Andrew Gierth <and...@tao11.riddles.org.uk> writes: > Hm. I am wrong about this, since it's the fact that consumers are taking > stanullfrac into account that makes the value wrong in the first place.
Also, the way that the value is calculated in the samples-not-all-distinct case corresponds to the way I have it in the patch. What you want to do would correspond to leaving these edge cases alone and changing all the other ANALYZE cases instead (*plus* changing the consumers). I find that a tad scary. > But I think the fix is still wrong, because it changes the meaning of > ALTER TABLE ... ALTER col SET (n_distinct=...) in a non-useful way; it > is no longer possible to nail down a useful negative n_distinct value if > the null fraction of the column is variable. I think that argument is bogus. If we change the way that get_variable_numdistinct (and other consumers) use the value, that will break all existing custom settings of n_distinct, because they will no longer mean what they did before. There have been exactly zero field complaints that people could not get the results they wanted, so I do not think that's justified. In short, what you want to do constitutes a redefinition of stadistinct, while my patch doesn't. That is far more invasive and I fear it will break things that are not broken today. regards, tom lane -- Sent via pgsql-hackers mailing list (firstname.lastname@example.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers