Consistent pg_dump's
Are pg_dump's consistent? Do i have to shutdown the system in order to make
a pg_dump? What other alternatives are for backing up a database without
shutting down the system in order to allow consistent backups?
Another question: Can the rows that haven't been vaccumed yet retrieved?
Thanks for your help. Bye!!
Alexey
Doug McNaught <doug@wireboard.com> writes:
I am pretty sure that pg_dump produces a consistent snapshot, using
the same transaction isolation mechanism (MVCC) as the database
itself. If one of the gurus posts and says otherwise, believe him,
not me. ;)
Yes, you are right, this is done in pg_dump with the command:
set transaction isolation level serializable
Regards,
Manuel.
Import Notes
Reply to msg id not found: DougMcNaught'smessageof29Mar2001180925-0500
Alexey Rodriguez Yakushev <alexey@serinbol.com> writes:
Let me rephrase the question, i have a web-based application which uses
postgres as its backend. It must be operating 24 hours 7 days. If i want to
make a backup of the database using pg_dump, wouldn't it be possible that a
transaction occurs in the middle of the backup, leaving the backup
inconsistent?
I am pretty sure that pg_dump produces a consistent snapshot, using
the same transaction isolation mechanism (MVCC) as the database
itself. If one of the gurus posts and says otherwise, believe him,
not me. ;)
-Doug
Import Notes
Reply to msg id not found: AlexeyRodriguezYakushev'smessageofThu29Mar2001191256-0400
* Doug McNaught <doug@wireboard.com> [010329 15:22] wrote:
Alexey Rodriguez Yakushev <alexey@serinbol.com> writes:
Let me rephrase the question, i have a web-based application which uses
postgres as its backend. It must be operating 24 hours 7 days. If i want to
make a backup of the database using pg_dump, wouldn't it be possible that a
transaction occurs in the middle of the backup, leaving the backup
inconsistent?I am pretty sure that pg_dump produces a consistent snapshot, using
the same transaction isolation mechanism (MVCC) as the database
itself. If one of the gurus posts and says otherwise, believe him,
not me. ;)
My impression from reading the source was that it was consitant per-table
but not per-database. Meaning you'd get a consistant snapshot of a table,
but not of the entire system.
I could be wrong though.
--
-Alfred Perlstein - [bright@wintelcom.net|alfred@freebsd.org]
Represent yourself, show up at BABUG http://www.babug.org/
I am pretty sure that pg_dump produces a consistent snapshot, using
the same transaction isolation mechanism (MVCC) as the database
itself. If one of the gurus posts and says otherwise, believe him,
not me. ;)My impression from reading the source was that it was consitant per-table
but not per-database. Meaning you'd get a consistant snapshot of a table,
but not of the entire system.I could be wrong though.
I hope so... that could break some foreign key dependencies pretty badly...
Greg