Can you explain what the ANALYZE command in SQL means and why it is used?

The ANALYZE command in SQL is used to gather statistics about the contents of tables and indexes in a database. These statistics help the query optimizer make more efficient decisions when planning query execution.

For example, after significant data changes (inserts, updates, deletes), it is useful to run ANALYZE to update the statistics and improve query performance.

In PostgreSQL, it looks like this:

ANALYZE table_name;

Or for the entire database:

ANALYZE;

Thus, ANALYZE does not modify data but updates metadata used by the optimizer.