Jeff Janes <jeff.janes@gmail.com> writes:
> I am getting corrupted Bloom indexes in which a tuple in the table
> heap is not in the index.
Hmm. I can trivially reproduce a problem, but I'm not entirely sure
whether it matches yours. Same basic test case as the bloom regression
test:
regression=# CREATE TABLE tst ( i int4, t text
);
CREATE TABLE
regression=# CREATE INDEX bloomidx ON tst USING bloom (i, t) WITH (col1 = 3);
CREATE INDEX
regression=# INSERT INTO tst SELECT i%10, substr(md5(i::text), 1, 1) FROM generate_series(1,2000) i;
INSERT 0 2000
regression=# vacuum verbose tst;
...
INFO: index "bloomidx" now contains 2000 row versions in 5 pages
...
regression=# delete from tst;
DELETE 2000
regression=# vacuum verbose tst;
...
INFO: index "bloomidx" now contains 0 row versions in 5 pages
DETAIL: 2000 index row versions were removed.
...
regression=# INSERT INTO tst SELECT i%10, substr(md5(i::text), 1, 1) FROM generate_series(1,2000) i;
INSERT 0 2000
regression=# vacuum verbose tst;
...
INFO: index "bloomidx" now contains 1490 row versions in 5 pages
...
Ooops. (Note: this is done with some fixes already in place to make
blvacuum.c return correct tuple counts for VACUUM VERBOSE; right now
it tends to double-count during a VACUUM.)
The problem seems to be that (1) blvacuum marks all the index pages as
BLOOM_DELETED, but doesn't bother to clear the notFullPage array on the
metapage; (2) blinsert uses a page from notFullPage, failing to notice
that it's inserting data into a BLOOM_DELETED page; (3) once we ask the
FSM for a page, it returns a BLOOM_DELETED page that we've already put
tuples into, which we happily blow away by reinit'ing the page.
A race-condition variant of this could be that after an autovacuum
has marked a page BLOOM_DELETED, but before it's reached the point of
updating the metapage, blinsert could stick data into the deleted page.
That would make it possible to reach the problem without requiring the
extreme edge case that blvacuum finds no partly-full pages to put into the
metapage. If this does explain your problem, it's probably that variant.
Will push a fix in a bit.
regards, tom lane
