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Re: [COMMITTERS] pgsql/src/backend/nodes (copyfuncs.c outfuncs.c print.c)

From: Philip Warner <pjw(at)rhyme(dot)com(dot)au>
To: pgsql-hackers(at)postgresql(dot)org
Subject: Re: [COMMITTERS] pgsql/src/backend/nodes (copyfuncs.c outfuncs.c print.c)
Date: 2000-10-27 11:20:43
Message-ID: 3.0.5.32.20001027212043.02af7790@mail.rhyme.com.au (view raw or flat)
Thread:
Lists: pgsql-hackers
[To hackers this time]

At 12:11 27/10/00 +0900, Hiroshi Inoue wrote:
>
>For example,LIMIT ALL means LIMIT 1 for optimizer and means
>no LIMIT for executor.
>Comments ?
>

It seems there's two possibilities:

(a) You know you will only use a limited number of rows, but you are not
sure exactly how many. In this case, I'd vote for a 'OPTIMIZE FOR FAST
START' clause.

(b) You really want all rows, in which case you should let the optimizer do
it's stuff. If it fails to work well, then use either 'OPTIMIZE FOR TOTAL
COST' or 'OPTIMIZE FOR FAST START' to change the behaviour.

ISTM that LIMIT ALL is just the syntax for the default limit clause - and
should, if anything, be equivalent to 'OPTIMIZE FOR TOTAL COST'.


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Subject: Re: [COMMITTERS] pgsql/src/backend/nodes (copyfuncs.c outfuncs.c print.c)
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