v5-0001-Use-streaming-read-API-in-pgstatindex-functions.patch

From fe917cbd3c5dc5e62a5472434e12ad611463e40a Mon Sep 17 00:00:00 2001
From: alterego655 <824662526@qq.com>
Date: Thu, 16 Oct 2025 17:04:23 +0800
Subject: [PATCH v5] Use streaming read API in pgstatindex functions
MIME-Version: 1.0
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Replace synchronous ReadBufferExtended() loops with the streaming read
API in pgstatindex_impl() and pgstathashindex().

Author: Xuneng Zhou <xunengzhou@gmail.com>Reviewed-by: Nazir Bilal Yavuz <byavuz81@gmail.com>
Reviewed-by: wenhui qiu <qiuwenhuifx@gmail.com>
Reviewed-by: Shinya Kato <shinya11.kato@gmail.com>
---
 contrib/pgstattuple/pgstatindex.c | 57 ++++++++++++++++++++++++++-----
 1 file changed, 48 insertions(+), 9 deletions(-)

diff --git a/contrib/pgstattuple/pgstatindex.c b/contrib/pgstattuple/pgstatindex.c
index 40823d54fca..e9c06de4e52 100644
--- a/contrib/pgstattuple/pgstatindex.c
+++ b/contrib/pgstattuple/pgstatindex.c
@@ -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 +218,8 @@ pgstatindex_impl(Relation rel, FunctionCallInfo fcinfo)
 	BlockNumber blkno;
 	BTIndexStat indexStat;
 	BufferAccessStrategy bstrategy = GetAccessStrategy(BAS_BULKREAD);
+	BlockRangeReadStreamPrivate p;
+	ReadStream *stream;
 
 	if (!IS_INDEX(rel) || !IS_BTREE(rel))
 		ereport(ERROR,
@@ -273,10 +276,26 @@ 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);
 
+	p.current_blocknum = BTREE_METAPAGE + 1;
+	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 = 1; blkno < nblocks; blkno++)
 	{
 		Buffer		buffer;
@@ -285,8 +304,7 @@ 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 +340,12 @@ 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);
 
 	/*----------------------------
@@ -596,6 +615,8 @@ pgstathashindex(PG_FUNCTION_ARGS)
 	HashMetaPage metap;
 	float8		free_percent;
 	uint64		total_space;
+	BlockRangeReadStreamPrivate p;
+	ReadStream *stream;
 
 	rel = relation_open(relid, AccessShareLock);
 
@@ -636,7 +657,23 @@ pgstathashindex(PG_FUNCTION_ARGS)
 	/* prepare access strategy for this index */
 	bstrategy = GetAccessStrategy(BAS_BULKREAD);
 
-	/* Start from blkno 1 as 0th block is metapage */
+	/* Scan all blocks except the metapage (0th page) using streaming reads */
+	p.current_blocknum = HASH_METAPAGE + 1;
+	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 = 1; blkno < nblocks; blkno++)
 	{
 		Buffer		buf;
@@ -644,8 +681,7 @@ pgstathashindex(PG_FUNCTION_ARGS)
 
 		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);
 
@@ -690,6 +726,9 @@ pgstathashindex(PG_FUNCTION_ARGS)
 		UnlockReleaseBuffer(buf);
 	}
 
+	Assert(read_stream_next_buffer(stream, NULL) == InvalidBuffer);
+	read_stream_end(stream);
+
 	/* Done accessing the index */
 	index_close(rel, AccessShareLock);
 
-- 
2.51.0