On fim, 2006-02-16 at 09:12 -0500, Emi Lu wrote: > Hello, > > We have a daily cronjob and in the cronjob we do: > 1. truncate one table A > 2. insert into table A > 3. do comparision table A and table B and update table B accordingly > > The doc says "VACUUM ANALYZE command for the affected table. This will > update the system catalogs with the results of all recent changes, and > allow the PostgreSQL query planner to make better choices in planning > queries". > So, I believe after insertion at step 2, comparision will be speed up if > we do a "vacuum analyze" right? after only truncate and inserts , vacuum is not needed, but ANALYZE is good. > In another way, whenever we "delete/truncate and then insert" data into > a table, it is better to "vacuum anaylze"? after deleting or updating a significant percentage of rows, VACUUM can be called for, but usually VACUUM is done as part of regular maintenance, or by autovacuum. gnari
