Tom Lane wrote: > Hannu Krosing <[EMAIL PROTECTED]> writes: > > DB2 can run in two modes > > 1) similar to ours, where logs are reused after checkpoints/commits > > allow it. > > 2) with log archiving: logs are never reused, but when system determines > > it no longer needs them, it will hand said log over to archiving process > > that will archive it (usually do a backup to some other place and then > > delete it). > > There is in fact the skeleton of support in xlog.c for passing unwanted > log segments over to an archiver, rather than recycling them. So far > no one's done anything with the facility. I think the main problem is > the one Bruce cited: because the WAL representation is tied to physical > tuple locations and so forth, it's only useful to a slave that has an > *exact* duplicate of the master's entire database cluster. That's not > useless, but it's pretty restrictive. > > It could be useful for incremental backup, though I'm not sure how > efficient it is for the purpose. WAL logs tend to be pretty voluminous. > At the very least you'd probably want enough smarts in the archiver to > strip out the page-image records.
Yes, I think the bottom line is that we would need to add some things to the WAL file to make archiving the logs work, for either point-in-time recovery, or replication, both of which we need. -- Bruce Momjian | http://candle.pha.pa.us [EMAIL PROTECTED] | (610) 853-3000 + If your life is a hard drive, | 830 Blythe Avenue + Christ can be your backup. | Drexel Hill, Pennsylvania 19026 ---------------------------(end of broadcast)--------------------------- TIP 6: Have you searched our list archives? http://archives.postgresql.org
