From: | Joseph Shraibman <jks(at)selectacast(dot)net> |
---|---|
To: | Alvaro Herrera <alvherre(at)dcc(dot)uchile(dot)cl> |
Subject: | Re: suggestion: set default statistics to 100 for numerics |
Date: | 2004-07-01 23:30:25 |
Message-ID: | 40E49E91.2050201@selectacast.net |
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Lists: | pgsql-hackers |
Alvaro Herrera wrote:
> On Wed, Jun 30, 2004 at 10:56:53PM -0400, Joseph Shraibman wrote:
>
>>Seeing how small storage for a number type is compared to a text type,
>>and seeing how they tend to be queried on a lot, shouldn't it be
>>reasonable for the default stats number for numerics to be 100 instead
>>of 10?
>
>
> The problem is not only storage space, but also the optimizer runtime;
> which would have to munge the larger amount of data ... not sure if this
> is critical but enlarging it by default for all numeric columns may not
> be desirable.
I don't think the optimizer run time is that much longer in absolute
terms. The only reason I suggest it is that even experienced postgres
users probably don't think about this often enough
>
> Anyway ISTM a better rule would be enlarging the default stats number
> for columns that are part of an index, rather than using the datatype.
>
That has merit too, but I think text fields are queried on and indexed
less and would take up much more room in the stats table.
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