head(types);
    l3 = list_head(typmods);
    l4 = list_head(collations);
    foreach(l1, names)
    {
        char       *attname = strVal(lfirst(l1));
        Oid         atttypid;
        int32       atttypmod;
        Oid         attcollation;

        atttypid = lfirst_oid(l2);
        l2 = lnext(l2);
        atttypmod = lfirst_int(l3);
        l3 = lnext(l3);
        attcollation = lfirst_oid(l4);
        l4 = lnext(l4);

        attnum++;

        TupleDescInitEntry(desc, attnum, attname, atttypid, atttypmod, 0);
        TupleDescInitEntryCollation(desc, attnum, attcollation);
    }

    return desc;
}