On 01-06-2014 02:57, Andres Freund wrote: > On 2014-06-01 00:50:58 -0500, Jim Nasby wrote: >> On 5/31/14, 9:11 AM, Andres Freund wrote: >>> On 2014-02-21 15:14:15 -0600, Jim Nasby wrote: >>>> On 2/17/14, 7:31 PM, Robert Haas wrote: >>>>> But do you really want to keep that snapshot around long enough to >>>>> copy the entire database? I bet you don't: if the database is big, >>>>> holding back xmin for long enough to copy the whole thing isn't likely >>>>> to be fun. >>>> >>>> I can confirm that this would be epic fail, at least for londiste. It >>>> takes about 3 weeks for a new copy of a ~2TB database. There's no way >>>> that'd work with one snapshot. (Granted, copy performance in londiste is >>>> rather lackluster, but still...) >>> >>> I'd marked this email as todo: >>> If you have such a huge database you can, with logical decoding at >>> least, use a basebackup using pg_basebackup or pg_start/stop_backup() >>> and roll forwards from that... That'll hopefull make such huge copies >>> much faster. > >> Just keep in mind that one of the use cases for logical replication is >> upgrades. > > Should still be fine. Make a physical copy; pg_upgrade; catchup via > logical rep. > Have in mind that it is not an option if you want to copy *part* of the database(s) (unless you have space available and want to do the cleanup after upgrade). In a near future, a (new) tool could do (a) copy schema, (b) accumulate modifications while copying data, (c) copy whole table and (d) apply modifications for selected table(s)/schema(s). Such a tool could even be an alternative to pg_upgrade.
-- Euler Taveira Timbira - http://www.timbira.com.br/ PostgreSQL: Consultoria, Desenvolvimento, Suporte 24x7 e Treinamento -- Sent via pgsql-hackers mailing list (email@example.com) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers