## E.176. Release 9.1.18

Release date: 2015-06-12

This release contains a small number of fixes from 9.1.17. For information about new features in the 9.1 major release, see Section E.194.

### E.176.1. Migration to Version 9.1.18

A dump/restore is not required for those running 9.1.X.

However, if you are upgrading from a version earlier than 9.1.16, see Section E.178.

### E.176.2. Changes

- Fix rare failure to invalidate relation cache init file (Tom Lane)

  With just the wrong timing of concurrent activity, a `VACUUM FULL` on a system catalog might fail to update the “init file” that's used to avoid cache-loading work for new sessions. This would result in later sessions being unable to access that catalog at all. This is a very ancient bug, but it's so hard to trigger that no reproducible case had been seen until recently.

- Avoid deadlock between incoming sessions and `CREATE/DROP DATABASE` (Tom Lane)

  A new session starting in a database that is the target of a `DROP DATABASE` command, or is the template for a `CREATE DATABASE` command, could cause the command to wait for five seconds and then fail, even if the new session would have exited before that.