PostgreSQL 11 Administration Cookbook

How to do it…

There are two routes that a row can take in PostgreSQL—a row version dies and needs to be removed by VACUUM, or a row version gets old enough and needs to be frozen, which is also performed by the VACUUM process.

Why do we care? Suppose that we load a table with 100 million rows, and everything is fine. When those rows have been there long enough to begin being frozen, the next VACUUM operation on that table will rewrite all of them to freeze their transaction identifiers. Put another way, autovacuum will wake up and start using lots of I/O to perform the freezing.

The most obvious way to forestall this problem is to explicitly vacuum a table after a major load. Of course, that doesn't remove the problem entirely, and you might ...