If you're looking for help with Replication, you've come to the right place. 2ndQuadrant designed and wrote PostgreSQL's Point in Time Recovery (PITR) and Warm Standby replication features. We've been actively maintaining them over the last 4 major releases of PostgreSQL and we're working on the future too, sometimes with sponsorship from other companies and major users.

We offer architecture & design services, implementation, training and technical support. We also provide low-level database recovery services, for when disaster strikes. The information in the sections below is maintained to assist you.

We also know replication means different things to different people. Our approach is to understand your requirements for High Availability, Data Integration, Archiving etc. and optimise the solution for your business. Whether it's a one-off project or you need permanent infrastructure, we can help. Upgrades, RDBMS Migrations, Exploration Data Marts, Data Warehouses, Straight Through Processing. Whatever the reason, we've got the experience.

Warm Standby Servers for High Availability

PostgreSQL 8.2 and 8.3 provide a simple, fast and stable replication mechanism, known as Warm Standby, though more accurately described as Log Shipping. Data from the transaction log, also known as the Write Ahead Log (WAL) is transported to a standby server where continuous recovery takes place. It's a simple and elegant solution, relying on the underlying recovery code to perform changes on the standby node, so there is only minimal overhead on the primary server.

Data is currently shipped one file at a time, offering file based asynchronous replication. The entire database server is replicated, so there is no additional administration for each table or for each database. Replication can be fast in many circumstances and utilises WAN links effectively. The standby node cannot yet be accessed to perform queries.

We're working on further updates to this replication mechanism, covering:

• Data streaming
• Synchronous Replication
• Read Only Standby Servers, also known as Hot Standby
• Increased replication performance

Postgres log shipping works using similar concepts to the following products options in other RDBMS (trademarks acknowledged appropriately):

• Oracle Data Guard
• IBM DB2 HADR
• Microsoft SQL Server Log Shipping
• Informix HDR (On-Bar)

Sections

• High Availability