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20.30.1. The INFORMATION_SCHEMA INNODB_CMP andINNODB_CMP_RESET Tables

The INNODB_CMP and INNODB_CMP_RESET tables contain status information on operations related to compressed InnoDB tables.

Table 20.1. Columns of INNODB_CMP andINNODB_CMP_RESET

Column name Description
PAGE_SIZE Compressed page size in bytes.
COMPRESS_OPS Number of times a B-tree page of the size PAGE_SIZE has been compressed. Pages are compressed whenever an empty page is created or the space for the uncompressed modification log runs out.
COMPRESS_OPS_OK Number of times a B-tree page of the size PAGE_SIZE has been successfully compressed. This count should never exceed COMPRESS_OPS.
COMPRESS_TIME Total time in seconds spent in attempts to compress B-tree pages of the size PAGE_SIZE.
UNCOMPRESS_OPS Number of times a B-tree page of the size PAGE_SIZE has been uncompressed. B-tree pages are uncompressed whenever compression fails or at first access when the uncompressed page does not exist in the buffer pool.
UNCOMPRESS_TIME Total time in seconds spent in uncompressing B-tree pages of the sizePAGE_SIZE.

Notes: