On 01/21/10 16:09, John Mitchell wrote:
So am I to presume that the current stable version of postgres (before 8.5) does require extra locking?
There is currently (before 8.5) no official replication mechanism in PostgreSQL. There are some 3rd party implementations, for which information can be gathered here:
http://www.postgresql.org/docs/current/interactive/high-availability.html http://wiki.postgresql.org/wiki/Replication,_Clustering,_and_Connection_Pooling
2010/1/21 Grzegorz Jaśkiewicz <gryzman@xxxxxxxxx <mailto:gryzman@xxxxxxxxx>> On Thu, Jan 21, 2010 at 1:12 PM, John Mitchell <mitchelljj98@xxxxxxxxx <mailto:mitchelljj98@xxxxxxxxx>> wrote: > Hi, > > In reading the documentation it states that the SQL dump backup does not > block other operations on the database while it is working. yes, pg_dump opens serializable transaction thus guarantees data to be the exact snapshot (as opposed to the default isolation level, which is called 'read commited' not without reason). > > I presume that while a restore is occurring that no reads or updates are > allowed against the restored database. nope, what restoring does, is just running all the commands in the pg_dump (whether it is binary or textual). So as soon as the database is created, it is treated just as any connection, thus allows you to connect and use it. > What locking mechanism is used for Master-Slave Replication? master slave that's introduced in what's to be 9.0 (aka 8.5), uses WAL shipping. So it doesn't require any extra locking. -- GJ -- John J. Mitchell
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