From 2e46bf67114586835f4a9908f1a1f08ee8ba83a8 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Tue, 13 Mar 2012 09:51:03 -0400
Subject: [PATCH] pgstattuple: Use a BufferAccessStrategy object to avoid
cache-trashing.
Jaime Casanova, reviewed by Noah Misch, slightly modified by me.
---
contrib/pgstattuple/pgstatindex.c | 5 ++--
contrib/pgstattuple/pgstattuple.c | 42 +++++++++++++++++++++----------
2 files changed, 32 insertions(+), 15 deletions(-)
diff --git a/contrib/pgstattuple/pgstatindex.c b/contrib/pgstattuple/pgstatindex.c
index beff1b9855b..9f2ec1f2108 100644
--- a/contrib/pgstattuple/pgstatindex.c
+++ b/contrib/pgstattuple/pgstatindex.c
@@ -95,6 +95,7 @@ pgstatindex(PG_FUNCTION_ARGS)
BlockNumber nblocks;
BlockNumber blkno;
BTIndexStat indexStat;
+ BufferAccessStrategy bstrategy = GetAccessStrategy(BAS_BULKREAD);
if (!superuser())
ereport(ERROR,
@@ -122,7 +123,7 @@ pgstatindex(PG_FUNCTION_ARGS)
* Read metapage
*/
{
- Buffer buffer = ReadBuffer(rel, 0);
+ Buffer buffer = ReadBufferExtended(rel, MAIN_FORKNUM, 0, RBM_NORMAL, bstrategy);
Page page = BufferGetPage(buffer);
BTMetaPageData *metad = BTPageGetMeta(page);
@@ -159,7 +160,7 @@ pgstatindex(PG_FUNCTION_ARGS)
CHECK_FOR_INTERRUPTS();
/* Read and lock buffer */
- buffer = ReadBuffer(rel, blkno);
+ buffer = ReadBufferExtended(rel, MAIN_FORKNUM, blkno, RBM_NORMAL, bstrategy);
LockBuffer(buffer, BUFFER_LOCK_SHARE);
page = BufferGetPage(buffer);
diff --git a/contrib/pgstattuple/pgstattuple.c b/contrib/pgstattuple/pgstattuple.c
index 7af724f24bb..c9be8c92e4b 100644
--- a/contrib/pgstattuple/pgstattuple.c
+++ b/contrib/pgstattuple/pgstattuple.c
@@ -61,18 +61,22 @@ typedef struct pgstattuple_type
uint64 free_space; /* free/reusable space in bytes */
} pgstattuple_type;
-typedef void (*pgstat_page) (pgstattuple_type *, Relation, BlockNumber);
+typedef void (*pgstat_page) (pgstattuple_type *, Relation, BlockNumber,
+ BufferAccessStrategy);
static Datum build_pgstattuple_type(pgstattuple_type *stat,
FunctionCallInfo fcinfo);
static Datum pgstat_relation(Relation rel, FunctionCallInfo fcinfo);
static Datum pgstat_heap(Relation rel, FunctionCallInfo fcinfo);
static void pgstat_btree_page(pgstattuple_type *stat,
- Relation rel, BlockNumber blkno);
+ Relation rel, BlockNumber blkno,
+ BufferAccessStrategy bstrategy);
static void pgstat_hash_page(pgstattuple_type *stat,
- Relation rel, BlockNumber blkno);
+ Relation rel, BlockNumber blkno,
+ BufferAccessStrategy bstrategy);
static void pgstat_gist_page(pgstattuple_type *stat,
- Relation rel, BlockNumber blkno);
+ Relation rel, BlockNumber blkno,
+ BufferAccessStrategy bstrategy);
static Datum pgstat_index(Relation rel, BlockNumber start,
pgstat_page pagefn, FunctionCallInfo fcinfo);
static void pgstat_index_page(pgstattuple_type *stat, Page page,
@@ -273,12 +277,17 @@ pgstat_heap(Relation rel, FunctionCallInfo fcinfo)
BlockNumber tupblock;
Buffer buffer;
pgstattuple_type stat = {0};
+ BufferAccessStrategy bstrategy;
/* Disable syncscan because we assume we scan from block zero upwards */
scan = heap_beginscan_strat(rel, SnapshotAny, 0, NULL, true, false);
nblocks = scan->rs_nblocks; /* # blocks to be scanned */
+ /* prepare access strategy for this table */
+ bstrategy = GetAccessStrategy(BAS_BULKREAD);
+ scan->rs_strategy = bstrategy;
+
/* scan the relation */
while ((tuple = heap_getnext(scan, ForwardScanDirection)) != NULL)
{
@@ -312,7 +321,7 @@ pgstat_heap(Relation rel, FunctionCallInfo fcinfo)
{
CHECK_FOR_INTERRUPTS();
- buffer = ReadBuffer(rel, block);
+ buffer = ReadBufferExtended(rel, MAIN_FORKNUM, block, RBM_NORMAL, bstrategy);
LockBuffer(buffer, BUFFER_LOCK_SHARE);
stat.free_space += PageGetHeapFreeSpace((Page) BufferGetPage(buffer));
UnlockReleaseBuffer(buffer);
@@ -325,7 +334,7 @@ pgstat_heap(Relation rel, FunctionCallInfo fcinfo)
{
CHECK_FOR_INTERRUPTS();
- buffer = ReadBuffer(rel, block);
+ buffer = ReadBufferExtended(rel, MAIN_FORKNUM, block, RBM_NORMAL, bstrategy);
LockBuffer(buffer, BUFFER_LOCK_SHARE);
stat.free_space += PageGetHeapFreeSpace((Page) BufferGetPage(buffer));
UnlockReleaseBuffer(buffer);
@@ -343,12 +352,13 @@ pgstat_heap(Relation rel, FunctionCallInfo fcinfo)
* pgstat_btree_page -- check tuples in a btree page
*/
static void
-pgstat_btree_page(pgstattuple_type *stat, Relation rel, BlockNumber blkno)
+pgstat_btree_page(pgstattuple_type *stat, Relation rel, BlockNumber blkno,
+ BufferAccessStrategy bstrategy)
{
Buffer buf;
Page page;
- buf = ReadBuffer(rel, blkno);
+ buf = ReadBufferExtended(rel, MAIN_FORKNUM, blkno, RBM_NORMAL, bstrategy);
LockBuffer(buf, BT_READ);
page = BufferGetPage(buf);
@@ -386,13 +396,14 @@ pgstat_btree_page(pgstattuple_type *stat, Relation rel, BlockNumber blkno)
* pgstat_hash_page -- check tuples in a hash page
*/
static void
-pgstat_hash_page(pgstattuple_type *stat, Relation rel, BlockNumber blkno)
+pgstat_hash_page(pgstattuple_type *stat, Relation rel, BlockNumber blkno,
+ BufferAccessStrategy bstrategy)
{
Buffer buf;
Page page;
_hash_getlock(rel, blkno, HASH_SHARE);
- buf = _hash_getbuf(rel, blkno, HASH_READ, 0);
+ buf = _hash_getbuf_with_strategy(rel, blkno, HASH_READ, 0, bstrategy);
page = BufferGetPage(buf);
if (PageGetSpecialSize(page) == MAXALIGN(sizeof(HashPageOpaqueData)))
@@ -429,12 +440,13 @@ pgstat_hash_page(pgstattuple_type *stat, Relation rel, BlockNumber blkno)
* pgstat_gist_page -- check tuples in a gist page
*/
static void
-pgstat_gist_page(pgstattuple_type *stat, Relation rel, BlockNumber blkno)
+pgstat_gist_page(pgstattuple_type *stat, Relation rel, BlockNumber blkno,
+ BufferAccessStrategy bstrategy)
{
Buffer buf;
Page page;
- buf = ReadBuffer(rel, blkno);
+ buf = ReadBufferExtended(rel, MAIN_FORKNUM, blkno, RBM_NORMAL, bstrategy);
LockBuffer(buf, GIST_SHARE);
gistcheckpage(rel, buf);
page = BufferGetPage(buf);
@@ -461,8 +473,12 @@ pgstat_index(Relation rel, BlockNumber start, pgstat_page pagefn,
{
BlockNumber nblocks;
BlockNumber blkno;
+ BufferAccessStrategy bstrategy;
pgstattuple_type stat = {0};
+ /* prepare access strategy for this index */
+ bstrategy = GetAccessStrategy(BAS_BULKREAD);
+
blkno = start;
for (;;)
{
@@ -483,7 +499,7 @@ pgstat_index(Relation rel, BlockNumber start, pgstat_page pagefn,
{
CHECK_FOR_INTERRUPTS();
- pagefn(&stat, rel, blkno);
+ pagefn(&stat, rel, blkno, bstrategy);
}
}
--
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