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How is the archiving done in PostgreSQL database?
To provide the database administrator with flexibility, PostgreSQL tries not to make any assumptions about how the archiving will be done. Instead, PostgreSQL lets the administrator specify a shell command to be executed to copy a completed segment file to wherever it needs to go.
How to do point in time recovery ( PITR )?
Continuous Archiving and Point-in-Time Recovery (PITR) 25.3. Continuous Archiving and Point-in-Time Recovery (PITR) Chapter 25. Backup and Restore 25.3. Continuous Archiving and Point-in-Time Recovery (PITR) 25.3.1. Setting Up WAL Archiving 25.3.2. Making a Base Backup 25.3.3. Making a Base Backup Using the Low Level API 25.3.4.
Why do we need continuous backup in PostgreSQL?
So we do not need a file system snapshot capability, just tar or a similar archiving tool. Since we can combine an indefinitely long sequence of WAL files for replay, continuous backup can be achieved simply by continuing to archive the WAL files.
Where is the write ahead log in PostgreSQL?
At all times, PostgreSQL maintains a write ahead log (WAL) in the pg_wal/ subdirectory of the cluster’s data directory. The log records every change made to the database’s data files.
How to do point in time recovery in PostgreSQL?
Replaying all WALs will result in the same state where we had made some mistake. There are two important prerequisites required for PITR to work. In order to achieve the PITR, the first step would be to restore an earlier taken base backup and then create a recovery setup. The setup requires configuring restore_command and recovery_target options.
Can You restore a configuration file in PostgreSQL?
Note that although WAL archiving will allow you to restore any modifications made to the data in your PostgreSQL database, it will not restore changes made to configuration files (that is, postgresql.conf, pg_hba.conf and pg_ident.conf ), since those are edited manually rather than through SQL operations.
How are segment files recycled in PostgreSQL documentation 9.1?
When not using WAL archiving, the system normally creates just a few segment files and then “recycles” them by renaming no-longer-needed segment files to higher segment numbers. It’s assumed that segment files whose contents precede the checkpoint-before-last are no longer of interest and can be recycled.