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

Jaime Casanova, reviewed by Noah Misch, slightly modified by me.

diff --git a/contrib/pgstattuple/pgstatindex.c b/contrib/pgstattuple/pgstatindex.c
index beff1b9855baefb770e8109aa51de45420dc6a37..9f2ec1f210840a45852a8b3dbd7d9892c3b1c4c8 100644 (file)
--- 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 7af724f24bb1dbb9ea732688428986dae6928008..c9be8c92e4bf2aecdd53e2e60683cb9a8cd5b524 100644 (file)
--- 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);
                }
        }