On Mon, 2008-09-29 at 11:18 -0400, Tom Lane wrote: > Simon Riggs <[EMAIL PROTECTED]> writes: > > On Mon, 2008-09-29 at 10:30 -0400, Tom Lane wrote: > >> Like what? > > > For constructing snapshots during standby. I need a data structure where > > emulated-as-running transactions can live. If backend birth/death is > > intimately tied to WAL visible events then I can use dummy PGPROC > > structures. If not, then I will have to create a special area that can > > expand to cater for the possibility that a backend dies and WAL replay > > won't know about it - which also means I would need to periodically dump > > a list of running backends into WAL. > > Mph. I find the idea of assuming that there must be an abort record to > be unacceptably fragile. Consider the possibility that the transaction > gets an error while trying to run AbortTransaction. Some of that code > is a CRITICAL_SECTION, but I don't think I like the idea that all of it > has to be one.
Aware of possibility fragility, hence the post. Few thoughts: * Is it close enough that we can get away with having a few spare slots to cater for that possibility? * Might we make AbortTransaction critical just as far as the END_CRIT_SECTION after XLogInsert in RecordTransactionAbort(), but no further? Don't expect yes, but seems worth recording thoughts. > > PANIC isn't a problem case because we'll end up generating a shutdown > > checkpoint which shows the backends have been terminated. > > Thought you were trying to get rid of the shutdown checkpoint during > restart? Yes, but if I do there would still be a WAL record of some kind there to allow us to confirm the change of tli. Anyway, I thought you wanted me to keep it now? -- Simon Riggs www.2ndQuadrant.com PostgreSQL Training, Services and Support -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
