On 2010-11-17 02:55, Josh Berkus wrote:
>> If you do wish to have the data tossed out for no good reason every so
>> often, then there ought to be a separate attribute to control that. I'm
>> really having trouble seeing how such behavior would be desirable enough
>> to ever have the server do it for you, on its terms rather than yours.
> I don't quite follow you. The purpose of unlogged tables is for data
> which is disposable in the event of downtime; the classic example is the
> a user_session_status table.
That sounds an awful lot like temporary tables. Perhaps the biggest
problem of "unlogged tables" is that it doesn't connote "truncate at
restart". With the truncate an unlogged table is more like a 'cluster
temporary table'. While this is a very ugly name, I wonder if an DBA
would expect a cluster temporary table to be backed up by default.
I just filled in the questionaire, and to my surprise I agreed more with
the 'don't backup by default' question. The reason is that because the
question also said: because it contains disposable data. Maybe a better
question would have been: would you expect pg_dump to backup unlogged
tables, at the point that you didn't more about them than that they are
not written to the WAL? In that case I'd say: yes.
regards,
Yeb Havinga
