Prevent synchronous scan during GIN index build, because GIN is optimized

for inserting tuples in increasing TID order.  It's not clear whether this
fully explains Ivan Sergio Borgonovo's complaint, but simple testing
confirms that a scan that doesn't start at block 0 can slow GIN build by
a factor of three or four.

Backpatch to 8.3.  Sync scan didn't exist before that.

diff --git a/src/backend/access/gin/gininsert.c b/src/backend/access/gin/gininsert.c
index 1942da1a45d022693bc6d51c216a2fd7b14701c8..dd805c9f8f890d27cb7c6d09e6d72b1b32a36e7e 100644 (file)
--- a/src/backend/access/gin/gininsert.c
+++ b/src/backend/access/gin/gininsert.c
@@ -340,8 +340,11 @@ ginbuild(PG_FUNCTION_ARGS)
        buildstate.accum.ginstate = &buildstate.ginstate;
        ginInitBA(&buildstate.accum);
 
-       /* do the heap scan */
-       reltuples = IndexBuildHeapScan(heap, index, indexInfo,
+       /*
+        * Do the heap scan.  We disallow sync scan here because dataPlaceToPage
+        * prefers to receive tuples in TID order.
+        */
+       reltuples = IndexBuildHeapScan(heap, index, indexInfo, false,
                                                                   ginBuildCallback, (void *) &buildstate);
 
        /* dump remaining entries to the index */

diff --git a/src/backend/access/gist/gist.c b/src/backend/access/gist/gist.c
index 9a53941715ea28013cc13291b941d5f9b9037480..58050803be332f9eff0d306007720f7d931f4f31 100644 (file)
--- a/src/backend/access/gist/gist.c
+++ b/src/backend/access/gist/gist.c
@@ -152,7 +152,7 @@ gistbuild(PG_FUNCTION_ARGS)
        buildstate.tmpCtx = createTempGistContext();
 
        /* do the heap scan */
-       reltuples = IndexBuildHeapScan(heap, index, indexInfo,
+       reltuples = IndexBuildHeapScan(heap, index, indexInfo, true,
                                                                   gistbuildCallback, (void *) &buildstate);
 
        /* okay, all heap tuples are indexed */

diff --git a/src/backend/access/hash/hash.c b/src/backend/access/hash/hash.c
index 84e6617aab8cf7443eefbcc0028a27050e81c8d3..c2c2759fc88a8d2bcbb80cfa300b2283ae68ff6f 100644 (file)
--- a/src/backend/access/hash/hash.c
+++ b/src/backend/access/hash/hash.c
@@ -93,7 +93,7 @@ hashbuild(PG_FUNCTION_ARGS)
        buildstate.indtuples = 0;
 
        /* do the heap scan */
-       reltuples = IndexBuildHeapScan(heap, index, indexInfo,
+       reltuples = IndexBuildHeapScan(heap, index, indexInfo, true,
                                                                   hashbuildCallback, (void *) &buildstate);
 
        if (buildstate.spool)

diff --git a/src/backend/access/nbtree/nbtree.c b/src/backend/access/nbtree/nbtree.c
index 366da36517f4cf4e4167185fae9298f114cf480a..825ff5c6a217d7251655a8746e42e0aaf9d6ff85 100644 (file)
--- a/src/backend/access/nbtree/nbtree.c
+++ b/src/backend/access/nbtree/nbtree.c
@@ -122,7 +122,7 @@ btbuild(PG_FUNCTION_ARGS)
                buildstate.spool2 = _bt_spoolinit(index, false, true);
 
        /* do the heap scan */
-       reltuples = IndexBuildHeapScan(heap, index, indexInfo,
+       reltuples = IndexBuildHeapScan(heap, index, indexInfo, true,
                                                                   btbuildCallback, (void *) &buildstate);
 
        /* okay, all heap tuples are indexed */

diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c
index 65da5239a990a79063aa0e12844cdd404852922d..90c07b6b0b25f8e01ce281edef78145ae3d042e8 100644 (file)
--- a/src/backend/catalog/index.c
+++ b/src/backend/catalog/index.c
@@ -1513,6 +1513,7 @@ double
 IndexBuildHeapScan(Relation heapRelation,
                                   Relation indexRelation,
                                   IndexInfo *indexInfo,
+                                  bool allow_sync,
                                   IndexBuildCallback callback,
                                   void *callback_state)
 {
@@ -1575,7 +1576,12 @@ IndexBuildHeapScan(Relation heapRelation,
                OldestXmin = GetOldestXmin(heapRelation->rd_rel->relisshared, true);
        }
 
-       scan = heap_beginscan(heapRelation, snapshot, 0, NULL);
+       scan = heap_beginscan_strat(heapRelation,       /* relation */
+                                                               snapshot,               /* snapshot */
+                                                               0,                              /* number of keys */
+                                                               NULL,                   /* scan key */
+                                                               true,                   /* buffer access strategy OK */
+                                                               allow_sync);    /* syncscan OK? */
 
        reltuples = 0;
 

diff --git a/src/include/catalog/index.h b/src/include/catalog/index.h
index b18ccb3bea6530999e84e12ee6c76975baf06993..322f1a991c852afd8b7d81a5cce0bc2065b173ce 100644 (file)
--- a/src/include/catalog/index.h
+++ b/src/include/catalog/index.h
@@ -63,6 +63,7 @@ extern void index_build(Relation heapRelation,
 extern double IndexBuildHeapScan(Relation heapRelation,
                                   Relation indexRelation,
                                   IndexInfo *indexInfo,
+                                  bool allow_sync,
                                   IndexBuildCallback callback,
                                   void *callback_state);