Spec-Zone .ru
спецификации, руководства, описания, API
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Spec-Zone .ru
спецификации, руководства, описания, API
|
The INNODB_SYS_TABLESTATS view provides status information about performance
statistics for InnoDB tables. These statistics represent low-level information used
by the MySQL optimizer to calculate which index to use when querying an InnoDB
table. This information is derived from in-memory data structures rather than corresponding to data stored on
disk.
InnoDB tables are represented in this view if they have been opened since the last
server restart, and not aged out of the table cache. Tables for which persistent stats are available are always
represented in this view.
Table 20.13. INNODB_SYS_TABLESTATS Columns
| Column name | Description |
|---|---|
TABLE_ID |
An identifier representing the table for which statistics are available, using the same value as
INNODB_SYS_TABLES.TABLE_ID.
|
NAME |
The name of the table, using the same value as INNODB_SYS_TABLES.NAME.
|
STATS_INITIALIZED |
The value is Initialized if the statistics are already collected,
Uninitialized if not.
|
NUM_ROWS |
The current estimated number of rows in the table. Updated after each DML operation. Could be imprecise if uncommitted transactions are inserting into or deleting from the table. |
CLUST_INDEX_SIZE |
Number of pages on disk that store the clustered index, which holds the InnoDB
table data in primary key order. This value might be null if no statistics are collected yet for
the table.
|
OTHER_INDEX_SIZE |
Number of pages on disk that store all secondary indexes for the table. This value might be null if no statistics are collected yet for the table. |
MODIFIED_COUNTER |
The number of rows modified by DML operations, such as INSERT,
UPDATE, DELETE, and also cascade
operations from foreign keys.
|
AUTOINC |
|
REF_COUNT |
When this counter reaches zero, the table metadata can be evicted fromthe table cache. |
Notes:
This table is primarily useful for expert-level performance monitoring, or when developing performance-related extensions for MySQL.
Since the INFORMATION_SCHEMA is a general-purpose way
to monitor the MySQL server, use this table rather than the corresponding InnoDB system table for any new monitoring application you develop.
You must have the PROCESS privilege to query this
table.