Beginning in can run in parallel with normal database operations (selects, inserts, updates, deletes, but not changes to table definitions).
Routine vacuuming is therefore not nearly as intrusive as it was in prior releases, and it is not as critical to try to schedule it at low-usage times of day.
Beginning in of a row does not immediately remove the old version of the row.
But it is the database administrator's responsibility to set up appropriate scripts, and to check that they execute successfully.One obvious maintenance task is creation of backup copies of the data on a regular schedule.Without a recent backup, you have no chance of recovery after a catastrophe (disk failure, fire, mistakenly dropping a critical table, etc.).The backup and recovery mechanisms available in is low-maintenance compared to some other database management systems.Nonetheless, appropriate attention to these tasks will go far towards ensuring a pleasant and productive experience with the system.
operations performed for each of these reasons will vary depending on the needs of each site.
Therefore, database administrators must understand these issues and develop an appropriate maintenance strategy.
This section concentrates on explaining the high-level issues; for details about command syntax and so on, see the VACUUM reference page.
But eventually, an outdated or deleted row version is no longer of interest to any transaction.
The space it occupies must be reclaimed for reuse by new rows, to avoid infinite growth of disk space requirements.
This is done by running only selected tables, skipping tables that are known not to change often.