On 3/15/22 13:26, Tomas Vondra wrote:
Thanks for the rebase. The two proposed changes (tweaked costing and
simplified fake_var handling) seem fine to me. I think the last thing
that needs to be done is cleanup of the debug GUCs, which I added to
allow easier experimentation with the patch.
Thanks, I'm waiting for the last step.
I probably won't remove the GUCs entirely, though. I plan to add a
single GUC that would enable/disable this optimization. I'm not a huge
fan of adding more and more GUCs, but in this case it's probably the
right thing to do given the complexity of estimating cost with
correlated columns etc.
Agree. Because it is a kind of automation we should allow user to switch
it off in the case of problems or manual tuning.
Also, I looked through this patch. It has some minor problems:
1. Multiple typos in the patch comment.
2. The term 'cardinality of a key' - may be replace with 'number of
duplicates'?
--
regards,
Andrey Lepikhov
Postgres Professional
