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Add pg_get_serial_sequence() function, and cause pg_dump to use it.

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This eliminates the assumption that a serial column's sequence will
have the same name on reload that it was given in the original database.

Christopher Kings-Lynne
This commit is contained in:
Tom Lane
2004-06-25 17:20:29 +00:00
parent ef2880263c
commit a0e842d81b
6 changed files with 185 additions and 29 deletions
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114
src/backend/utils/adt/ruleutils.c
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@@ -3,7 +3,7 @@
* back to source text
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/adt/ruleutils.c,v 1.173 2004/06/18 06:13:49 tgl Exp $
* $PostgreSQL: pgsql/src/backend/utils/adt/ruleutils.c,v 1.174 2004/06/25 17:20:24 tgl Exp $
*
* This software is copyrighted by Jan Wieck - Hamburg.
*
@@ -42,12 +42,14 @@
#include "access/genam.h"
#include "catalog/catname.h"
#include "catalog/dependency.h"
#include "catalog/heap.h"
#include "catalog/index.h"
#include "catalog/indexing.h"
#include "catalog/namespace.h"
#include "catalog/pg_cast.h"
#include "catalog/pg_constraint.h"
#include "catalog/pg_depend.h"
#include "catalog/pg_index.h"
#include "catalog/pg_opclass.h"
#include "catalog/pg_operator.h"
@@ -1232,6 +1234,116 @@ pg_get_userbyid(PG_FUNCTION_ARGS)
PG_RETURN_NAME(result);
}
/*
* pg_get_serial_sequence
* Get the name of the sequence used by a serial column,
* formatted suitably for passing to setval, nextval or currval.
*/
Datum
pg_get_serial_sequence(PG_FUNCTION_ARGS)
{
text *tablename = PG_GETARG_TEXT_P(0);
text *columnname = PG_GETARG_TEXT_P(1);
RangeVar *tablerv;
Oid tableOid;
char *column;
AttrNumber attnum;
Oid sequenceId = InvalidOid;
Relation depRel;
ScanKeyData key[3];
SysScanDesc scan;
HeapTuple tup;
/* Get the OID of the table */
tablerv = makeRangeVarFromNameList(textToQualifiedNameList(tablename,
"pg_get_serial_sequence"));
tableOid = RangeVarGetRelid(tablerv, false);
/* Get the number of the column */
column = DatumGetCString(DirectFunctionCall1(textout,
PointerGetDatum(columnname)));
attnum = get_attnum(tableOid, column);
if (attnum == InvalidAttrNumber)
ereport(ERROR,
(errcode(ERRCODE_UNDEFINED_COLUMN),
errmsg("column \"%s\" of relation \"%s\" does not exist",
column, tablerv->relname)));
/* Search the dependency table for the dependent sequence */
depRel = heap_openr(DependRelationName, AccessShareLock);
ScanKeyInit(&key[0],
Anum_pg_depend_refclassid,
BTEqualStrategyNumber, F_OIDEQ,
ObjectIdGetDatum(RelOid_pg_class));
ScanKeyInit(&key[1],
Anum_pg_depend_refobjid,
BTEqualStrategyNumber, F_OIDEQ,
ObjectIdGetDatum(tableOid));
ScanKeyInit(&key[2],
Anum_pg_depend_refobjsubid,
BTEqualStrategyNumber, F_INT4EQ,
Int32GetDatum(attnum));
scan = systable_beginscan(depRel, DependReferenceIndex, true,
SnapshotNow, 3, key);
while (HeapTupleIsValid(tup = systable_getnext(scan)))
{
Form_pg_depend deprec = (Form_pg_depend) GETSTRUCT(tup);
/*
* We assume any internal dependency of a relation on a column
* must be what we are looking for.
*/
if (deprec->classid == RelOid_pg_class &&
deprec->objsubid == 0 &&
deprec->deptype == DEPENDENCY_INTERNAL)
{
sequenceId = deprec->objid;
break;
}
}
systable_endscan(scan);
heap_close(depRel, AccessShareLock);
if (OidIsValid(sequenceId))
{
HeapTuple classtup;
Form_pg_class classtuple;
char *nspname;
char *result;
/* Get the sequence's pg_class entry */
classtup = SearchSysCache(RELOID,
ObjectIdGetDatum(sequenceId),
0, 0, 0);
if (!HeapTupleIsValid(classtup))
elog(ERROR, "cache lookup failed for relation %u", sequenceId);
classtuple = (Form_pg_class) GETSTRUCT(classtup);
/* Get the namespace */
nspname = get_namespace_name(classtuple->relnamespace);
if (!nspname)
elog(ERROR, "cache lookup failed for namespace %u",
classtuple->relnamespace);
/* And construct the result string */
result = quote_qualified_identifier(nspname,
NameStr(classtuple->relname));
ReleaseSysCache(classtup);
PG_RETURN_TEXT_P(string_to_text(result));
}
PG_RETURN_NULL();
}
/* ----------
* deparse_expression - General utility for deparsing expressions
*