pg_namespace.c

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/*-------------------------------------------------------------------------
 *
 * pg_namespace.c
 *    routines to support manipulation of the pg_namespace relation
 *
 * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    src/backend/catalog/pg_namespace.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "access/htup_details.h"
#include "access/table.h"
#include "catalog/catalog.h"
#include "catalog/dependency.h"
#include "catalog/indexing.h"
#include "catalog/objectaccess.h"
#include "catalog/pg_namespace.h"
#include "utils/builtins.h"
#include "utils/rel.h"
#include "utils/syscache.h"


/* ----------------
 * NamespaceCreate
 *
 * Create a namespace (schema) with the given name and owner OID.
 *
 * If isTemp is true, this schema is a per-backend schema for holding
 * temporary tables.  Currently, it is used to prevent it from being
 * linked as a member of any active extension.  (If someone does CREATE
 * TEMP TABLE in an extension script, we don't want the temp schema to
 * become part of the extension). And to avoid checking for default ACL
 * for temp namespace (as it is not necessary).
 * ---------------
 */
Oid
NamespaceCreate(const char *nspName, Oid ownerId, bool isTemp)
{
    Relation    nspdesc;
    HeapTuple   tup;
    Oid         nspoid;
    bool        nulls[Natts_pg_namespace];
    Datum       values[Natts_pg_namespace];
    NameData    nname;
    TupleDesc   tupDesc;
    ObjectAddress myself;
    int         i;
    Acl        *nspacl;

    /* sanity checks */
    if (!nspName)
        elog(ERROR, "no namespace name supplied");

    /* make sure there is no existing namespace of same name */
    if (SearchSysCacheExists1(NAMESPACENAME, PointerGetDatum(nspName)))
        ereport(ERROR,
                (errcode(ERRCODE_DUPLICATE_SCHEMA),
                 errmsg("schema \"%s\" already exists", nspName)));

    if (!isTemp)
        nspacl = get_user_default_acl(OBJECT_SCHEMA, ownerId,
                                      InvalidOid);
    else
        nspacl = NULL;

    nspdesc = table_open(NamespaceRelationId, RowExclusiveLock);
    tupDesc = nspdesc->rd_att;

    /* initialize nulls and values */
    for (i = 0; i < Natts_pg_namespace; i++)
    {
        nulls[i] = false;
        values[i] = (Datum) NULL;
    }

    nspoid = GetNewOidWithIndex(nspdesc, NamespaceOidIndexId,
                                Anum_pg_namespace_oid);
    values[Anum_pg_namespace_oid - 1] = ObjectIdGetDatum(nspoid);
    namestrcpy(&nname, nspName);
    values[Anum_pg_namespace_nspname - 1] = NameGetDatum(&nname);
    values[Anum_pg_namespace_nspowner - 1] = ObjectIdGetDatum(ownerId);
    if (nspacl != NULL)
        values[Anum_pg_namespace_nspacl - 1] = PointerGetDatum(nspacl);
    else
        nulls[Anum_pg_namespace_nspacl - 1] = true;


    tup = heap_form_tuple(tupDesc, values, nulls);

    CatalogTupleInsert(nspdesc, tup);
    Assert(OidIsValid(nspoid));

    table_close(nspdesc, RowExclusiveLock);

    /* Record dependencies */
    myself.classId = NamespaceRelationId;
    myself.objectId = nspoid;
    myself.objectSubId = 0;

    /* dependency on owner */
    recordDependencyOnOwner(NamespaceRelationId, nspoid, ownerId);

    /* dependencies on roles mentioned in default ACL */
    recordDependencyOnNewAcl(NamespaceRelationId, nspoid, 0, ownerId, nspacl);

    /* dependency on extension ... but not for magic temp schemas */
    if (!isTemp)
        recordDependencyOnCurrentExtension(&myself, false);

    /* Post creation hook for new schema */
    InvokeObjectPostCreateHook(NamespaceRelationId, nspoid, 0);

    return nspoid;
}