On Thu, Jun 23, 2016 at 10:54 AM, Sameer Kumar <sameer.kumar@xxxxxxxxxx> wrote: > > > On Fri, 24 Jun 2016, 1:47 a.m. Jeff Janes, <jeff.janes@xxxxxxxxx> wrote: >> >> On Thu, Jun 23, 2016 at 8:14 AM, Sameer Kumar <sameer.kumar@xxxxxxxxxx> >> wrote: >> > >> > Hi, >> > >> > I just wanted to understand what are the commands which will acquire >> > Access >> > Exclusive Lock on a table? In my knowledge below operations will acquire >> > access exclusive lock:- >> > >> > 1. VACUUM FULL >> > 2. ALTER TABLE >> > 3. DROP TABLE >> > 4. TRUNCATE >> > 5. REINDEX >> > 6. LOCK command with Access Exclusive Mode (or no mode specified) >> > >> > I am using PostgreSQL v9.4. >> >> A regular VACUUM (not a FULL one), including autovac, will take an >> ACCESS EXCLUSIVE lock if it believes there are enough empty >> (truncatable) pages at the end of the table to be worth truncating and >> returning that storage to the OS. On master it will quickly abandon >> the lock if it detects someone else wants it, but that does not work >> on a standby. > > > Thanks! This is helpful. I believe going by this explaination I can try to > reproduce this issue manually. > > Is this part about regular vacuum acquiring an AccessExclusive Lock > documented? I did not see a reference to it on page for Explicit Locking. Not that I know of. I don't think any part of the user documentation attempts to make an exhaustive list of all actions which take which level of locks. It only provides some illustrative examples. Cheers, Jeff -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
