2010/1/28 Pavel Stehule <pavel.steh...@gmail.com>: > 2010/1/28 David E. Wheeler <da...@kineticode.com>: >> On Jan 27, 2010, at 6:47 PM, Takahiro Itagaki wrote: >> >>> * I think we cannot cache the delimiter at the first call. >>> For example, >>> SELECT string_agg(elem, delim) >>> FROM (VALUES('A', ','), ('B', '+'), ('C', '*')) t(elem, delim); >>> should return 'A+B*C' rather than 'A,B,C'. >> >> Ooh, nice. >> >>> * Can we use StringInfo directly as the aggregate context instead of >>> StringAggState? For the first reason, we need to drop 'delimiter' field >>> from struct StringAggState. Now it has only StringInfo field. >> >> Makes sense. > > no, has not.
What is use case for this behave?? Pavel > > Pavel > >> >>> * We'd better avoiding to call text_to_cstring() for delimitors and elements >>> for performance reason. We can use appendBinaryStringInfo() here. >>> >>> My proposal patch attached. >>> >>> Also, I've not changed it yet, but it might be considerable: >>> >>> * Do we need better names for string_agg1_transfn and string_agg2_transfn? >>> They are almost "internal names", but we could have more >>> like string_agg_with_sep_transfn. >> >> Yes please. >> >>> Comments? >> >> Patch looks great, thank you! >> >> David >> >> >> > -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers