On Thu, Sep 1, 2011 at 4:32 AM, Rik Bellens <rik.bellens@xxxxxxxxxxxxxx> wrote: > > Hello, > > I have two large tables in a database, one containing original data and the > other one derived from the first table. The first table contains several > columns and indexes, while the second table has less columns and only one > index. Both tables have the same number of rows. Nevertheless, the second > table is much larger in disk size than the first one. How can this be > explained? This is most likely due to table bloat. In PostgreSQL when you update or delete a row, a dead version gets left behind. Vacuum eventually comes along and reclaims the empty space to be reused. If you delete / update a LOT of rows at once, then you'll have a lot of dead rows which can only be reused after vacuuming when you do more updates or deletes later on. A few salient questions. What version of PostgreSQL are you running? Is autovacuum running? Do you do a LOT of bulk deletes / updates? If you do a lot of bulk deletes on this table, and you delete everything, can you switch to using the truncate command instead? -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
