On Mon, Aug 15, 2011 at 5:15 PM, Magnus Hagander <mag...@hagander.net> wrote: > On Mon, Aug 15, 2011 at 18:12, Tom Lane <t...@sss.pgh.pa.us> wrote: >> Heikki Linnakangas <heikki.linnakan...@enterprisedb.com> writes: >>> Perhaps we should change the protocol so that it explicitly says which >>> file the streamed piece of WAL belongs to. That way a client could write >>> it to the correct file without knowing about all those macros. >> >> Yeah, maybe. Otherwise, all that logic is not only implicitly part of >> the protocol, but essentially impossible to change because it'll be >> hard-coded into clients. I wasn't too worried about this before because >> I supposed that only walsender and walreceiver really needed to know > > Wouldn't doing that cause significant overhead? Every single packet > would have to contain the filename, since the wal stream isn't > depending onthe filenames in where it cuts off. Also, the way it is > now a single packet on the replication stream can span multiple WAL > files... (This is the bug in my previous version that I've been able > to fix now)
Why not have a specific protocol message to indicate a change of filename? I don't mean a WAL message, I mean a streaming protocol message. At present the WALSender only sends from one file at a time, so sending a message when we open a new file would be straightforward. Magnus needs some things to make this work for 9.0/9.1, but we don't need to change 9.2 to allow that, we just need to copy the definitions for those now-fixed releases. -- Simon Riggs http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
