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tableam: Avoid relying on relation size to determine validity of tids.

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Instead add a tableam callback to do so. To avoid adding per
validation overhead, pass a scan to tuple_tid_valid. In heap's case
we'd otherwise incurred a RelationGetNumberOfBlocks() call for each
tid - which'd have added noticable overhead to nodeTidscan.c.

Author: Andres Freund
Reviewed-By: Ashwin Agrawal
Discussion: https://postgr.es/m/20190515185447.gno2jtqxyktylyvs@alap3.anarazel.de
This commit is contained in:
Andres Freund
2019-05-17 18:52:01 -07:00
parent 7f44ede594
commit 147e3722f7
7 changed files with 129 additions and 57 deletions
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10
src/backend/utils/adt/tid.c
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@ -358,6 +358,7 @@ currtid_byreloid(PG_FUNCTION_ARGS)
Relation rel;
AclResult aclresult;
Snapshot snapshot;
TableScanDesc scan;
result = (ItemPointer) palloc(sizeof(ItemPointerData));
if (!reloid)
@ -380,7 +381,9 @@ currtid_byreloid(PG_FUNCTION_ARGS)
ItemPointerCopy(tid, result);
snapshot = RegisterSnapshot(GetLatestSnapshot());
table_get_latest_tid(rel, snapshot, result);
scan = table_beginscan(rel, snapshot, 0, NULL);
table_get_latest_tid(scan, result);
table_endscan(scan);
UnregisterSnapshot(snapshot);
table_close(rel, AccessShareLock);
@ -398,6 +401,7 @@ currtid_byrelname(PG_FUNCTION_ARGS)
Relation rel;
AclResult aclresult;
Snapshot snapshot;
TableScanDesc scan;
relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname));
rel = table_openrv(relrv, AccessShareLock);
@ -415,7 +419,9 @@ currtid_byrelname(PG_FUNCTION_ARGS)
ItemPointerCopy(tid, result);
snapshot = RegisterSnapshot(GetLatestSnapshot());
table_get_latest_tid(rel, snapshot, result);
scan = table_beginscan(rel, snapshot, 0, NULL);
table_get_latest_tid(scan, result);
table_endscan(scan);
UnregisterSnapshot(snapshot);
table_close(rel, AccessShareLock);