Spec-Zone .ru
спецификации, руководства, описания, API
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Spec-Zone .ru
спецификации, руководства, описания, API
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The INNODB_CMPMEM and INNODB_CMPMEM_RESET tables
contain status information on compressed pages
within the InnoDB buffer pool.
Table 20.3. Columns of INNODB_CMPMEM and INNODB_CMPMEM_RESET
| Column name | Description |
|---|---|
PAGE_SIZE |
Block size in bytes. Each record of this table describes blocks of this size. |
PAGES_USED |
Number of blocks of the size PAGE_SIZE that are currently in use.
|
PAGES_FREE |
Number of blocks of the size PAGE_SIZE that are currently available
for allocation. This column shows the external fragmentation in the memory pool. Ideally, these
numbers should be at most 1.
|
RELOCATION_OPS |
Number of times a block of the size PAGE_SIZE has been relocated.
The buddy system can relocate the allocated "buddy neighbor"
of a freed block when it tries to form a bigger freed block. Reading from the table INNODB_CMPMEM_RESET resets this count.
|
RELOCATION_TIME |
Total time in microseconds spent in relocating blocks of the size PAGE_SIZE.
Reading from the tableINNODB_CMPMEM_RESET resets this count.
|
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.
For usage information, see Section
5.4.6.4, "Monitoring Compression at Runtime" and Section
14.2.4.3.1.3, "Using the Compression Information Schema Tables". For general information about InnoDB table compression, see Section
5.4.6, "Working with InnoDB Compressed Tables".