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Use an index to get FDWs that depend on extensions (#7574) 

DESCRIPTION: Fix performance issue when distributing a table that
depends on an extension

When the database contains many objects this function would show up in
profiles because it was doing a sequence scan on pg_depend. And with
many objects pg_depend can get very large.

This starts using an index scan to only look for rows containing FDWs,
of which there are expected to be very few (often even zero).
pull/7580/head^2
Jelte Fennema-Nio 2024-04-15 14:42:56 +02:00 committed by GitHub
parent cdf51da458
commit 16604a6601
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GPG Key ID: B5690EEEBB952194
1 changed files with 6 additions and 13 deletions
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19
src/backend/distributed/commands/extension.c
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@ -1093,33 +1093,26 @@ List *
GetDependentFDWsToExtension(Oid extensionId) GetDependentFDWsToExtension(Oid extensionId)
{ {
List *extensionFDWs = NIL; List *extensionFDWs = NIL;
ScanKeyData key[3]; ScanKeyData key[1];
int scanKeyCount = 3;
HeapTuple tup; HeapTuple tup;
Relation pgDepend = table_open(DependRelationId, AccessShareLock); Relation pgDepend = table_open(DependRelationId, AccessShareLock);
ScanKeyInit(&key[0], ScanKeyInit(&key[0],
Anum_pg_depend_refclassid,
BTEqualStrategyNumber, F_OIDEQ,
ObjectIdGetDatum(ExtensionRelationId));
ScanKeyInit(&key[1],
Anum_pg_depend_refobjid,
BTEqualStrategyNumber, F_OIDEQ,
ObjectIdGetDatum(extensionId));
ScanKeyInit(&key[2],
Anum_pg_depend_classid, Anum_pg_depend_classid,
BTEqualStrategyNumber, F_OIDEQ, BTEqualStrategyNumber, F_OIDEQ,
ObjectIdGetDatum(ForeignDataWrapperRelationId)); ObjectIdGetDatum(ForeignDataWrapperRelationId));
SysScanDesc scan = systable_beginscan(pgDepend, InvalidOid, false, SysScanDesc scan = systable_beginscan(pgDepend, DependDependerIndexId, true,
NULL, scanKeyCount, key); NULL, lengthof(key), key);
while (HeapTupleIsValid(tup = systable_getnext(scan))) while (HeapTupleIsValid(tup = systable_getnext(scan)))
{ {
Form_pg_depend pgDependEntry = (Form_pg_depend) GETSTRUCT(tup); Form_pg_depend pgDependEntry = (Form_pg_depend) GETSTRUCT(tup);
if (pgDependEntry->deptype == DEPENDENCY_EXTENSION) if (pgDependEntry->deptype == DEPENDENCY_EXTENSION &&
pgDependEntry->refclassid == ExtensionRelationId &&
pgDependEntry->refobjid == extensionId)
{ {
extensionFDWs = lappend_oid(extensionFDWs, pgDependEntry->objid); extensionFDWs = lappend_oid(extensionFDWs, pgDependEntry->objid);
} }