postgres.git / summary / log / commit / refs

commit    75df6dc083f7a989697b5002a421fb204f2eeddb
Author:   Tom Lane <tgl@sss.pgh.pa.us>
Date:     Sun Jan 18 22:04:11 2015 +0000
First released in: 9.5.0

    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 265c865fcb8..fb7db6d9599 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;
 			}


[parent: 4c34dcf97f70]