Re: [HACKERS] NOWAIT doesn't work
> Now, is this the right behavior? I'm not sure. But I know for certain > that making it behave as you expect is very tricky. The table lock is > grabbed during parse analysis; we'd have to postpone grabbing the lock > until after we have had the chance to notice that there's a FOR UPDATE > clause for the table with a NOWAIT option attached. I think our present behavior violates POLS. Users would logically expect NOWAIT to work for all types of locks. If we get LOCK TIMEOUT working in 9.3, this will apply there as well. No question that changing that would be a new feature, though. -- Josh Berkus PostgreSQL Experts Inc. http://pgexperts.com -- 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] NOWAIT doesn't work
2012/10/31 Alvaro Herrera : > Alvaro Herrera escribió: > >> Now, is this the right behavior? I'm not sure. But I know for certain >> that making it behave as you expect is very tricky. The table lock is >> grabbed during parse analysis; we'd have to postpone grabbing the lock >> until after we have had the chance to notice that there's a FOR UPDATE >> clause for the table with a NOWAIT option attached. > > Furthermore you could do it manually: just do a LOCK TABLE NOWAIT in the > second session before the SELECT FOR UPDATE. I understand now, thank you to all for information Regards Pavel > > -- > Álvaro Herrerahttp://www.2ndQuadrant.com/ > PostgreSQL Development, 24x7 Support, Training & Services -- 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] NOWAIT doesn't work
Alvaro Herrera escribió: > Now, is this the right behavior? I'm not sure. But I know for certain > that making it behave as you expect is very tricky. The table lock is > grabbed during parse analysis; we'd have to postpone grabbing the lock > until after we have had the chance to notice that there's a FOR UPDATE > clause for the table with a NOWAIT option attached. Furthermore you could do it manually: just do a LOCK TABLE NOWAIT in the second session before the SELECT FOR UPDATE. -- Álvaro Herrerahttp://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- 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] NOWAIT doesn't work
Pavel Stehule escribió: > Hello > > it is expected behave? > > 1.session > > postgres=# begin; > BEGIN > postgres=# lock oo IN ACCESS EXCLUSIVE MODE; > LOCK TABLE > > 2. session > > postgres=# select * from oo for update nowait; > > hangs forever "select for update nowait" would raise an error if the tuple-level lock is being held by some other process; but what's making it wait here is the table-level lock. Now, is this the right behavior? I'm not sure. But I know for certain that making it behave as you expect is very tricky. The table lock is grabbed during parse analysis; we'd have to postpone grabbing the lock until after we have had the chance to notice that there's a FOR UPDATE clause for the table with a NOWAIT option attached. -- Álvaro Herrerahttp://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- 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] NOWAIT doesn't work
Hi, On Wednesday, October 31, 2012 02:51:38 PM Pavel Stehule wrote: > Hello > > it is expected behave? > > 1.session > > postgres=# begin; > BEGIN > postgres=# lock oo IN ACCESS EXCLUSIVE MODE; > LOCK TABLE > > 2. session > > postgres=# select * from oo for update nowait; > > hangs forever Yes, I think so. From the documentation: Note that NOWAIT applies only to the row-level lock(s) (http://www.postgresql.org/docs/9.2/static/sql-select.html) Greetings, CK -- 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] NOWAIT doesn't work
On 31 October 2012 14:52, Pavel Stehule wrote: > tested on 9.3 > > Pavel > > 2012/10/31 Pavel Stehule : > > Hello > > > > it is expected behave? > > > > 1.session > > > > postgres=# begin; > > BEGIN > > postgres=# lock oo IN ACCESS EXCLUSIVE MODE; > > LOCK TABLE > > > > 2. session > > > > postgres=# select * from oo for update nowait; > > > > hangs forever > > > > Regards > > > > Pavel Stehule > > I've checked on 9.1, works exactly the same. - Szymon
Re: [HACKERS] NOWAIT doesn't work
On Wednesday, October 31, 2012 02:51:38 PM Pavel Stehule wrote: > it is expected behave? > > 1.session > > postgres=# begin; > BEGIN > postgres=# lock oo IN ACCESS EXCLUSIVE MODE; > LOCK TABLE > > 2. session > > postgres=# select * from oo for update nowait; > > hangs forever NOWAIT is about row level locks, not about table level locks. Andres -- Andres Freund http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- 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] NOWAIT doesn't work
tested on 9.3 Pavel 2012/10/31 Pavel Stehule : > Hello > > it is expected behave? > > 1.session > > postgres=# begin; > BEGIN > postgres=# lock oo IN ACCESS EXCLUSIVE MODE; > LOCK TABLE > > 2. session > > postgres=# select * from oo for update nowait; > > hangs forever > > Regards > > Pavel Stehule -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
[HACKERS] NOWAIT doesn't work
Hello it is expected behave? 1.session postgres=# begin; BEGIN postgres=# lock oo IN ACCESS EXCLUSIVE MODE; LOCK TABLE 2. session postgres=# select * from oo for update nowait; hangs forever Regards Pavel Stehule -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
