How to do it…
PostgreSQL does not have any built-in last used information about tables, so you have to use other means to figure it out.
If you have set up a cron job to collect usage statistics, as described in the previous chapter, then it is relatively easy to find out the last date of change using a SQL query.
Other than this, there are basically two possibilities, neither of which gives you absolutely reliable answers.
You can either look at the actual timestamps of the files in which the data is stored, or you can use the xmin and xmax system columns to find out the latest transaction ID that changed the table data.
In this recipe, we cover the first case and focus on the date information in the table's files.
The following PL/pgSQL ...
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Read now
Unlock full access