Pg_xlog file size

In short, it is well worth your while to setup something that will monitor the count of WAL files for each Postgres server. Ideally, the number of files at any given time should lie between an upper and lower limit, with predictable variations arising from maintenance tasks and batch workloads.

Spikes in WAL file count are typically caused by VACUUM-like maintenance tasks that create large volume of changes, or temporary tables and objects in a short period of time. These should come slowly back down to normal levels. Increases in the count that refuse to come back down have to be dealt with quickly. These can be because of:. You should also have a way to correlate this count with the PostgreSQL activity going on at a specific time.

Note: When everything is back to normal, don't forget to recreate this file in case you want to use it in future. Our priority is to find the WAL log where the checkpoint is writing currently. It is always safe to execute a dry run with option —n first and then use —d option to delete them later. Note: Once you have done all of the above, you should take a fresh backup of your cluster. All Rights Reserved.

Copyright Fujitsu Australia Software Technology. Fujitsu PostgreSQL blog. Transaction logs are a core component of all modern Relational Database Management Systems. They are designed to deliver improved performance.

You will see the following messages after this problem arises. What is Wal buffer? XLOG records are written into the in-memory WAL buffer by change operations such as insertion, deletion, or commit action.

What is streaming replication? This feature was added to PostgreSQL 9. The discussion below is a developer oriented one that contains some out of date information. Each segment is normally 16 megabytes. This documentation is for an unsupported version of PostgreSQL. You may want to view the same page for the current version, or one of the other supported versions listed above instead.

PostgreSQL 9. Reliability and the Write-Ahead Log Next.