On Thu, 15 Jan 2026 at 13:35, Kirill Reshke <[email protected]> wrote: > > On Thu, 15 Jan 2026 at 13:21, Kirill Reshke <[email protected]> wrote: > > > > On Thu, 15 Jan 2026 at 12:46, Kirill Reshke <[email protected]> wrote: > > > > > > On Thu, 15 Jan 2026 at 12:00, Kirill Reshke <[email protected]> > > > wrote: > > > > > > > > Hi hackers. > > > > > > > > While looking at [0] I noticed that XLOG_GIST_DELETE & > > > > XLOG_GIST_PAGE_DELETE > > > > records are not covered. > > > > > > > > This thread addresses XLOG_GIST_DELETE, which is also known as a > > > > microvacuum feature. > > > > > > > > test.sql contains regression test that trigger this code to be > > > > exercised in stream_regress.pl TAP test. > > > > > > > > Test is as follows: we create a gist index on the table, then we > > > > insert exactly 407 records, making the root page full (next insert > > > > will trigger page split). Then I delete all tuples from relation and > > > > trigger Index Only scan to do kill-on-select (killtuples). It marks > > > > gist 0 page (which is root and is leaf) as has_garbage. Then, the next > > > > insertion triggers xlog_gist_delete record. > > > > > > > > To verify this I use pageinspect and pg_waldimp (locally). Also this > > > > test is dependent on block size being 8192 which is not good. > > > > > > > > > > > > And all of this does not work actually without v1-0001, because there > > > > is a bug in GiST which does not call gistkillitmes for the very first > > > > (root) page. > > > > > > > > There is also test2.sql which inserts a single tuple, not 407. It can > > > > be used to verify v1-0001. > > > > > > > > [0] coverage.postgresql.org/src/backend/access/gist/gistxlog.c.gcov.html > > > > > > > > > > > > -- > > > > Best regards, > > > > Kirill Reshke > > > > > > > > > From cf feedback it turns out we already have an isolation test for > > > this, and it does almost exactly the same. > > > And more, it fails. > > > Will try to fix > > > > > > > > > -- > > > Best regards, > > > Kirill Reshke > > > > This looks like gist does not work for small indexes and this is > > explicitly tested after [0] > > [0] > > https://www.postgresql.org/message-id/lxzj26ga6ippdeunz6kuncectr5gfuugmm2ry22qu6hcx6oid6%40lzx3sjsqhmt6 > > > > > > -- > > Best regards, > > Kirill Reshke > > I was right on commit message of 377b7ab > > """ > For gist some related paths were reached, but gist's implementation > seems to not work if all the dead tuples are on one page (or something > like that). The coverage for other index types was rather incidental. > """ > > It does not work if all the dead tuples are on one page and this page is > ROOT. > > So, should we delete this > > ... > # Test gist, but with fewer rows - shows that killitems doesn't work anymore! > permutation > create_table fill_10 create_ext_btree_gist create_gist flush > disable_seq disable_bitmap > > ... > > from isolation spec? > > > -- > Best regards, > Kirill Reshke
PFA v2 which leaves the test in-place. Also commit message improvements. -- Best regards, Kirill Reshke
v2-0001-Fix-gistkillitems-for-GiST-ROOT-page.patch
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