Performance Schema table_io_waits_summary_by_index_usage Table
The table_io_waits_summary_by_index_usage table records table I/O waits by index.
| Column | Description |
|---|---|
OBJECT_TYPE | TABLE in the case of all indexes. |
OBJECT_SCHEMA | Schema name. |
OBJECT_NAME | Table name. |
INDEX_NAME | Index name, or PRIMARY for the primary index, NULL for no index (inserts are counted in this case). |
COUNT_STAR | Number of summarized events and the sum of the x_READ and x_WRITE columns. |
SUM_TIMER_WAIT | Total wait time of the summarized events that are timed. |
MIN_TIMER_WAIT | Minimum wait time of the summarized events that are timed. |
AVG_TIMER_WAIT | Average wait time of the summarized events that are timed. |
MAX_TIMER_WAIT | Maximum wait time of the summarized events that are timed. |
COUNT_READ | Number of all read operations, and the sum of the equivalent x_FETCH columns. |
SUM_TIMER_READ | Total wait time of all read operations that are timed. |
MIN_TIMER_READ | Minimum wait time of all read operations that are timed. |
AVG_TIMER_READ | Average wait time of all read operations that are timed. |
MAX_TIMER_READ | Maximum wait time of all read operations that are timed. |
COUNT_WRITE | Number of all write operations, and the sum of the equivalent x_INSERT, x_UPDATE and x_DELETE columns. |
SUM_TIMER_WRITE | Total wait time of all write operations that are timed. |
MIN_TIMER_WRITE | Minimum wait time of all write operations that are timed. |
AVG_TIMER_WRITE | Average wait time of all write operations that are timed. |
MAX_TIMER_WRITE | Maximum wait time of all write operations that are timed. |
COUNT_FETCH | Number of all fetch operations. |
SUM_TIMER_FETCH | Total wait time of all fetch operations that are timed. |
MIN_TIMER_FETCH | Minimum wait time of all fetch operations that are timed. |
AVG_TIMER_FETCH | Average wait time of all fetch operations that are timed. |
MAX_TIMER_FETCH | Maximum wait time of all fetch operations that are timed. |
COUNT_INSERT | Number of all insert operations. |
SUM_TIMER_INSERT | Total wait time of all insert operations that are timed. |
MIN_TIMER_INSERT | Minimum wait time of all insert operations that are timed. |
AVG_TIMER_INSERT | Average wait time of all insert operations that are timed. |
MAX_TIMER_INSERT | Maximum wait time of all insert operations that are timed. |
COUNT_UPDATE | Number of all update operations. |
SUM_TIMER_UPDATE | Total wait time of all update operations that are timed. |
MIN_TIMER_UPDATE | Minimum wait time of all update operations that are timed. |
AVG_TIMER_UPDATE | Average wait time of all update operations that are timed. |
MAX_TIMER_UPDATE | Maximum wait time of all update operations that are timed. |
COUNT_DELETE | Number of all delete operations. |
SUM_TIMER_DELETE | Total wait time of all delete operations that are timed. |
MIN_TIMER_DELETE | Minimum wait time of all delete operations that are timed. |
AVG_TIMER_DELETE | Average wait time of all delete operations that are timed. |
MAX_TIMER_DELETE | Maximum wait time of all delete operations that are timed. |
You can TRUNCATE the table, which will reset all counters to zero. The table is also truncated if the table_io_waits_summary_by_table table is truncated.
If a table's index structure is changed, index statistics recorded in this table may also be reset.
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