Excerpts from Peter Eisentraut's message of mié dic 28 15:04:09 -0300 2011: > The check_postgres txn_wraparound action[0] runs this query: > > SELECT datname, age(datfrozenxid) AS age FROM pg_database WHERE > datallowconn ORDER BY 1, 2 > > On a hot standby, this fails with: > > ERROR: cannot assign TransactionIds during recovery > > So, a couple of things to wonder about: > > Is it unreasonable to check for transaction ID wraparound on a standby? > It should mirror the situation on the primary, shouldn't it? > > Should the age(xid) function do something more useful on a standby, > e.g., have a custom error message or return null or use the transaction > ID from the master?
I think we could just have the xid_age call GetCurrentTransactionIdIfAny, and if that returns InvalidXid, use ReadNewTransactionId instead. That xid_age assigns a transaction seems more of an accident than really intended. -- Álvaro Herrera <alvhe...@commandprompt.com> The PostgreSQL Company - Command Prompt, Inc. PostgreSQL Replication, Consulting, Custom Development, 24x7 support -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
