Re: BitmapHeapScan streaming read user and prelim refactoring
| От | Richard Guo |
|---|---|
| Тема | Re: BitmapHeapScan streaming read user and prelim refactoring |
| Дата | |
| Msg-id | CAMbWs48orzZVXa7-vP9Nt7vQWLTE04Qy4PePaLQYsVNQgo6qRg@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: BitmapHeapScan streaming read user and prelim refactoring (Tomas Vondra <tomas.vondra@enterprisedb.com>) |
| Список | pgsql-hackers |
On Sun, Apr 7, 2024 at 10:42 PM Tomas Vondra <tomas.vondra@enterprisedb.com> wrote:
create table t (a int, b int) with (fillfactor=10);
insert into t select mod((i/22),2), (i/22) from generate_series(0,1000)
S(i);
create index on t(a);
vacuum analyze t;
set enable_indexonlyscan = off;
set enable_seqscan = off;
explain (analyze, verbose) select 1 from (values (1)) s(x) where exists
(select * from t where a = x);
KABOOM!
FWIW, it seems to me that this assert could be triggered in cases where,
during a join, not all inner tuples need to be scanned before skipping to
next outer tuple. This can happen for 'single_match' or anti-join.
The query provided by Tomas is an example of 'single_match' case. Here
is a query for anti-join that can also trigger this assert.
explain (analyze, verbose)
select t1.a from t t1 left join t t2 on t2.a = 1 where t2.a is null;
server closed the connection unexpectedly
Thanks
Richard
during a join, not all inner tuples need to be scanned before skipping to
next outer tuple. This can happen for 'single_match' or anti-join.
The query provided by Tomas is an example of 'single_match' case. Here
is a query for anti-join that can also trigger this assert.
explain (analyze, verbose)
select t1.a from t t1 left join t t2 on t2.a = 1 where t2.a is null;
server closed the connection unexpectedly
Thanks
Richard
В списке pgsql-hackers по дате отправления: