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);
        }
    }