pg_dump consistency.

Marc Wrubleski wrote:

Hi all,

I have been reading but cannot find this particular bit of info.

I need to guarantee to my customer that the pg_dump is consistent. I
couldn't guarantee consistency if the pg_dump is run while the db is
on-line, and we cannot take the db off-line to do backups.

So, can anyone tell me
1. IF pg_dump is consistent (without taking the db offline),

Yes

2. if so, how does it do it?

As with any other SQL query, pg_dump ignores any transaction started
or completed after its own start.

--
Oliver Elphick Oliver.Elphick@lfix.co.uk
Isle of Wight http://www.lfix.co.uk/oliver
PGP: 1024R/32B8FAA1: 97 EA 1D 47 72 3F 28 47 6B 7E 39 CC 56 E4 C1 47
GPG: 1024D/3E1D0C1C: CA12 09E0 E8D5 8870 5839 932A 614D 4C34 3E1D 0C1C
========================================
"Finally, brethren, whatsoever things are true,
whatsoever things are honest, whatsoever things are
just, whatsoever things are pure, whatsoever things
are lovely, whatsoever things are of good report; if
there be any virtue, and if there be any praise, think
on these things." Philippians 4:8

hi Marc
If u log all the queries which get executed when a dump takes place u
will find that the pg_dump process first sets the transaction isolation
level to serializable..

So i guess all the state of the database dumped is consistent with a
point in time..

Hope this helps
Anand