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Re: suggestion: set default statistics to 100 for numerics

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
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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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