Fix tuple counting in SP-GiST index build.

Count the number of tuples in the index honestly, instead of assuming
that it's the same as the number of tuples in the heap.  (It might be
different if the index is partial.)

Back-patch to all supported versions.

Tomas Vondra

Discussion: https://postgr.es/m/3b3d8eac-c709-0d25-088e-b98339a1b28a@2ndquadrant.com

diff --git a/src/backend/access/spgist/spginsert.c b/src/backend/access/spgist/spginsert.c
index 34d9b48f15e45bce917cb97d7fe680b90daab7c4..7dd0d61fbbca6365dae442c4978555574368d712 100644 (file)
--- a/src/backend/access/spgist/spginsert.c
+++ b/src/backend/access/spgist/spginsert.c
@@ -32,6 +32,7 @@
 typedef struct
 {
        SpGistState spgstate;           /* SPGiST's working state */
+       int64           indtuples;              /* total number of tuples indexed */
        MemoryContext tmpCtx;           /* per-tuple temporary context */
 } SpGistBuildState;
 
@@ -59,6 +60,9 @@ spgistBuildCallback(Relation index, HeapTuple htup, Datum *values,
                MemoryContextReset(buildstate->tmpCtx);
        }
 
+       /* Update total tuple count */
+       buildstate->indtuples += 1;
+
        MemoryContextSwitchTo(oldCtx);
        MemoryContextReset(buildstate->tmpCtx);
 }
@@ -132,6 +136,7 @@ spgbuild(Relation heap, Relation index, IndexInfo *indexInfo)
         */
        initSpGistState(&buildstate.spgstate, index);
        buildstate.spgstate.isBuild = true;
+       buildstate.indtuples = 0;
 
        buildstate.tmpCtx = AllocSetContextCreate(CurrentMemoryContext,
                                                                                          "SP-GiST build temporary context",
@@ -146,7 +151,8 @@ spgbuild(Relation heap, Relation index, IndexInfo *indexInfo)
        SpGistUpdateMetaPage(index);
 
        result = (IndexBuildResult *) palloc0(sizeof(IndexBuildResult));
-       result->heap_tuples = result->index_tuples = reltuples;
+       result->heap_tuples = reltuples;
+       result->index_tuples = buildstate.indtuples;
 
        return result;
 }