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%.

Discussion: https://postgr.es/m/20200406085420[email protected]

diff --git a/src/backend/executor/execReplication.c b/src/backend/executor/execReplication.c
index dc8a01a5cd51672e874baeeaf62492cc601d2135..1418746eb8d5c5ec644aa47e5a439507ce798426 100644 (file)
--- 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;