The tables INNODB_CMP and INNODB_CMP_RESET contain status information on the operations related to compressed tables, which are covered in Chapter 3, InnoDB Data Compression. The compressed page size is in the column PAGE_SIZE.

These two tables have identical contents, but reading from INNODB_CMP_RESET resets the statistics on compression and uncompression operations. For example, if you archive the output of INNODB_CMP_RESET every 60 minutes, you see the statistics for each hourly period. If you monitor the output of INNODB_CMP (making sure never to read INNODB_CMP_RESET), you see the cumulated statistics since InnoDB was started.

For the table definition, see Columns of INNODB_CMP and INNODB_CMP_RESET.