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Commit7bd7aa4

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Move EXPLAIN counter increment to heapam_scan_bitmap_next_block
Increment the lossy and exact page counters for EXPLAIN of bitmap heapscans in heapam_scan_bitmap_next_block(). Note that other table AMs willneed to do this as wellPushing the counters into heapam_scan_bitmap_next_block() is required tobe able to use the read stream API for bitmap heap scans. The bitmapiterator must be advanced from inside the read stream callback, soTBMIterateResults cannot be used as a flow control mechanism inBitmapHeapNext().Author: Melanie PlagemanReviewed-by: Tomas Vondra, Heikki LinnakangasDiscussion:https://postgr.es/m/063e4eb4-32d9-439e-a0b1-75565a9835a8%40iki.fi
1 parent8e7e672 commit7bd7aa4

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3 files changed

+27
-14
lines changed

3 files changed

+27
-14
lines changed

‎src/backend/access/heap/heapam_handler.c‎

Lines changed: 7 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -2115,7 +2115,8 @@ heapam_estimate_rel_size(Relation rel, int32 *attr_widths,
21152115

21162116
staticbool
21172117
heapam_scan_bitmap_next_block(TableScanDescscan,
2118-
TBMIterateResult*tbmres)
2118+
TBMIterateResult*tbmres,
2119+
uint64*lossy_pages,uint64*exact_pages)
21192120
{
21202121
HeapScanDeschscan= (HeapScanDesc)scan;
21212122
BlockNumberblock=tbmres->blockno;
@@ -2243,6 +2244,11 @@ heapam_scan_bitmap_next_block(TableScanDesc scan,
22432244
Assert(ntup <=MaxHeapTuplesPerPage);
22442245
hscan->rs_ntuples=ntup;
22452246

2247+
if (tbmres->ntuples >=0)
2248+
(*exact_pages)++;
2249+
else
2250+
(*lossy_pages)++;
2251+
22462252
returnntup>0;
22472253
}
22482254

‎src/backend/executor/nodeBitmapHeapscan.c‎

Lines changed: 3 additions & 10 deletions
Original file line numberDiff line numberDiff line change
@@ -212,8 +212,6 @@ BitmapHeapNext(BitmapHeapScanState *node)
212212

213213
for (;;)
214214
{
215-
boolvalid_block;
216-
217215
CHECK_FOR_INTERRUPTS();
218216

219217
/*
@@ -233,14 +231,9 @@ BitmapHeapNext(BitmapHeapScanState *node)
233231

234232
BitmapAdjustPrefetchIterator(node,tbmres->blockno);
235233

236-
valid_block=table_scan_bitmap_next_block(scan,tbmres);
237-
238-
if (tbmres->ntuples >=0)
239-
node->stats.exact_pages++;
240-
else
241-
node->stats.lossy_pages++;
242-
243-
if (!valid_block)
234+
if (!table_scan_bitmap_next_block(scan,tbmres,
235+
&node->stats.lossy_pages,
236+
&node->stats.exact_pages))
244237
{
245238
/* AM doesn't think this block is valid, skip */
246239
continue;

‎src/include/access/tableam.h‎

Lines changed: 17 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -796,6 +796,10 @@ typedef struct TableAmRoutine
796796
* on the page have to be returned, otherwise the tuples at offsets in
797797
* `tbmres->offsets` need to be returned.
798798
*
799+
* `lossy_pages` and `exact_pages` are EXPLAIN counters that can be
800+
* incremented by the table AM to indicate whether or not the block's
801+
* representation in the bitmap is lossy.
802+
*
799803
* XXX: Currently this may only be implemented if the AM uses md.c as its
800804
* storage manager, and uses ItemPointer->ip_blkid in a manner that maps
801805
* blockids directly to the underlying storage. nodeBitmapHeapscan.c
@@ -811,7 +815,9 @@ typedef struct TableAmRoutine
811815
* scan_bitmap_next_tuple need to exist, or neither.
812816
*/
813817
bool(*scan_bitmap_next_block) (TableScanDescscan,
814-
structTBMIterateResult*tbmres);
818+
structTBMIterateResult*tbmres,
819+
uint64*lossy_pages,
820+
uint64*exact_pages);
815821

816822
/*
817823
* Fetch the next tuple of a bitmap table scan into `slot` and return true
@@ -1954,12 +1960,18 @@ table_relation_estimate_size(Relation rel, int32 *attr_widths,
19541960
* table_beginscan_bm(). Returns false if there are no tuples to be found on
19551961
* the page, true otherwise.
19561962
*
1963+
* `lossy_pages` and `exact_pages` are EXPLAIN counters that can be
1964+
* incremented by the table AM to indicate whether or not the block's
1965+
* representation in the bitmap is lossy.
1966+
*
19571967
* Note, this is an optionally implemented function, therefore should only be
19581968
* used after verifying the presence (at plan time or such).
19591969
*/
19601970
staticinlinebool
19611971
table_scan_bitmap_next_block(TableScanDescscan,
1962-
structTBMIterateResult*tbmres)
1972+
structTBMIterateResult*tbmres,
1973+
uint64*lossy_pages,
1974+
uint64*exact_pages)
19631975
{
19641976
/*
19651977
* We don't expect direct calls to table_scan_bitmap_next_block with valid
@@ -1970,7 +1982,9 @@ table_scan_bitmap_next_block(TableScanDesc scan,
19701982
elog(ERROR,"unexpected table_scan_bitmap_next_block call during logical decoding");
19711983

19721984
returnscan->rs_rd->rd_tableam->scan_bitmap_next_block(scan,
1973-
tbmres);
1985+
tbmres,
1986+
lossy_pages,
1987+
exact_pages);
19741988
}
19751989

19761990
/*

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