Re: 8.4 optimization regression?

I wrote:
> Mark Kirkwood <mark(dot)kirkwood(at)catalyst(dot)net(dot)nz> writes:
>> [ assorted examples showing that commit
>> 7f3eba30c9d622d1981b1368f2d79ba0999cdff2 has got problems ]

> ...
> So, not only are you correct that we should revert the changes to
> eqjoinsel_inner, but what's happening in eqjoinsel_semi is wrong too.

I've retested these examples with the patches I committed yesterday.
Six of the eight examples are estimated pretty nearly dead on, while the
other two are estimated about 50% too high (still a lot better than
before). AFAICT there's no easy way to improve those estimates further;
eqjoinsel_semi just plain hasn't got enough information to know how many
matches there will be.

regards, tom lane