On Sun, Dec 20, 2009 at 2:12 AM, Andrus <kobrule...@hot.ee> wrote: >> You cannot access new values of a particular row within a single UPDATE >> statement, but you do see new values done in the same transaction. >> This is explain in some detail in the documentation: >> >> >> http://www.postgresql.org/docs/8.4/interactive/transaction-iso.html#XACT-READ-COMMITTED > > I tried > > drop table if exists tt ; > create temp table tt ( a int, b int ); > insert into tt values ( 1,2); > insert into tt values ( 3,4); > update tt set a=a*10, b=(select sum(a) from tt); > select * from tt > > b has value 4 for every row. > > So we *dont* see new values done in the same transaction. > How to fix ?
This isn't broken behaviour. First the inserts run and we have 1,2 3,4 When the update fires, the right hand side of the key/value pairs are evaluated simultaneously based on the data in the table AT THE TIME The query starts. b=sum(a) means b=sum(3,1) which means you're setting b=4... This was explained in a previous post by Tom I believe. Unless I'm missing what you're saying. -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
