Re: [PATCHES] [PATCH] Provide 8-byte transaction IDs to
От | Hannu Krosing |
---|---|
Тема | Re: [PATCHES] [PATCH] Provide 8-byte transaction IDs to |
Дата | |
Msg-id | 1153950186.2928.46.camel@localhost.localdomain обсуждение исходный текст |
Ответ на | Re: [PATCHES] [PATCH] Provide 8-byte transaction IDs to user level (Darcy Buskermolen <darcyb@commandprompt.com>) |
Список | pgsql-hackers |
Ühel kenal päeval, K, 2006-07-26 kell 14:27, kirjutas Darcy Buskermolen: > On Wednesday 26 July 2006 14:03, Tom Lane wrote: > > Darcy Buskermolen <darcyb@commandprompt.com> writes: > > >> The question though is if we did that, would Slony actually use it? > > > > > > If it made sence to do it, then yes we would do it. The problem ends up > > > being Slony is designed to work across a multitude of versions of PG, and > > > unless this was backported to at least 7.4, it would take a while (ie > > > when we stopped supporting versions older than it was ported into) > > > before we would make use of it. > > > > [ shrug... ] That's not happening; for one thing the change requires a > > layout change in pg_control and we have no mechanism to do that without > > initdb. > > I'll take a bit more of a look through the patch and see if it is a real boot > to use it on those platforms that support it, and that we have a suitable way > around it on those that don't. This patch is actually 2 things together: 1) fixing the xid wraparound and related btree brokenness by moving to 8byte txids represented as int8 2) cleaning up and exposing slony's snapshot usage. Slony stored snapshots in tables as separate xmin, xmax and list-of-running-transactions and then constructed the snapshot struct and used it internally. This patch exposes the snapshot it by providing a single snapshot type and operators for telling if any int8 trx is committed before or after this snapshot. This makes it possible to use txid and snapshots in a a query that does SELECT records FROM logtable WHERE txid BETWEEN snap1 AND snap2; that is it gets all records which are committed between two snapshots. > But at this point I wouldn't hold my breath on that Well, switching to using stuff from this patch would fix the data-corruption-after-2G problem for slony. That is unless thera are some bugs or thinkos of its own in this patch :) -- ---------------- Hannu Krosing Database Architect Skype Technologies OÜ Akadeemia tee 21 F, Tallinn, 12618, Estonia Skype me: callto:hkrosing Get Skype for free: http://www.skype.com
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