From 75df6dc083f7a989697b5002a421fb204f2eeddb Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Sun, 18 Jan 2015 17:04:11 -0500 Subject: [PATCH] Fix ancient thinko in default table rowcount estimation. The code used sizeof(ItemPointerData) where sizeof(ItemIdData) is correct, since we're trying to account for a tuple's line pointer. Spotted by Tomonari Katsumata (bug #12584). Although this mistake is of very long standing, no back-patch, since it's a relatively harmless error and changing it would risk changing default planner behavior in stable branches. (I don't see any change in regression test outputs here, but the buildfarm may think differently.) --- src/backend/optimizer/util/plancat.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c index 265c865fcb..fb7db6d959 100644 --- a/src/backend/optimizer/util/plancat.c +++ b/src/backend/optimizer/util/plancat.c @@ -509,7 +509,7 @@ estimate_rel_size(Relation rel, int32 *attr_widths, tuple_width = get_rel_data_width(rel, attr_widths); tuple_width += sizeof(HeapTupleHeaderData); - tuple_width += sizeof(ItemPointerData); + tuple_width += sizeof(ItemIdData); /* note: integer division is intentional here */ density = (BLCKSZ - SizeOfPageHeaderData) / tuple_width; }