Le Wed, 22 Jun 2016 18:07:46 +0800, Vlad Arkhipov <arhipov@xxxxxxxxxxxx> a écrit : > I am running PostgreSQL 9.5. > > CREATE TABLE t (id BIGINT NOT NULL PRIMARY KEY, name TEXT); I guess this is not your definitive definition of the table and you might have some other fields isn't it ? I can see multiple way to change this schema that seems broken, but we probably lack informations to pick the right one... > The constraint that the data must satisfy is `there is no more than 3 > records with the same name`. > > I am not in control of queries that modify the table, so advisory locks > can hardly be of help to me. > > On 06/22/2016 05:20 PM, Sameer Kumar wrote: > > > > > > On Wed, Jun 22, 2016 at 5:10 PM Vlad Arkhipov <arhipov@xxxxxxxxxxxx > > <mailto:arhipov@xxxxxxxxxxxx>> wrote: > > > > Hello, > > > > I have a constraint that requires a table to be locked before checking > > it (i.e. no more than 2 records with the same value in the same > > column). > > If I lock the table in the SHARE ROW EXCLUSIVE mode, any vacuuming (or > > autovacuuming) process prevents me from checking the constraint. What > > are possible solutions? > > > > > > May be you would like to share- > > - Table Structure > > - PostgreSQL version > > > > This will help people who would try to help you. > > > > I think you might want to consider an optimistic way of locking your > > records, instead of locking them. Or look at advisory locks (but that > > depends on your Postgres version). -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
