MySQL :: MySQL 8.4 参考手册 :: 28.4.7 INFORMATION_SCHEMA INNODB_CMPMEM 和 INNODB_CMPMEM

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MySQL 8.4 参考手册 / 28 个 INFORMATION_SCHEMA 表 / 28.4 INFORMATION_SCHEMA InnoDB 表 / 28.4.7 INFORMATION_SCHEMA INNODB_CMPMEM 和 INNODB_CMPMEM_RESET 表

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28.4.7 INFORMATION_SCHEMA 中的 INNODB_CMPMEM 和 INNODB_CMPMEM_RESET 表28.4.7 The INFORMATION_SCHEMA INNODB_CMPMEM and INNODB_CMPMEM_RESET Tables

INNODB_CMPMEM 和 INNODB_CMPMEM_RESET 表提供了 InnoDB 缓冲池中已压缩页的状态信息。The INNODB_CMPMEM and INNODB_CMPMEM_RESET tables provide status information on compressed pages within the InnoDB buffer pool.

INNODB_CMPMEM 和 INNODB_CMPMEM_RESET 表具有以下列：The INNODB_CMPMEM and INNODB_CMPMEM_RESET tables have these columns:

PAGE_SIZE
以字节为单位的块大小。此表的每条记录描述该大小的块。The block size in bytes. Each record of this table describes blocks of this size.
BUFFER_POOL_INSTANCE
缓冲池实例的唯一标识符。A unique identifier for the buffer pool instance.
PAGES_USED
当前正在使用的 PAGE_SIZE 大小块的数量。The number of blocks of size PAGE_SIZE that are currently in use.
PAGES_FREE
当前可用于分配的 PAGE_SIZE 大小的区块数量。此列显示内存池中的外部碎片情况。理想情况下，这些数字应最多为 1。The number of blocks of 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
大小为 PAGE_SIZE 的区块被重新定位的次数。当尝试形成更大的空闲区块时，伙伴系统可以重新定位已分配区块的“伙伴邻居”。从 INNODB_CMPMEM_RESET 表读取数据会重置此计数。The number of times a block of 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 INNODB_CMPMEM_RESET table resets this count.
RELOCATION_TIME
用于重新定位大小为 PAGE_SIZE 的块的总时间（以微秒为单位）。从表 INNODB_CMPMEM_RESET 读取将重置此计数。The total time in microseconds used for relocating blocks of size PAGE_SIZE. Reading from the table INNODB_CMPMEM_RESET resets this count.

示例Example

mysql> SELECT * FROM INFORMATION_SCHEMA.INNODB_CMPMEM\G
*************************** 1. row ***************************
           page_size: 1024
buffer_pool_instance: 0
          pages_used: 0
          pages_free: 0
      relocation_ops: 0
     relocation_time: 0
*************************** 2. row ***************************
           page_size: 2048
buffer_pool_instance: 0
          pages_used: 0
          pages_free: 0
      relocation_ops: 0
     relocation_time: 0
*************************** 3. row ***************************
           page_size: 4096
buffer_pool_instance: 0
          pages_used: 0
          pages_free: 0
      relocation_ops: 0
     relocation_time: 0
*************************** 4. row ***************************
           page_size: 8192
buffer_pool_instance: 0
          pages_used: 7673
          pages_free: 15
      relocation_ops: 4638
     relocation_time: 0
*************************** 5. row ***************************
           page_size: 16384
buffer_pool_instance: 0
          pages_used: 0
          pages_free: 0
      relocation_ops: 0
     relocation_time: 0

备注Notes

使用这些表来衡量数据库中InnoDB表压缩的效果。Use these tables to measure the effectiveness of InnoDB table compression in your database.
你必须拥有 PROCESS 权限才能查询此表。You must have the PROCESS privilege to query this table.
使用 INFORMATION_SCHEMA COLUMNS 表或 SHOW COLUMNS 语句查看关于此表列的更多信息，包括数据类型和默认值。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.
有关使用信息，请参见第 17.9.1.4 节，“运行时监控 InnoDB 表压缩”和第 17.15.1.3 节，“使用压缩信息模式表”。有关InnoDB表压缩的一般信息，请参见第 17.9 节，“InnoDB 表和页面压缩”。For usage information, see Section 17.9.1.4, “Monitoring InnoDB Table Compression at Runtime” and Section 17.15.1.3, “Using the Compression Information Schema Tables”. For general information about InnoDB table compression, see Section 17.9, “InnoDB Table and Page Compression”.

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