Manfred Koizar <[EMAIL PROTECTED]> writes:
> On Fri, 28 Jan 2005 10:53:33 -0500, Tom Lane <[EMAIL PROTECTED]> wrote:
>> we should consider
>> something like "clamp to size of table / 10" instead.
> ... unless a *single* grouping column is estimated to have more than
> N/10 distinct values, which should be easy to check.
Already done that way.
/*
* Clamp to size of rel, or size of rel / 10 if multiple Vars.
* The fudge factor is because the Vars are probably correlated
* but we don't know by how much.
*/
double clamp = rel->tuples;
if (relvarcount > 1)
clamp *= 0.1;
if (reldistinct > clamp)
reldistinct = clamp;
regards, tom lane
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