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Re: correct behavior of ANALYZE ...

From: Hans-Juergen Schoenig <postgres(at)cybertec(dot)at>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: correct behavior of ANALYZE ...
Date: 2007-08-30 08:28:37
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Lists: pgsql-hackers
hi tom ...

the idea behind this is to disable the stats on a certain column  
this would give me more control about the plan. in this special case  
data is changing so frequently that the default values are ways  
better than trying to keep the "real" stats up to date.
in case of default value i know what the DB does given a certain  
where clause - this is beyond my control when stats drop in.
i guess there are corner cases where no stats on certain fields can  
definitely help to make plans a little bit more stable.

	many thanks,


On Aug 29, 2007, at 6:44 PM, Tom Lane wrote:

> Hans-Juergen Schoenig <postgres(at)cybertec(dot)at> writes:
>> i came across some interesting behavior of pg_stats and i am not sure
>> if this is something we should treat the way we do it.
> Setting target zero means "expend no work on this column".  In my book
> that includes not doing anything to any pre-existing pg_stats entry.
> What you propose would defeat the ability to analyze an unchanging
> column once and then make ANALYZE skip over it henceforth.
> 			regards, tom lane
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