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tableam: Add and use table_fetch_row_version().

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This is essentially the tableam version of heapam_fetch(),
i.e. fetching a tuple identified by a tid, performing visibility
checks.

Note that this different from table_index_fetch_tuple(), which is for
index lookups. It therefore has to handle a tid pointing to an earlier
version of a tuple if the AM uses an optimization like heap's HOT. Add
comments to that end.

This commit removes the stats_relation argument from heap_fetch, as
it's been unused for a long time.

Author: Andres Freund
Reviewed-By: Haribabu Kommi
Discussion: https://postgr.es/m/20180703070645.wchpu5muyto5n647@alap3.anarazel.de
This commit is contained in:
Andres Freund
2019-03-25 00:13:42 -07:00
parent c77e12208c
commit 9a8ee1dc65
9 changed files with 91 additions and 111 deletions
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16
src/backend/executor/nodeTidscan.c
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@@ -310,7 +310,6 @@ TidNext(TidScanState *node)
Relation heapRelation;
HeapTuple tuple;
TupleTableSlot *slot;
Buffer buffer = InvalidBuffer;
ItemPointerData *tidList;
int numTids;
bool bBackward;
@@ -376,19 +375,10 @@ TidNext(TidScanState *node)
if (node->tss_isCurrentOf)
heap_get_latest_tid(heapRelation, snapshot, &tuple->t_self);
if (heap_fetch(heapRelation, snapshot, tuple, &buffer, NULL))
{
/*
* Store the scanned tuple in the scan tuple slot of the scan
* state, transferring the pin to the slot.
*/
ExecStorePinnedBufferHeapTuple(tuple, /* tuple to store */
slot, /* slot to store in */
buffer); /* buffer associated with
* tuple */
if (table_fetch_row_version(heapRelation, &tuple->t_self, snapshot,
slot))
return slot;
}
/* Bad TID or failed snapshot qual; try next */
if (bBackward)
node->tss_TidPtr--;