>> with statistics without statistics >> case1 0.98 0.01 >> case2 98/0 1/0 > > The case2 shows that functional dependencies assume that the > conditions used in queries won't be incompatible - that's something > this type of statistics can't fix.
It would be nice if that's mentioned in the manual to avoid user's confusion. >> case3 1.05 0.01 >> case4 1/0 103/0 >> case5 18.50 18.33 >> case6 111123/0 1111123/0 > > The last two lines (case5 + case6) seem a bit suspicious. I believe > those are for the histogram data, and I do get these numbers: > > case5 0.93 (5517 / 5949) 42.0 (249943 / 5949) > case6 100/0 100/0 > > Perhaps you've been using the version before the bugfix, with ANALYZE > on the wrong table? You are right. I accidentally ANALYZE t2, not t3. Now I get these numbers: case5 1.23 (7367 / 5968) 41.7 (249118 / 5981) case6 117/0 162092/0 >> 2) following comments by me are not addressed in the v18 patch. >> >>> - There's no docs for pg_mv_statistic (should be added to "49. System >>> Catalogs") >>> >>> - The word "multivariate statistics" or something like that should >>> appear in the index. >>> >>> - There are some explanation how to deal with multivariate statistics >>> in "14.1 Using Explain" and "14.2 Statistics used by the Planner" >>> section. > > Yes, those are valid omissions. I plan to address them, and I'd also > considering adding a section to 65.1 (How the Planner Uses > Statistics), explaining more thoroughly how the planner uses > multivariate stats. Great. Best regards, -- Tatsuo Ishii SRA OSS, Inc. Japan English: http://www.sraoss.co.jp/index_en.php Japanese:http://www.sraoss.co.jp -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
