Github user hornn commented on a diff in the pull request:
https://github.com/apache/incubator-hawq/pull/1002#discussion_r86451395
--- 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 --
why not use `MAX(oid)` like it was before? is it because it's not supported
by caql?
Also, maybe add `LIMIT 1` to the query because we only need the first row.
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