October 8th, 2011 by depesz | Tags: covering, index, pg92, postgresql, scan, visibility, visibility maps | 12 comments »
On 8th of October, Tom Lane committed patch: Support index-only scans using the visibility map to avoid heap fetches. When a btree index contains all columns required by the query, and the visibility map shows that all tuples on a target heap page ...
December 8th, 2008 by depesz | Tags: pg84, postgresql, vacuum, visibility, visibility maps | 1 comment »
Yeah. This one patch alone is worth upgrading to 8.4. On 3rd of December Heikki Linnakangas committed his patch. Commit message: Introduce visibility map. The visibility map is a bitmap with one bit per heap page, where a set bit indicates that all ...
