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Use streaming I/O in ANALYZE.

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The ANALYZE command prefetches and reads sample blocks chosen by a
BlockSampler algorithm. Instead of calling [Prefetch|Read]Buffer() for
each block, ANALYZE now uses the streaming API introduced in b5a9b18cd0.

Author: Nazir Bilal Yavuz <byavuz81@gmail.com>
Reviewed-by: Melanie Plageman <melanieplageman@gmail.com>
Reviewed-by: Andres Freund <andres@anarazel.de>
Reviewed-by: Jakub Wartak <jakub.wartak@enterprisedb.com>
Reviewed-by: Heikki Linnakangas <hlinnaka@iki.fi>
Reviewed-by: Thomas Munro <thomas.munro@gmail.com>
Discussion: https://postgr.es/m/flat/CAN55FZ0UhXqk9v3y-zW_fp4-WCp43V8y0A72xPmLkOM%2B6M%2BmJg%40mail.gmail.com
This commit is contained in:
Thomas Munro
2024-04-08 13:16:20 +12:00
parent f587338dec
commit 041b96802e
3 changed files with 43 additions and 76 deletions
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29
src/backend/access/heap/heapam_handler.c
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@@ -1055,33 +1055,36 @@ heapam_relation_copy_for_cluster(Relation OldHeap, Relation NewHeap,
}
/*
* Prepare to analyze block `blockno` of `scan`. The scan has been started
* Prepare to analyze the next block in the read stream. Returns false if
* the stream is exhausted and true otherwise. The scan must have been started
* with SO_TYPE_ANALYZE option.
*
* This routine holds a buffer pin and lock on the heap page. They are held
* until heapam_scan_analyze_next_tuple() returns false. That is until all the
* items of the heap page are analyzed.
*/
void
heapam_scan_analyze_next_block(TableScanDesc scan, BlockNumber blockno,
BufferAccessStrategy bstrategy)
bool
heapam_scan_analyze_next_block(TableScanDesc scan, ReadStream *stream)
{
HeapScanDesc hscan = (HeapScanDesc) scan;
/*
* We must maintain a pin on the target page's buffer to ensure that
* concurrent activity - e.g. HOT pruning - doesn't delete tuples out from
* under us. Hence, pin the page until we are done looking at it. We
* also choose to hold sharelock on the buffer throughout --- we could
* release and re-acquire sharelock for each tuple, but since we aren't
* doing much work per tuple, the extra lock traffic is probably better
* avoided.
* under us. It comes from the stream already pinned. We also choose to
* hold sharelock on the buffer throughout --- we could release and
* re-acquire sharelock for each tuple, but since we aren't doing much
* work per tuple, the extra lock traffic is probably better avoided.
*/
hscan->rs_cblock = blockno;
hscan->rs_cindex = FirstOffsetNumber;
hscan->rs_cbuf = ReadBufferExtended(scan->rs_rd, MAIN_FORKNUM,
blockno, RBM_NORMAL, bstrategy);
hscan->rs_cbuf = read_stream_next_buffer(stream, NULL);
if (!BufferIsValid(hscan->rs_cbuf))
return false;
LockBuffer(hscan->rs_cbuf, BUFFER_LOCK_SHARE);
hscan->rs_cblock = BufferGetBlockNumber(hscan->rs_cbuf);
hscan->rs_cindex = FirstOffsetNumber;
return true;
}
/*