On 6/1/14, 10:49 AM, Euler Taveira wrote:
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.

There's also things that pg_upgrade doesn't handle, so it's not always an 
Jim C. Nasby, Data Architect                       j...@nasby.net
512.569.9461 (cell)                         http://jim.nasby.net

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