Обсуждение: last tuple affected
Hi all! Two related questions about a problem i'm trying to solve: How can I know the last tuple affected by an insert/update operation per table?? Is there exists any function in Postgres for retrieving some hash value from a table?? Thanks in advance. -- Miguel Ángel Tribaldos
Miguel Angel Tribaldos Hervas wrote: > Hi all! > > Two related questions about a problem i'm trying to solve: > How can I know the last tuple affected by an insert/update operation per > table?? > Is there exists any function in Postgres for retrieving some hash > value from a table?? You don't define what you mean by "last", and it's not a simple thing. You could attach triggers to the tables and have them record changes. Perhaps tell us what you are trying to do, rather than how you want to do it. -- Richard Huxton Archonet Ltd
I only need to know if a table has changed since the last check (create, update...), but I want to avoid a trigger + artificial records table. Is this information recorded somewhere, in a system table perhaps? What about a hash value refered to any table? Thanks. >>Miguel Angel Tribaldos Hervas wrote: >> Hi all! >> >> Two related questions about a problem i'm trying to solve: >> How can I know the last tuple affected by an insert/update operation per >> table?? >> Is there exists any function in Postgres for retrieving some hash >> value from a table?? > >You don't define what you mean by "last", and it's not a simple thing. >You could attach triggers to the tables and have them record changes. > >Perhaps tell us what you are trying to do, rather than how you want to >do it. >-- > Richard Huxton > Archonet Ltd >--
On Thu, Jan 27, 2005 at 12:45:13 +0100, Miguel Angel Tribaldos Hervas <mitriher@teleco.upv.es> wrote: > > I only need to know if a table has changed since the last check > (create, update...), but I want to avoid a trigger + artificial records table. > Is this information recorded somewhere, in a system table perhaps? > What about a hash value refered to any table? Remember there are different versions of tables that exist at the same time. If you really want to do the above, you will need to serialize access.