- 20.30 INFORMATION_SCHEMA Tables for InnoDB
- 20.30.1 The INFORMATION_SCHEMA INNODB_CMP and INNODB_CMP_RESET Tables
- 20.30.2 The INFORMATION_SCHEMA INNODB_CMP_PER_INDEX and INNODB_CMP_PER_INDEX_RESET Tables
- 20.30.3 The INFORMATION_SCHEMA INNODB_CMPMEM and INNODB_CMPMEM_RESET Tables
- 20.30.4 The INFORMATION_SCHEMA INNODB_TRX Table
- 20.30.5 The INFORMATION_SCHEMA INNODB_LOCKS Table
- 20.30.6 The INFORMATION_SCHEMA INNODB_LOCK_WAITS Table
- 20.30.7 The INFORMATION_SCHEMA INNODB_SYS_TABLES Table
- 20.30.8 The INFORMATION_SCHEMA INNODB_SYS_INDEXES Table
- 20.30.9 The INFORMATION_SCHEMA INNODB_SYS_COLUMNS Table
- 20.30.10 The INFORMATION_SCHEMA INNODB_SYS_FIELDS Table
- 20.30.11 The INFORMATION_SCHEMA INNODB_SYS_FOREIGN Table
- 20.30.12 The INFORMATION_SCHEMA INNODB_SYS_FOREIGN_COLS Table
- 20.30.13 The INFORMATION_SCHEMA INNODB_SYS_TABLESTATS View
- 20.30.14 The INFORMATION_SCHEMA INNODB_BUFFER_PAGE Table
- 20.30.15 The INFORMATION_SCHEMA INNODB_BUFFER_PAGE_LRU Table
- 20.30.16 The INFORMATION_SCHEMA INNODB_BUFFER_POOL_STATS Table
- 20.30.17 The INFORMATION_SCHEMA INNODB_METRICS Table
- 20.30.18 The INFORMATION_SCHEMA INNODB_FT_CONFIG Table
- 20.30.19 The INFORMATION_SCHEMA INNODB_FT_DEFAULT_STOPWORD Table
- 20.30.20 The INFORMATION_SCHEMA INNODB_FT_INDEX_TABLE Table
- 20.30.21 The INFORMATION_SCHEMA INNODB_FT_INDEX_CACHE Table
- 20.30.22 The INFORMATION_SCHEMA INNODB_FT_DELETED Table
- 20.30.23 The INFORMATION_SCHEMA INNODB_FT_BEING_DELETED Table
The INNODB_CMP_PER_INDEX and
INNODB_CMP_PER_INDEX_RESET tables contain
status information on operations related to
compressed
InnoDB tables and indexes, with separate
statistics for each combination of database, table, and index, to
help you evaluate the performance and usefulness of compression
for specific tables.
For a compressed InnoDB table, both the table
data and all the secondary
indexes are compressed. In this context, the table data is
treated as just another index, one that happens to contain all the
columns: the clustered
index.
Table 20.2. Columns of INNODB_CMP_PER_INDEX and
INNODB_CMP_PER_INDEX_RESET
| Column name | Description |
|---|---|
DATABASE_NAME | Database containing the applicable table. |
TABLE_NAME | Table to monitor for compression statistics. |
INDEX_NAME | Index to monitor for compression statistics. |
COMPRESS_OPS | Number of compression operations attempted. Pages are compressed whenever an empty page is created or the space for the uncompressed modification log runs out. |
COMPRESS_OPS_OK | Number of successful compression operations. Subtract from the
COMPRESS_OPS value to get the number of
compression
failures. Divide by the COMPRESS_OPS
value to get the percentage of compression failures. |
COMPRESS_TIME | Total amount of CPU time, in seconds, used for compressing data in this index. |
UNCOMPRESS_OPS | Number of uncompression operations performed. Compressed
InnoDB pages are uncompressed whenever
compression
fails, or the
first time a compressed page is accessed in the
buffer pool and the
uncompressed page does not exist. |
UNCOMPRESS_TIME | Total amount of CPU time, in seconds, used for uncompressing data in this index. |
Notes:
Use these tables to measure the effectiveness of
InnoDBtable compression for specific tables, indexes, or both.You must have the
PROCESSprivilege to query these tables.Because collecting separate measurements for every index imposes substantial performance overhead, enable the
innodb_cmp_per_index_enabledconfiguration option before performing the operations on compressed tables that you want to monitor.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
InnoDBtable compression, see Section 5.4.6, “Working withInnoDBCompressed Tables”.
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