[HACKERS] Partial match fix for fast scan
Hi, GIN partial match appears to be broken after fast scan. Following simple test case raises assertion failure. create extension btree_gin; create table test as (select id, random() as val from generate_series(1,100) id); create index test_idx on test using gin (val); vacuum test; select * from test where val between 0.1 and 0.9; Attached patch fixes bugs in entryGetItem function. I would especially point that continue; checks while condition even if it's postfix while. That's why I surrounded tbm_iterate with another while. -- With best regards, Alexander Korotkov. ginfastscanfix.patch Description: Binary data -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
Re: [HACKERS] Partial match fix for fast scan
On Thu, Apr 10, 2014 at 11:09 AM, Alexander Korotkov aekorot...@gmail.comwrote: Hi, GIN partial match appears to be broken after fast scan. Following simple test case raises assertion failure. create extension btree_gin; create table test as (select id, random() as val from generate_series(1,100) id); create index test_idx on test using gin (val); vacuum test; select * from test where val between 0.1 and 0.9; Attached patch fixes bugs in entryGetItem function. I would especially point that continue; checks while condition even if it's postfix while. That's why I surrounded tbm_iterate with another while. Interesting... to me (using current master) your test case doesn't fail... fabrizio=# select * from test where val between 0.1 and 0.9; id |val +--- 1 | 0.554413774050772 2 | 0.767866868525743 3 | 0.601187175605446 ... But fail if I change the values of between clause: fabrizio=# select * from test where val between 0.1 and 0.19; ERROR: tuple offset out of range: 8080 Regards, -- Fabrízio de Royes Mello Consultoria/Coaching PostgreSQL Timbira: http://www.timbira.com.br Blog sobre TI: http://fabriziomello.blogspot.com Perfil Linkedin: http://br.linkedin.com/in/fabriziomello Twitter: http://twitter.com/fabriziomello
Re: [HACKERS] Partial match fix for fast scan
On Thu, Apr 10, 2014 at 8:22 PM, Fabrízio de Royes Mello fabriziome...@gmail.com wrote: On Thu, Apr 10, 2014 at 11:09 AM, Alexander Korotkov aekorot...@gmail.com wrote: Hi, GIN partial match appears to be broken after fast scan. Following simple test case raises assertion failure. create extension btree_gin; create table test as (select id, random() as val from generate_series(1,100) id); create index test_idx on test using gin (val); vacuum test; select * from test where val between 0.1 and 0.9; Attached patch fixes bugs in entryGetItem function. I would especially point that continue; checks while condition even if it's postfix while. That's why I surrounded tbm_iterate with another while. Interesting... to me (using current master) your test case doesn't fail... fabrizio=# select * from test where val between 0.1 and 0.9; id |val +--- 1 | 0.554413774050772 2 | 0.767866868525743 3 | 0.601187175605446 ... But fail if I change the values of between clause: fabrizio=# select * from test where val between 0.1 and 0.19; ERROR: tuple offset out of range: 8080 It must be compiled with --enable-cassert to fail on assertion. -- With best regards, Alexander Korotkov.
Re: [HACKERS] Partial match fix for fast scan
On 04/10/2014 10:00 PM, Alexander Korotkov wrote: On Thu, Apr 10, 2014 at 8:22 PM, Fabrízio de Royes Mello fabriziome...@gmail.com wrote: On Thu, Apr 10, 2014 at 11:09 AM, Alexander Korotkov aekorot...@gmail.com wrote: GIN partial match appears to be broken after fast scan. Following simple test case raises assertion failure. create extension btree_gin; create table test as (select id, random() as val from generate_series(1,100) id); create index test_idx on test using gin (val); vacuum test; select * from test where val between 0.1 and 0.9; Attached patch fixes bugs in entryGetItem function. I would especially point that continue; checks while condition even if it's postfix while. That's why I surrounded tbm_iterate with another while. Interesting... to me (using current master) your test case doesn't fail... fabrizio=# select * from test where val between 0.1 and 0.9; id |val +--- 1 | 0.554413774050772 2 | 0.767866868525743 3 | 0.601187175605446 ... But fail if I change the values of between clause: fabrizio=# select * from test where val between 0.1 and 0.19; ERROR: tuple offset out of range: 8080 It must be compiled with --enable-cassert to fail on assertion. I'm actually getting the tuple offset out of range with Fabrizio's query, even after your fix (not every time, run it a few times, launching a new connection each time). So there's another bug lurking there. The problem seems to be that even though we've checked in the innermost loop that not all of the items on the page are = advancePast, that situation can change later if advancePast is advanced. So on next invocation entryGetItem, the loop to skip past advancePast might read bogus offsets in the array. I pushed a patch, which includes Alexander's fix, and also fixes the second issue. - Heikki -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
