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pgstattuple: Use a BufferAccessStrategy object to avoid cache-trashing.

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Jaime Casanova, reviewed by Noah Misch, slightly modified by me.
This commit is contained in:
Robert Haas 2012-03-13 09:51:03 -04:00
parent 97c85098de
commit 2e46bf6711
2 changed files with 32 additions and 15 deletions
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5
contrib/pgstattuple/pgstatindex.c
View File

@ -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);

42
contrib/pgstattuple/pgstattuple.c
View File

@ -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);
}
}