Hello, Thanks Frederik for your quick feedback!
On Wed, 14 Jul 2010 12:26:57 +0200 Frederik Ramm <[email protected]> wrote: > Depends on what you define as "same result". If you make a full dump > of your PostgreSQL tables and then re-import that, you will be > somewhere at 122 GB or so. You could also do a "vacuum full" to > achieve the same result, or do a fresh import. But if you make a > comparison of the files in your /var/lib/postgresql directory, these > will not be the same as if you were to do a new import. The normal > vacuuming that PostgreSQL does is insufficient to release some > allocated space and later freed space in the data files, that's why > your database is larger that it would have to be. Your select results > will look the same. Yes, we understand that when we access the database, the results are the same, so from an user perspective, it makes no difference between having a fresh full import, or an old import that has been kept up-to-date using daily diffs. However, from a system administration point of view, having the database grow much faster than it really does (after 10 months, the database is 43% larger than it "really" is) is a little bit problematic. I suppose that similar things will happen with the minutely diffs, no ? Would working with minutely diffs make this any better or worse ? Unfortunately, as far as I understand, doing a "vacuum full" is going to block accesses to the database for a fairly long amount of time (days ?). So the best solution is probably to regularly (every few months) do a new full import in a separate database, and switch to this new database when the full import is completed. Thanks, Thomas -- Thomas Petazzoni http://thomas.enix.org MapOSMatic http://www.maposmatic.org
signature.asc
Description: PGP signature
