Github user sansanichfb commented on a diff in the pull request:
https://github.com/apache/incubator-hawq/pull/1002#discussion_r86456829
--- Diff: src/backend/access/transam/varsup.c ---
@@ -474,73 +479,53 @@ ResetExternalObjectId(void)
/*
* master_highest_used_oid
- * Query the database to find the highest used Oid by
+ * Uses CAQL to find the highest used Oid by
* 1) Find all the relations that has Oids
* 2) Find max oid from those relations
*/
Oid
master_highest_used_oid(void)
{
Oid oidMax = InvalidOid;
+ Oid currentOid;
+ Form_pg_class classForm;
+ int fetchCount;
- if (SPI_OK_CONNECT != SPI_connect())
- {
- ereport(ERROR, (errcode(ERRCODE_CDB_INTERNAL_ERROR),
- errmsg("Unable to connect to execute internal
query for HCatalog.")));
- }
-
- int ret = SPI_execute("SELECT relname FROM pg_class where
relhasoids=true", true, 0);
+ cqContext *pcqOuterCtx = caql_beginscan(
+ NULL,
+ cql("SELECT * FROM pg_class where relhasoids = :1",
+ BoolGetDatum(true)));
- int rows = SPI_processed;
+ HeapTuple tuple = caql_getnext(pcqOuterCtx);
- char *tableNames[rows];
-
- if (rows == 0 || ret <= 0 || NULL == SPI_tuptable)
+ if (!HeapTupleIsValid(tuple))
{
- SPI_finish();
+ caql_endscan(pcqOuterCtx);
+ elog(DEBUG1, "Unable to get list of tables having oids");
return oidMax;
}
- TupleDesc tupdesc = SPI_tuptable->tupdesc;
- SPITupleTable *tuptable = SPI_tuptable;
-
- for (int i = 0; i < rows; i++)
- {
- HeapTuple tuple = tuptable->vals[i];
- tableNames[i] = SPI_getvalue(tuple, tupdesc, 1);
- }
-
/* construct query to get max oid from all tables with oids */
- StringInfoData sqlstr;
- initStringInfo(&sqlstr);
- appendStringInfo(&sqlstr, "SELECT max(oid) FROM (");
- for (int i = 0; i < rows; i++)
+ StringInfo sqlstr = makeStringInfo();
+ while (HeapTupleIsValid(tuple))
{
- if (i > 0)
- {
- appendStringInfo(&sqlstr, " UNION ALL ");
- }
- appendStringInfo(&sqlstr, "SELECT max(oid) AS oid FROM %s",
tableNames[i]);
- }
- appendStringInfo(&sqlstr, ") AS x");
+ classForm = (Form_pg_class) GETSTRUCT(tuple);
+ appendStringInfo(sqlstr, "SELECT oid FROM %s WHERE oid >= :1
ORDER BY oid", classForm->relname.data);
--- End diff --
I found out that caql doesn't support MAX and it supports only ORDER BY,
but doesn't support ORDER BY ... DESC so we actually need last row. Will
updated code to iterate fetchCount times and get last value.
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