On Tue, Jun 1, 2010 at 8:59 AM, Matthew Wakeling <matthew@xxxxxxxxxxx> wrote: > On Tue, 1 Jun 2010, Stephen Frost wrote: >> >> * Matthew Wakeling (matthew@xxxxxxxxxxx) wrote: >>> >>> The major case I found when writing pl/pgsql was when trying to build >>> arrays row by row. AFAIK when I tried it, adding a row to an array caused >>> the whole array to be copied, which put a bit of a damper on performance. >> >> Using the built-ins now available in 8.4 (array_agg), that copying >> doesn't happen any more. > > Thanks. I had wondered if that had been improved. even better is array(query) -- which has been around for a while. not too many people know about it because it's syntactically weird but it's the preferred way to build arrays when you don't need true aggregation (group by and such). generally speaking, concatenation of any kind in loops should be avoided in pl/pgsql. in fact, whenever writing pl/pgsql, it's all to easy to over-use the loop construct...every time you're looping it's always good to ask yourself: 'can this be done in a query?'. merlin -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
