Re: suggestion: set default statistics to 100 for numerics
Joseph Shraibman <jks@selectacast.net>
From: Joseph Shraibman <jks@selectacast.net>
To: Alvaro Herrera <alvherre@dcc.uchile.cl>
Date: 2004-07-01T23:30:25Z
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.