Is it feasible to use postgres 9 replication to reduce backup downtime?

I'm investigating strategies to reduce the maintenance downtime on a critical database. The DB contains bioinformatics data and is accessed by users in many different time zones around the world, 7 days a week (so off peak hours are limited). The database contains 10's of millions of rows and is growing rapidly.

As we are planning to upgrade to pg9, I want to find out if I can perform backups on a slave, so the master isn't affected. I am wondering if I should be very concerned about the slave getting too far 开发者_如何学编程behind on the log when a backup is in progress?

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If your database is too big or backups are too slow, you should be using WAL archiving as a backup method. You don't need PostgreSQL 9.0 for that. Having WAL archiving is a prerequisite for WAL-based replication, so you'd almost get it for free if you are interested in the replication feature in 9.0.

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There is no downtime during backup. Why do you think the database is down?

From the manual:

pg_dump does not block other users accessing the database (readers or writers).