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Reduce relcache access in WAL sender streaming logical changes

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get_rel_sync_entry(), which is called each time a change needs to be
logically replicated, is a rather hot code path in the WAL sender
sending logical changes.  This code path was doing a relcache access on
relkind and relpartition for each logical change, but we only need to
know this information when building or re-building the cached
information for a relation.

Some measurements prove that this is noticeable in perf profiles,
particularly when attempting to replicate changes from relations that
are not published as these cause less overhead in the WAL sender,
delaying further the replication of changes for relations that are
published.

Issue introduced in 83fd453.

Author: Hou Zhijie
Reviewed-by: Kyotaro Horiguchi, Euler Taveira
Discussion: https://postgr.es/m/OS0PR01MB5716E863AA9E591C1F010F7A947D9@OS0PR01MB5716.jpnprd01.prod.outlook.com
Backpatch-through: 13
This commit is contained in:
Michael Paquier 2022-01-05 10:27:07 +09:00
parent 913a03ec29
commit 6ce16088bf
1 changed files with 2 additions and 2 deletions
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4
src/backend/replication/pgoutput/pgoutput.c
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@ -1119,8 +1119,6 @@ static RelationSyncEntry *
get_rel_sync_entry(PGOutputData *data, Oid relid)
{
RelationSyncEntry *entry;
bool am_partition = get_rel_relispartition(relid);
char relkind = get_rel_relkind(relid);
bool found;
MemoryContext oldctx;
@ -1160,6 +1158,8 @@ get_rel_sync_entry(PGOutputData *data, Oid relid)
List *schemaPubids = GetSchemaPublications(schemaId);
ListCell *lc;
Oid publish_as_relid = relid;
bool am_partition = get_rel_relispartition(relid);
char relkind = get_rel_relkind(relid);
/* Reload publications if needed before use. */
if (!publications_valid)