From: Tomasz Myrta <jasiek@klaster.net>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Lista dyskusyjna pgsql-sql <pgsql-sql@postgresql.org>
Subject: Re: cursors in plpgsql
Date: Thu, 18 Sep 2003 08:04:54 +0200
Message-ID: <3F694B06.3050802@klaster.net> (raw)
In-Reply-To: <5920.1063833193@sss.pgh.pa.us>
References: <3F68C810.6020401@klaster.net>
<5920.1063833193@sss.pgh.pa.us>
> Releases before 7.4 are spotty about supporting backwards scan of
> complex queries --- if you have a join or aggregate in the query,
> it likely won't work, yielding either strange errors or wrong answers.
>
> It will work if the top plan node in the query is a SORT, though, so
> a possible workaround is to add an explicit ORDER BY to the cursor's
> query. (You will need to do some investigation with EXPLAIN to make
> sure you are getting a suitable plan for the cursor.)
I rewrote my query to have sort in top of plan:
Sort (cost=151.24..151.25 rows=1 width=36)
Sort Key: czas
-> Aggregate (cost=151.22..151.23 rows=1 width=36)
-> Group (cost=151.22..151.23 rows=1 width=36)
-> Sort (cost=151.22..151.22 rows=1 width=36)
I'm not sure if it is what you were talking about, but it didn't help.
Anyway the best choice for this function would be a C function, but SPI
scares me...
And one more question - which syntax is valid?
move backward..
or
execute ''move backward...
> Or try 7.4 beta ...
Currently stable branches are better for me...
>
> regards, tom lane
Regards,
Tomasz Myrta
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To: pgsql-sql@postgresql.org
Cc: jasiek@klaster.net, tgl@sss.pgh.pa.us
Subject: Re: cursors in plpgsql
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