Re: [SQL] Removing a constraint?
Michael Davis wrote: > Does anyone know how to completely and accurately remove or drop a > constraint, specifically a foreign key constraint? I tried to remove a > constraint by deleting it's trigger from pg_triggers. This caused some > undesirable side effects with other tables involved with the constraint. I > have several tables that I need to change the column constraints and > foreign key constraints on. Recreating (drop and create) the table every > time I need to change a column constraint is a pain because all the objects > that reference the table would also need to be recreated (i.e. views and > triggers). How do production DBAs successfully make changes to their > tables? > > FYI, I was able to alter table add the same constraint many times. Is this > a problem? This created a new trigger in pg_triggers every time. A bug in "cluster" will do this, if you cluster a table it will drop all constraints and indexes. One could use pg_dump, as: pg_dump -a -t table database > table_data.sql pg_dump -s -t table database > table_schema.sql (edit table_schema.sql to remove constraint) psql database < table_schema.sql psql database < table_data.sql
Re: [SQL] Index of a table is not used (in any case)
Doug McNaught wrote: > Reiner Dassing <[EMAIL PROTECTED]> writes: > > > Hello PostgreSQl Users! > > > > PostSQL V 7.1.1: > > > > I have defined a table and the necessary indices. > > But the index is not used in every SELECT. (Therefore, the selects are > > *very* slow, due to seq scan on > > 20 million entries, which is a test setup up to now) > > Perennial first question: did you VACUUM ANALYZE? Can there, or could there, be a notion of "rule based" optimization of queries in PostgreSQL? The "not using index" problem is probably the most common and most misunderstood problem. ---(end of broadcast)--- TIP 3: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly
