On Wed, Jan 29, 2014 at 3:11 PM, Simon Riggs <si...@2ndquadrant.com> wrote: > On 14 January 2014 08:38, Christian Kruse <christ...@2ndquadrant.com> wrote: >> Hi, >> On 13/01/14 20:06, Heikki Linnakangas wrote: >>> On 12/17/2013 04:58 PM, Christian Kruse wrote: >>> >attached you will find a patch for showing the current transaction id >>> >(xid) and the xmin of a backend in pg_stat_activty and the xmin in >>> >pg_stat_replication. >>> >>> Docs. >> >> Thanks, update with updated docs is attached. > > Looks simple enough and useful for working out which people are > holding up CONCURRENT activities. > > I've not been involved with this patch, so any objections to me doing > final review and commit?
Nope, but I think this patch is broken. It looks to me like it's conflating the process offset in the BackendStatus array with its backendId, which does not seem like a good idea even if it happens to work at present. And the way BackendIdGetProc() is used looks unsafe, too: the contents might no longer be valid by the time we read them. I suspect we should have a new accessor function that takes a backend ID and copies the xid and xmin to pointers provided by the client while holding the lock. I also note that the docs seem to need some copy-editing: + <entry>The current <xref linked="ddl-system-columns">xmin value.</xref></entry> -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers