I think array_agg also keeps nulls - although the draft standard I have seems to contradict itself about this...
Ian 2008/10/26 Jeff Davis <[EMAIL PROTECTED]>: > Here is a patch to support two aggregate functions: > > 1) ARRAY_AGG() -- SQL 2008 standard behavior, returns NULL on no input, > and skips NULL inputs. > > 2) ARRAY_ACCUM() -- Returns empty array on no input, and includes NULL > inputs. > > These accumulate the result in a memory context that lives across calls > to the state function, so it's reasonably efficient. On my old laptop it > takes about 5s to generate an array of 1M elements -- not great, but at > least it's linear. > > Although array_agg is the standard behavior, array_accum is important > because otherwise you always lose the NULLs, and that's difficult to > work around even with COALESCE. > > I added them as new native functions because ARRAY_AGG is in the > standard, but if others think they should live elsewhere that's fine. I > think that they are generally pretty useful functions for people using > arrays. > > This patch is contributed by Truviso. > > Regards, > Jeff Davis > > > > -- > Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-hackers > > -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
