On Tue, 2005-08-02 at 17:32 +0300, Victor wrote: > Hello. > > I use psql (PostgreSQL) 7.4.5. > > I have a cost problem. > > A simple select lasts too long. > I have a table with aprox 900 rows. > All rows are deleted and reinserted once a minute. > > EXPLAIN ANALYZE SELECT * FROM logati; > QUERY PLAN > ----------------------------------------------------------------------------------------------------------------------- > Seq Scan on logati (cost=0.00..100741.22 rows=1198722 width=340) > (actual time=35927.945..35944.272 rows=842 loops=1) > Total runtime: 35945.840 ms The rows are not actually removed when DELETE happens. the next VACUUM vill put them into the Free Space Map if they are older than the oldest running transaction, so that their space can be reused. this means that you must VACUUM this table frequently to keep it from bloating. If the data distribution keeps changing , you should also ANALYZE frequently (but not when the table in empty), but that is another matter. to fix an already severely bloated table, you might need to do a VACUUM FULL on it once, but after that frequent-enough regular (non-FULL) VACUUMS should do. depending on the nature of your processes, you might want to use TRUNCATE to empty your table. gnari ---------------------------(end of broadcast)--------------------------- TIP 5: don't forget to increase your free space map settings
