Re: Unlogged vs. In-Memory
Simon Riggs <simon@2ndquadrant.com>
From: Simon Riggs <simon@2ndQuadrant.com>
To: Kevin Grittner <Kevin.Grittner@wicourts.gov>
Cc: Joshua Berkus <josh@agliodbs.com>, Alvaro Herrera <alvherre@commandprompt.com>, Robert Haas <robertmhaas@gmail.com>, Rob Wultsch <wultsch@gmail.com>, Magnus Hagander <magnus@hagander.net>, Thom Brown <thom@linux.com>, PostgreSQL Advocacy <pgsql-advocacy@postgresql.org>
Date: 2011-05-05T19:52:11Z
Lists: pgsql-hackers
On Thu, May 5, 2011 at 8:45 PM, Kevin Grittner <Kevin.Grittner@wicourts.gov> wrote: > Simon Riggs <simon@2ndQuadrant.com> wrote: >> Kevin Grittner <Kevin.Grittner@wicourts.gov> wrote: >>> Simon Riggs <simon@2ndQuadrant.com> wrote: >>> >>>> I doubt that anyone wants the current behaviour. >>> >>> Current behavior would be an exact fit for a few use cases we >>> have. Attempting to salvage some portion of the data on startup >>> after a crash would yield it unusable for the uses I have in >>> mind. It would have either all be there, or all gone. > >> Those words have been taken out of context, leading to what looks >> to me like a confusion. > > Sorry, any misinterpretation wasn't intended. I just wanted to be > clear that for my purposes it would be best if lack of a clean > shutdown caused *all* non-logged tables to come up empty. I would > be using several of such tables to build up a single financial > transaction during user data entry. Since that would be going > through a connection pool, the shared visibility of the tables is a > necessity. > > In our current framework it is possible to bounce the database > server without interruption of user services beyond brief clocking, > which would be supported by saving the contents on clean shutdown > for restoration on startup. However, if the data appeared to be > present on startup, but portions of it were quietly missing or > modified, that could lead to the posting of an incorrect financial > transaction when the user was done and the software slammed data for > the WIP transaction into the permanent financial tables. > > If you're not proposing to break any of that, I can still move to > them from the "normal" permanent tables we're currently using. > > Again, if I misunderstood you, sorry for the noise. Your response is definitely about "the other thread" on hackers. Worth bringing it up because others might have been confused also. No problem, -- Simon Riggs http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services