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 and
INNODB_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 size
PAGE_SIZE. |
Notes:
Use these tables to measure the effectiveness of
InnoDBtable compression in your database. For usage information, see Section 13.7.6.1.3, “Using the Compression Information Schema Tables”.