Thanks Miguel, Very informative. I'm using Frontbase. I cleaned out a lot of unneeded rows in several tables in hopes that it would speed by pre-fetching. Sounds like most of the extra info produced by this will remain on the disc. Is there a size of the database where you may want to "vacuum"? I'm setting at about 200 Meg saved for a uncompressed backup using the Frontbase "live" backup method.
Jeff On Tuesday, March 17, 2009, at 08:04AM, "Miguel Arroz" <[email protected]> wrote: >Hi! > > Jeff, this depends on the DB engine you are using. > > On Postgresql, you have two sets of files. The base files, which >contains the "stable" data, and the write-ahead logs (WALs). Every >time you do an operation, whatever that is (including delete), the >operation is written to the WALs. Data in WALs is never overwritten, >only appended. > > From time to time (namely, when a WAL file is full - usually 16 MB, >and when no active transaction is using that file) the data on the WAL >files is copied back to the base files, and the WALs are discarded. > > Even so, this might not release unused space. To do that, you have >to run VACUUM queries. Note that running VACUUM on a table (or the >entire DB) is a very heavy process, specially for the disks, so it >will kill your DB performance while it's being done. Anyway, you don't >really need to, because PostgreSQL will be able to use the unused >space in a smart way, and it automatically vacuums some tables from >time to time. > > Note also that each DB has it's own procedure for making a correct >backup (ie, a backup you are 100% sure it's consistent and will work >if recovery is needed). Here's what you should do for PostgreSQL: >http://www.postgresql.org/docs/8.1/interactive/backup.html > . Note that, on most DBs (if not all), simply copying the DB files >for another drive is NOT a safe way to backup, your backup will most >probably be corrupt. You have to make the backups in accordance with >the DB engine itself. > > Yours > >Miguel Arroz > > >On 2009/03/17, at 09:02, Jeff Schmitz wrote: > >> This may be a dumb question, but why after deleting a bunch of EOs >> is my database backup larger than before? Looking at the data in >> the database, the data corresponding to the EOs does seem to be gone >> now. >> >> Jeff >> _______________________________________________ >> Do not post admin requests to the list. They will be ignored. >> Webobjects-dev mailing list ([email protected]) >> Help/Unsubscribe/Update your Subscription: >> http://lists.apple.com/mailman/options/webobjects-dev/arroz%40guiamac.com >> >> This email sent to [email protected] > >........................... >http://www.survs.com > > _______________________________________________ Do not post admin requests to the list. They will be ignored. Webobjects-dev mailing list ([email protected]) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/webobjects-dev/archive%40mail-archive.com This email sent to [email protected]
