2010/11/18 Cédric Villemain <cedric.villemain.deb...@gmail.com>: > 2010/11/18 Robert Haas <robertmh...@gmail.com>: >> On Thu, Nov 18, 2010 at 10:24 AM, Merlin Moncure <mmonc...@gmail.com> wrote: >>> On Thu, Nov 18, 2010 at 12:47 AM, Tom Lane <t...@sss.pgh.pa.us> wrote: >>>> Merlin Moncure <mmonc...@gmail.com> writes: >>>>> On Wed, Nov 17, 2010 at 7:08 PM, Jaime Casanova <ja...@2ndquadrant.com> >>>>> wrote: >>>>>> i will start the review of this one... but before that sorry for >>>>>> suggesting this a bit later but about using UNNEST as part of the >>>>>> sintax? >>>> >>>>> Does for-in-array do what unnset does? >>>> >>>> Yes, which begs the question of why bother at all. AFAICS this patch >>>> simply allows you to replace >>>> >>>> for x in select unnest(array_value) loop >>>> >>>> with >>>> >>>> for x in unnest array_value loop >>>> >>>> (plus or minus a parenthesis or so). I do not think we need to add a >>>> bunch of code and create even more syntactic ambiguity (FOR loops are >>>> already on the hairy edge of unparsability) to save people from writing >>>> "select". >>> >>> Pavel's performance argument is imnsho valid. arrays at present are >>> the best way to pass data around functions and any optimizations here >>> are very welcome. Given that, is there any way to mitigate your >>> concerns on the syntax side? >> >> Can we get the performance benefit any other way? I hate to think >> that it will still be slow for people using the already-supported >> syntax. > > If you are able to make unnest() outputting 1st row without detoasting > last field. > > I think if we have : > #define DatumGetTextPSlice(X,m,n) ((text *) PG_DETOAST_DATUM_SLICE(X,m,n)) > but for array, most is done > > Pavel, am I correct ?
yes, it can help, but still if you iterate over complete array, you have to do n - detoast ops. Pavel > >> >> -- >> Robert Haas >> EnterpriseDB: http://www.enterprisedb.com >> The Enterprise PostgreSQL Company >> >> -- >> Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) >> To make changes to your subscription: >> http://www.postgresql.org/mailpref/pgsql-hackers >> > > > > -- > Cédric Villemain 2ndQuadrant > http://2ndQuadrant.fr/ PostgreSQL : Expertise, Formation et Support > -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
