07.01.2022 12:00, Alexander Lakhin wrote: > Hello, > 07.01.2022 09:26, Japin Li wrote: >> On Fri, 07 Jan 2022 at 03:21, Tom Lane <t...@sss.pgh.pa.us> wrote: >> >> In any case, if we do need same() to implement the identical >> behavior to bpchareq(), then the other solution isn't sufficient >> either. >> >> So in short, it seems like we ought to do some compatibility testing >> and see if this code misbehaves at all with an index created by the >> old code. I don't particularly want to do that ... any volunteers? >> >> Thanks for your patch, it looks good to me. I'm not sure how to test this. > I will test it tomorrow. I've made a simple test based on the regression test (see attachment) and can confirm that REINDEX after upgrade fixes the index contents.
Differences after upgrade but before REINDEX: --- /tmp/pgtest/char.out 2022-01-08 21:27:43.912274805 +0300 +++ /tmp/pgtest/char.expected 2022-01-08 21:27:43.896274765 +0300 @@ -40,8 +40,8 @@ (2 rows) SELECT * FROM chartmp WHERE a BETWEEN '31a' AND '31c'; - a ------- - 31b0 + a +---------------------------------- + 31b0 (1 row) REINDEX INDEX charidx Differences after upgrade and REINDEX: Files /tmp/pgtest/char.out and /tmp/pgtest/char.expected are identical (Unfortunately for me) I found no anomalies related to gbt_text_same() with an index created with the previous implementation. I've added diagnostic logging that shows when gbt_text_same() returns 0 for keys that are the equal but have different padding. So I've observed that gbt_text_same() returns incorrect result, but all the btree_gist tests still pass. Moreover, unconditional "*result = 0;" in gbt_text_same() doesn't affect the tests at all. I've found that gbt_text_same() is called by gistKeyIsEQ() from backend/access/gist/gistutil.c, and made gistKeyIsEQ() return false any time. And even with such change all check-world tests still pass (except for isolation/predicate-gist that failed due to locking of pages split differently). So for now, I still don't know how to get incorrect query results due to incorrect gistKeyIsEQ() behavior/excessive page splitting. Best regards, Alexander
btree_gist-bpchar-test.sh
Description: application/shellscript
