•Use the INFORMATION_SCHEMA COLUMNS  table or the SHOW COLUMNS  statement to view additional information about the columns of this table, including data types and default values. 

## 26.4.6 The INFORMATION_SCHEMA INNODB_CMP and INNODB_CMP_RESET Tables 

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

The INNODB_CMP  and INNODB_CMP_RESET  tables have these columns: 

• PAGE_SIZE 

The compressed page size in bytes. 

• COMPRESS_OPS 

The number of times a B-tree page of 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 

The number of times a B-tree page of size PAGE_SIZE  has been successfully compressed. This count should never exceed COMPRESS_OPS . 

• COMPRESS_TIME 

The total time in seconds used for attempts to compress B-tree pages of size PAGE_SIZE . 

• UNCOMPRESS_OPS 

The number of times a B-tree page of 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 

The total time in seconds used for uncompressing B-tree pages of the size PAGE_SIZE . 

mysql> SELECT * FROM INFORMATION_SCHEMA.INNODB_CMP\G *************************** 1. row *************************** page_size: 1024 compress_ops: 0 compress_ops_ok: 0 compress_time: 0  uncompress_ops: 0 uncompress_time: 0 *************************** 2. row *************************** page_size: 2048 compress_ops: 0 compress_ops_ok: 0 compress_time: 0  uncompress_ops: 0 uncompress_time: 0 *************************** 3. row *************************** page_size: 4096 compress_ops: 0 compress_ops_ok: 0 compress_time: 0 

