Nov2013ReplicationIssue

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DRAFT: descriptions below are not yet verified!

What is the November 2013 Replication Data Loss Issue?

This is an issue, discovered Nov. 18, 2013., which can cause minor data corruption in a streaming replica.

Hackers mailing list discussion here

What are the symptoms of the issue?

The primary symptom of this corruption is rows that are present on the primary, but missing on the secondary; you may also experience duplicated records on the secondary compared to the primary. In general, the issue affects only a handful of rows.

Who is at risk for this issue?

Users who:

  • are on one of the following PostgreSQL versions: 9.3.0, 9.3.1, 9.2.5, 9.1.10, and 9.0.14
  • are using streaming replication
  • have created a new replication clone since updating to one of the above versions
  • have a heavy-write workload

Note that the workload which triggers this issue is still not precisely understood; it does not affect all users with heavy write workloads.

When will this be fixed?

The PostgreSQL project will be releasing an update release in early December which fixes this issue. We strongly advise all users who are using replication to apply that update as soon as it comes out.

What can I do to prevent this issue until then?

Options:

  • start your replica by taking a clone with write traffic halted on the master (i.e. a downtime)
  • if you are on 9.2.5, 9.1.10 or 9.0.14, downgrade your replication master to the prior update release (9.2.4, 9.1.9 or 9.0.13).

In any case, we recommend that all users who were running streaming replication under one of the affected versions re-clone each of their replicas, either:

  • during a downtime,
  • after downgrading the master, or
  • after applying the update when it comes out.

How can I verify whether I already have this corruption?

That is not yet determined.

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