"Tom Lane" <[EMAIL PROTECTED]> writes: > "Pavan Deolasee" <[EMAIL PROTECTED]> writes: >> What if we just track the amount of potentially dead space in the >> relation >> (somebody had suggested that earlier in the thread) ? Every committed >> UPDATE/DELETE and aborted UPDATE/INSERT would increment >> the dead space. Whenever page fragmentation is repaired, either during >> normal operation or during vacuum, the dead space is reduced by the >> amount of reclaimed space. Autovacuum triggers whenever the percentage >> of dead space increases beyond a threshold. > > Doesn't this design completely fail to take index bloat into account? > Repairing heap fragmentation does not reduce the need for VACUUM to work > on the indexes.
Index bloat is a bit of an open issue already. Because page splits already prune any LP_DELETEd pointers any busy index keys will be pruned already. However any index keys which have not been the subject of an index lookup -- and that includes keys which are only accessed by bitmap-index-scans -- won't be pruned. So we don't really know how much bloat is currently in an index. Perhaps we need a new statistic which gets updated whenever a page split prunes LP_DELETEd pointers (or perhaps when LP_DELETE is set?). -- Gregory Stark EnterpriseDB http://www.enterprisedb.com ---------------------------(end of broadcast)--------------------------- TIP 7: You can help support the PostgreSQL project by donating at http://www.postgresql.org/about/donate
