Thread: suggestion: set default statistics to 100 for numerics

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?

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.

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.

-- 
Alvaro Herrera (<alvherre[a]dcc.uchile.cl>)
"Porque Kim no hacia nada, pero, eso sí,
con extraordinario éxito" ("Kim", Kipling)

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.