When testing commit c6b9204 with CLOBBER_CACHE_ALWAYS, of the 20 hours for
check-world, 001_rep_changes.pl took 1.8 hours. At commit 5406513, the test
failed at a poll_query_until() timeout[1]. The slow part is the logical
replication of "DELETE FROM tab_ins WHERE a > 0", which deletes 100 records
from a table of ~1100 records, using RelationFindReplTupleSeq().
tuples_equal() called lookup_type_cache() for every comparison. Performing
those lookups once per RelationFindReplTupleSeq(), as attached, cut the test's
runtime by an order of magnitude. While performance for CLOBBER_CACHE_ALWAYS
is not important, this is consistent with record_eq() and is easy. I'm
slightly inclined not to back-patch it, though.
[1] This seemed to result from the poll query being 2-3x faster at commit
5406513, not from logical replication being slower. (poll_query_until() times
out after 1800 polls separated by 0.1s sleeps, however long that takes.) I
had guessed that commit 1c7a0b3 greatly accelerated this test case, but it
gave about a 4% improvement under CLOBBER_CACHE_ALWAYS.
Author: Noah Misch <n...@leadboat.com>
Commit: Noah Misch <n...@leadboat.com>
Optimize RelationFindReplTupleSeq() for CLOBBER_CACHE_ALWAYS.
Specifically, remember lookup_type_cache() results instead of retrieving
them once per comparison. Under CLOBBER_CACHE_ALWAYS, this reduced
src/test/subscription/t/001_rep_changes.pl elapsed time by an order of
magnitude, which reduced check-world elapsed time by 9%.
Reviewed by FIXME.
Discussion: https://postgr.es/m/FIXME
diff --git a/src/backend/executor/execReplication.c
b/src/backend/executor/execReplication.c
index 7194bec..58448ba 100644
--- a/src/backend/executor/execReplication.c
+++ b/src/backend/executor/execReplication.c
@@ -225,7 +225,8 @@ retry:
* Compare the tuples in the slots by checking if they have equal values.
*/
static bool
-tuples_equal(TupleTableSlot *slot1, TupleTableSlot *slot2)
+tuples_equal(TupleTableSlot *slot1, TupleTableSlot *slot2,
+ TypeCacheEntry **eq)
{
int attrnum;
@@ -256,12 +257,18 @@ tuples_equal(TupleTableSlot *slot1, TupleTableSlot *slot2)
att = TupleDescAttr(slot1->tts_tupleDescriptor, attrnum);
- typentry = lookup_type_cache(att->atttypid,
TYPECACHE_EQ_OPR_FINFO);
- if (!OidIsValid(typentry->eq_opr_finfo.fn_oid))
- ereport(ERROR,
- (errcode(ERRCODE_UNDEFINED_FUNCTION),
- errmsg("could not identify an equality
operator for type %s",
-
format_type_be(att->atttypid))));
+ typentry = eq[attrnum];
+ if (typentry == NULL)
+ {
+ typentry = lookup_type_cache(att->atttypid,
+
TYPECACHE_EQ_OPR_FINFO);
+ if (!OidIsValid(typentry->eq_opr_finfo.fn_oid))
+ ereport(ERROR,
+
(errcode(ERRCODE_UNDEFINED_FUNCTION),
+ errmsg("could not identify an
equality operator for type %s",
+
format_type_be(att->atttypid))));
+ eq[attrnum] = typentry;
+ }
if (!DatumGetBool(FunctionCall2Coll(&typentry->eq_opr_finfo,
att->attcollation,
@@ -290,12 +297,15 @@ RelationFindReplTupleSeq(Relation rel, LockTupleMode
lockmode,
TupleTableSlot *scanslot;
TableScanDesc scan;
SnapshotData snap;
+ TypeCacheEntry **eq;
TransactionId xwait;
bool found;
TupleDesc desc PG_USED_FOR_ASSERTS_ONLY = RelationGetDescr(rel);
Assert(equalTupleDescs(desc, outslot->tts_tupleDescriptor));
+ eq = palloc0(sizeof(*eq) * outslot->tts_tupleDescriptor->natts);
+
/* Start a heap scan. */
InitDirtySnapshot(snap);
scan = table_beginscan(rel, &snap, 0, NULL);
@@ -309,7 +319,7 @@ retry:
/* Try to find the tuple */
while (table_scan_getnextslot(scan, ForwardScanDirection, scanslot))
{
- if (!tuples_equal(scanslot, searchslot))
+ if (!tuples_equal(scanslot, searchslot, eq))
continue;
found = true;
