Search code examples
mysqljoinrowinnodb

Increase in InnoDB Row Operations

We have almost doubled the InnoDB Row Operations (Rows read) after a change.

The question I have is what exactly is this number representing. Is it the rows returned from the queries or is it the number of rows touched by the queries in different tables. We have introduced new tables to join. This should not have changed the amount of returned rows but clearly the amount of touched rows in the different tables.

Thanks for the help.

Solution

  • At the storage engine level (e.g. InnoDB), rows read refers to the physical rows read from each table. These rows are returned by the storage engine to the SQL layer of MySQL, where they are joined or filtered out by the conditions in your query.

    So it makes perfect sense that your rows read figure would increase when you join to a new table. It's counting rows read from each table.