Problem

You want to determine the last modified timestamp for a Delta table. You rely on the last_altered column in the system.information_schema.tables, but notice this column doesn't always reflect the correct timestamp when the table experiences updates or inserts.

Cause

The last_altered column in the system.information_schema.tables displays the timestamp when the table's structure was last modified (such as changes to the table schema, metadata, or table properties). 

It does not track data modifications such as inserts, updates, or deletes, so does not show a timestamp for the table’s data changes. 

Solution

To accurately track when a Delta table’s structure or data was last modified, use the lastModified column returned by the DESCRIBE DETAIL command. 

%sql
DESCRIBE DETAIL <your-catalog>.<your-schema>.<your-table-name>;

DESCRIBE DETAIL returns comprehensive table information, including the timestamp that reflects the most recent modification to the table's data or structure.