Fix tuple counting in SP-GiST index build.

tglsfdc · tglsfdc · commit 7f6f8ccd976d · 2018-03-22T13:23:48.000-04:00
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
@@ -30,6 +30,7 @@
 typedef struct
 {
 	SpGistState spgstate;		/* SPGiST's working state */
+	int64		indtuples;		/* total number of tuples indexed */
 	MemoryContext tmpCtx;		/* per-tuple temporary context */
 } SpGistBuildState;
 
@@ -57,6 +58,9 @@ spgistBuildCallback(Relation index, HeapTuple htup, Datum *values,
 		MemoryContextReset(buildstate->tmpCtx);
 	}
 
+	/* Update total tuple count */
+	buildstate->indtuples += 1;
+
 	MemoryContextSwitchTo(oldCtx);
 	MemoryContextReset(buildstate->tmpCtx);
 }
@@ -130,6 +134,7 @@ spgbuild(PG_FUNCTION_ARGS)
 	 */
 	initSpGistState(&buildstate.spgstate, index);
 	buildstate.spgstate.isBuild = true;
+	buildstate.indtuples = 0;
 
 	buildstate.tmpCtx = AllocSetContextCreate(CurrentMemoryContext,
 										   "SP-GiST build temporary context",
@@ -145,7 +150,8 @@ spgbuild(PG_FUNCTION_ARGS)
 	SpGistUpdateMetaPage(index);
 
 	result = (IndexBuildResult *) palloc0(sizeof(IndexBuildResult));
-	result->heap_tuples = result->index_tuples = reltuples;
+	result->heap_tuples = reltuples;
+	result->index_tuples = buildstate.indtuples;
 
 	PG_RETURN_POINTER(result);
 }
