Christopher Browne <[EMAIL PROTECTED]> writes:
> The "right answer" for most use seems likely to involve:
>  a) Getting an appropriate number of bins (I suspect 10 is a bit
>     small, but I can't justify that mathematically), and

I suspect that also, but I don't have real evidence for it either.
We've heard complaints from a number of people for whom it was indeed
too small ... but that doesn't prove it's not appropriate in the
majority of cases ...

> Does the sample size change if you increase the number of bins?

Yes, read the comments in backend/commands/analyze.c.

> Do we also need a parameter to control sample size?

Not if the paper I read before writing that code is correct.

                        regards, tom lane

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TIP 9: the planner will ignore your desire to choose an index scan if your
      joining column's datatypes do not match

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