pg_collation.c

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/*-------------------------------------------------------------------------
 *
 * pg_collation.c
 *    routines to support manipulation of the pg_collation relation
 *
 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *    src/backend/catalog/pg_collation.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_collation.h"
#include "catalog/pg_namespace.h"
#include "mb/pg_wchar.h"
#include "utils/builtins.h"
#include "utils/rel.h"
#include "utils/syscache.h"
 
 
/*
 * CollationCreate
 *
 * Add a new tuple to pg_collation.
 *
 * if_not_exists: if true, don't fail on duplicate name, just print a notice
 * and return InvalidOid.
 * quiet: if true, don't fail on duplicate name, just silently return
 * InvalidOid (overrides if_not_exists).
 */
Oid
CollationCreate(const char *collname, Oid collnamespace,
                Oid collowner,
                char collprovider,
                bool collisdeterministic,
                int32 collencoding,
                const char *collcollate, const char *collctype,
                const char *colllocale,
                const char *collicurules,
                const char *collversion,
                bool if_not_exists,
                bool quiet)
{
    Relation    rel;
    TupleDesc   tupDesc;
    HeapTuple   tup;
    Datum       values[Natts_pg_collation];
    bool        nulls[Natts_pg_collation];
    NameData    name_name;
    Oid         oid;
    ObjectAddress myself,
                referenced;
 
    Assert(collname);
    Assert(collnamespace);
    Assert(collowner);
    Assert((collprovider == COLLPROVIDER_LIBC &&
            collcollate && collctype && !colllocale) ||
           (collprovider != COLLPROVIDER_LIBC &&
            !collcollate && !collctype && colllocale));
 
    /*
     * Make sure there is no existing collation of same name & encoding.
     *
     * This would be caught by the unique index anyway; we're just giving a
     * friendlier error message.  The unique index provides a backstop against
     * race conditions.
     */
    oid = GetSysCacheOid3(COLLNAMEENCNSP,
                          Anum_pg_collation_oid,
                          PointerGetDatum(collname),
                          Int32GetDatum(collencoding),
                          ObjectIdGetDatum(collnamespace));
    if (OidIsValid(oid))
    {
        if (quiet)
            return InvalidOid;
        else if (if_not_exists)
        {
            /*
             * If we are in an extension script, insist that the pre-existing
             * object be a member of the extension, to avoid security risks.
             */
            ObjectAddressSet(myself, CollationRelationId, oid);
            checkMembershipInCurrentExtension(&myself);
 
            /* OK to skip */
            ereport(NOTICE,
                    (errcode(ERRCODE_DUPLICATE_OBJECT),
                     collencoding == -1
                     ? errmsg("collation \"%s\" already exists, skipping",
                              collname)
                     : errmsg("collation \"%s\" for encoding \"%s\" already exists, skipping",
                              collname, pg_encoding_to_char(collencoding))));
            return InvalidOid;
        }
        else
            ereport(ERROR,
                    (errcode(ERRCODE_DUPLICATE_OBJECT),
                     collencoding == -1
                     ? errmsg("collation \"%s\" already exists",
                              collname)
                     : errmsg("collation \"%s\" for encoding \"%s\" already exists",
                              collname, pg_encoding_to_char(collencoding))));
    }
 
    /* open pg_collation; see below about the lock level */
    rel = table_open(CollationRelationId, ShareRowExclusiveLock);
 
    /*
     * Also forbid a specific-encoding collation shadowing an any-encoding
     * collation, or an any-encoding collation being shadowed (see
     * get_collation_name()).  This test is not backed up by the unique index,
     * so we take a ShareRowExclusiveLock earlier, to protect against
     * concurrent changes fooling this check.
     */
    if (collencoding == -1)
        oid = GetSysCacheOid3(COLLNAMEENCNSP,
                              Anum_pg_collation_oid,
                              PointerGetDatum(collname),
                              Int32GetDatum(GetDatabaseEncoding()),
                              ObjectIdGetDatum(collnamespace));
    else
        oid = GetSysCacheOid3(COLLNAMEENCNSP,
                              Anum_pg_collation_oid,
                              PointerGetDatum(collname),
                              Int32GetDatum(-1),
                              ObjectIdGetDatum(collnamespace));
    if (OidIsValid(oid))
    {
        if (quiet)
        {
            table_close(rel, NoLock);
            return InvalidOid;
        }
        else if (if_not_exists)
        {
            /*
             * If we are in an extension script, insist that the pre-existing
             * object be a member of the extension, to avoid security risks.
             */
            ObjectAddressSet(myself, CollationRelationId, oid);
            checkMembershipInCurrentExtension(&myself);
 
            /* OK to skip */
            table_close(rel, NoLock);
            ereport(NOTICE,
                    (errcode(ERRCODE_DUPLICATE_OBJECT),
                     errmsg("collation \"%s\" already exists, skipping",
                            collname)));
            return InvalidOid;
        }
        else
            ereport(ERROR,
                    (errcode(ERRCODE_DUPLICATE_OBJECT),
                     errmsg("collation \"%s\" already exists",
                            collname)));
    }
 
    tupDesc = RelationGetDescr(rel);
 
    /* form a tuple */
    memset(nulls, 0, sizeof(nulls));
 
    namestrcpy(&name_name, collname);
    oid = GetNewOidWithIndex(rel, CollationOidIndexId,
                             Anum_pg_collation_oid);
    values[Anum_pg_collation_oid - 1] = ObjectIdGetDatum(oid);
    values[Anum_pg_collation_collname - 1] = NameGetDatum(&name_name);
    values[Anum_pg_collation_collnamespace - 1] = ObjectIdGetDatum(collnamespace);
    values[Anum_pg_collation_collowner - 1] = ObjectIdGetDatum(collowner);
    values[Anum_pg_collation_collprovider - 1] = CharGetDatum(collprovider);
    values[Anum_pg_collation_collisdeterministic - 1] = BoolGetDatum(collisdeterministic);
    values[Anum_pg_collation_collencoding - 1] = Int32GetDatum(collencoding);
    if (collcollate)
        values[Anum_pg_collation_collcollate - 1] = CStringGetTextDatum(collcollate);
    else
        nulls[Anum_pg_collation_collcollate - 1] = true;
    if (collctype)
        values[Anum_pg_collation_collctype - 1] = CStringGetTextDatum(collctype);
    else
        nulls[Anum_pg_collation_collctype - 1] = true;
    if (colllocale)
        values[Anum_pg_collation_colllocale - 1] = CStringGetTextDatum(colllocale);
    else
        nulls[Anum_pg_collation_colllocale - 1] = true;
    if (collicurules)
        values[Anum_pg_collation_collicurules - 1] = CStringGetTextDatum(collicurules);
    else
        nulls[Anum_pg_collation_collicurules - 1] = true;
    if (collversion)
        values[Anum_pg_collation_collversion - 1] = CStringGetTextDatum(collversion);
    else
        nulls[Anum_pg_collation_collversion - 1] = true;
 
    tup = heap_form_tuple(tupDesc, values, nulls);
 
    /* insert a new tuple */
    CatalogTupleInsert(rel, tup);
    Assert(OidIsValid(oid));
 
    /* set up dependencies for the new collation */
    myself.classId = CollationRelationId;
    myself.objectId = oid;
    myself.objectSubId = 0;
 
    /* create dependency on namespace */
    referenced.classId = NamespaceRelationId;
    referenced.objectId = collnamespace;
    referenced.objectSubId = 0;
    recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
 
    /* create dependency on owner */
    recordDependencyOnOwner(CollationRelationId, oid, collowner);
 
    /* dependency on extension */
    recordDependencyOnCurrentExtension(&myself, false);
 
    /* Post creation hook for new collation */
    InvokeObjectPostCreateHook(CollationRelationId, oid, 0);
 
    heap_freetuple(tup);
    table_close(rel, NoLock);
 
    return oid;
}