Once more, thanks! Of course, using SERIAL is the ideal method, but I can't have the programs in question fail because someone neglected to set up a dependency. Other people may be slobs, but I'm afraid I can't be. In fact, my very first attempt to use pg_get_serial_sequence(table_name, column_name) returned a NULL result, which tells me that it's a reality I have to deal with.
I'll stick with the column default parsing method... Adrian, Jerry - thanks very much for the info. Carlo -----Original Message----- From: Adrian Klaver [mailto:adrian.kla...@gmail.com] Sent: March 31, 2011 6:15 PM To: Carlo Stonebanks Cc: pgsql-general@postgresql.org Subject: Re: [GENERAL] Sequence names have 64 character limit? On 03/31/2011 02:47 PM, Carlo Stonebanks wrote: > Thanks Adrian and Jerry. > > Technically, the best way to know which sequence a column is dependent on is > to actually query for it. I have functions which query > information_schema.columns and run a regex_replace to extract the sequence > name from the defaulting nextval() expression. This is better than demanding > that sequence names are predictable, but I wonder if there isn't a better > query to run that doesn't require parsing texts? Obviously PG knows about > the sequence's relation, probably via a dependency that finds it by > rendering the text to regclass to an OID... but this stuff makes me nervous. > > So, a query that returns the sequence name (as text, you can cast to > regclass!) associated with a particular column, that would return NUL if > there was none... I don't suppose anyone has written such a query before...? > > Yes, I'd write a function around it! > > Thanks again, > > Carlo Well in 8.2+ for sequences created by the SERIAL datatype there is the function: pg_get_serial_sequence(table_name, column_name) The benefit of using SERIAL is that it sets up a dependency. If you specify the sequence via CREATE SEQUENCE then AFAIK you are left looking up the default and parsing it. -- Adrian Klaver adrian.kla...@gmail.com -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
