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MySQL 8.4 Reference Manual  /  ...  /  The INFORMATION_SCHEMA INNODB_CMP and INNODB_CMP_RESET Tables

28.4.6 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.

Example

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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 uncompress_ops: 0 uncompress_time: 0 *************************** 4. row *************************** page_size: 8192 compress_ops: 86955 compress_ops_ok: 81182 compress_time: 27 uncompress_ops: 26828 uncompress_time: 5 *************************** 5. row *************************** page_size: 16384 compress_ops: 0 compress_ops_ok: 0 compress_time: 0 uncompress_ops: 0 uncompress_time: 0

Notes