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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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27
src/backend/access/table/tableam.c
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@@ -213,6 +213,33 @@ table_index_fetch_tuple_check(Relation rel,
}
/* ------------------------------------------------------------------------
* Functions for non-modifying operations on individual tuples
* ------------------------------------------------------------------------
*/
void
table_get_latest_tid(TableScanDesc scan, ItemPointer tid)
{
Relation rel = scan->rs_rd;
const TableAmRoutine *tableam = rel->rd_tableam;
/*
* Since this can be called with user-supplied TID, don't trust the input
* too much.
*/
if (!tableam->tuple_tid_valid(scan, tid))
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("tid (%u, %u) is not valid for relation for relation \"%s\"",
ItemPointerGetBlockNumberNoCheck(tid),
ItemPointerGetOffsetNumberNoCheck(tid),
RelationGetRelationName(rel))));
return tableam->tuple_get_latest_tid(scan, tid);
}
/* ----------------------------------------------------------------------------
* Functions to make modifications a bit simpler.
* ----------------------------------------------------------------------------