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pgstattuple: Optimize btree and hash index functions with streaming read

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This commit replaces the synchronous ReadBufferExtended() loops with the
streaming read routines, affecting pgstatindex() (for btree) and
pgstathashindex() (for hash indexes).

Under test conditions similar to 6c228755ad (some dm_delay and
debug_io_direct=data), this can result in nice runtime and IO gains.

Author: Xuneng Zhou <xunengzhou@gmail.com>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Reviewed-by: Nazir Bilal Yavuz <byavuz81@gmail.com>
Discussion: https://postgr.es/m/CABPTF7VrqfbcDXqGrdLQ2xaQ=K0RzExNuw6U_GGqzSJu32wfdQ@mail.gmail.com
This commit is contained in:
Michael Paquier 2026-03-13 10:48:45 +09:00
parent a0b6ef29a5
commit 213f0079b3
1 changed files with 55 additions and 11 deletions
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66
contrib/pgstattuple/pgstatindex.c
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@ -37,6 +37,7 @@
#include "funcapi.h"
#include "miscadmin.h"
#include "storage/bufmgr.h"
#include "storage/read_stream.h"
#include "utils/rel.h"
#include "utils/varlena.h"
@ -217,6 +218,9 @@ pgstatindex_impl(Relation rel, FunctionCallInfo fcinfo)
BlockNumber blkno;
BTIndexStat indexStat;
BufferAccessStrategy bstrategy = GetAccessStrategy(BAS_BULKREAD);
BlockRangeReadStreamPrivate p;
ReadStream *stream;
BlockNumber startblk;
if (!IS_INDEX(rel) || !IS_BTREE(rel))
ereport(ERROR,
@ -273,11 +277,28 @@ pgstatindex_impl(Relation rel, FunctionCallInfo fcinfo)
indexStat.fragments = 0;
/*
* Scan all blocks except the metapage
* Scan all blocks except the metapage (0th page) using streaming reads
*/
nblocks = RelationGetNumberOfBlocks(rel);
startblk = BTREE_METAPAGE + 1;
for (blkno = 1; blkno < nblocks; blkno++)
p.current_blocknum = startblk;
p.last_exclusive = nblocks;
/*
* It is safe to use batchmode as block_range_read_stream_cb takes no
* locks.
*/
stream = read_stream_begin_relation(READ_STREAM_FULL |
READ_STREAM_USE_BATCHING,
bstrategy,
rel,
MAIN_FORKNUM,
block_range_read_stream_cb,
&p,
0);
for (blkno = startblk; blkno < nblocks; blkno++)
{
Buffer buffer;
Page page;
@ -285,8 +306,7 @@ pgstatindex_impl(Relation rel, FunctionCallInfo fcinfo)
CHECK_FOR_INTERRUPTS();
/* Read and lock buffer */
buffer = ReadBufferExtended(rel, MAIN_FORKNUM, blkno, RBM_NORMAL, bstrategy);
buffer = read_stream_next_buffer(stream, NULL);
LockBuffer(buffer, BUFFER_LOCK_SHARE);
page = BufferGetPage(buffer);
@ -322,11 +342,12 @@ pgstatindex_impl(Relation rel, FunctionCallInfo fcinfo)
else
indexStat.internal_pages++;
/* Unlock and release buffer */
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
ReleaseBuffer(buffer);
UnlockReleaseBuffer(buffer);
}
Assert(read_stream_next_buffer(stream, NULL) == InvalidBuffer);
read_stream_end(stream);
relation_close(rel, AccessShareLock);
/*----------------------------
@ -600,6 +621,9 @@ pgstathashindex(PG_FUNCTION_ARGS)
HashMetaPage metap;
float8 free_percent;
uint64 total_space;
BlockRangeReadStreamPrivate p;
ReadStream *stream;
BlockNumber startblk;
/*
* This uses relation_open() and not index_open(). The latter allows
@ -644,16 +668,33 @@ pgstathashindex(PG_FUNCTION_ARGS)
/* prepare access strategy for this index */
bstrategy = GetAccessStrategy(BAS_BULKREAD);
/* Start from blkno 1 as 0th block is metapage */
for (blkno = 1; blkno < nblocks; blkno++)
/* Scan all blocks except the metapage (0th page) using streaming reads */
startblk = HASH_METAPAGE + 1;
p.current_blocknum = startblk;
p.last_exclusive = nblocks;
/*
* It is safe to use batchmode as block_range_read_stream_cb takes no
* locks.
*/
stream = read_stream_begin_relation(READ_STREAM_FULL |
READ_STREAM_USE_BATCHING,
bstrategy,
rel,
MAIN_FORKNUM,
block_range_read_stream_cb,
&p,
0);
for (blkno = startblk; blkno < nblocks; blkno++)
{
Buffer buf;
Page page;
CHECK_FOR_INTERRUPTS();
buf = ReadBufferExtended(rel, MAIN_FORKNUM, blkno, RBM_NORMAL,
bstrategy);
buf = read_stream_next_buffer(stream, NULL);
LockBuffer(buf, BUFFER_LOCK_SHARE);
page = BufferGetPage(buf);
@ -698,6 +739,9 @@ pgstathashindex(PG_FUNCTION_ARGS)
UnlockReleaseBuffer(buf);
}
Assert(read_stream_next_buffer(stream, NULL) == InvalidBuffer);
read_stream_end(stream);
/* Done accessing the index */
relation_close(rel, AccessShareLock);