If you need to remove large amounts of data from a table ( specially when you need to remove *all* the data in a table), remember its faster to drop the table, and recreate it rather than doing a 'delete from tablename;'.

eg: this is against a postgresql db:

drop table rawdata;

Response time: 0m 2s 433ms  Total time: 0m 2s 433ms

CREATE TABLE "rawdata" ("ip" char(33), "sdate" varchar(20) NOT NULL,
 "key" varchar(100) NOT NULL,"country" varchar(2), "region" varchar(2),
  "city" varchar(40), "machine" int);

Response time: 0m 0s 337ms  Total time: 0m 0s 337ms

Whereas:

delete from rawdata;
200000000 row(s) affected

Response time: 0m 15s 353ms  Total time: 0m 15s 353ms

In some cases, where you want to drop most ( eg > 80% ) of the data in the table, its faster to select the data to be retained into a temp table, drop the original table and rebuild the temp table to the original name.

- KB