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25.38.5 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 exceedCOMPRESS_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
- *************************** 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
Use these tables to measure the effectiveness of
InnoDB
table compression in your database.You must have the
PROCESS
privilege to query this table.Use the
INFORMATION_SCHEMA
COLUMNS
table or theSHOW COLUMNS
statement to view additional information about the columns of this table, including data types and default values.For usage information, see Section 15.9.1.4, “Monitoring InnoDB Table Compression at Runtime” and Section 15.14.1.3, “Using the Compression Information Schema Tables”. For general information about
InnoDB
table compression, see Section 15.9, “InnoDB Table and Page Compression”.
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Document créé le 26/06/2006, dernière modification le 26/10/2018
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