Performance Schema table_io_waits_summary_by_index_usage Table

MariaDB starting with 10.0

The table_io_waits_summary_by_index_usage table, along with many other new Performance Schema tables, was added in MariaDB 10.0.

The table_io_waits_summary_by_index_usage table records table I/O waits by index.

ColumnDescription
OBJECT_TYPETABLE in the case of all indexes.
OBJECT_SCHEMASchema name.
OBJECT_NAMETable name.
INDEX_NAMEIndex name, or PRIMARY for the primary index, NULL for no index (inserts are counted in this case).
COUNT_STARNumber of summarized events and the sum of the x_READ and x_WRITE columns.
SUM_TIMER_WAITTotal wait time of the summarized events that are timed.
MIN_TIMER_WAITMinimum wait time of the summarized events that are timed.
AVG_TIMER_WAITAverage wait time of the summarized events that are timed.
MAX_TIMER_WAITMaximum wait time of the summarized events that are timed.
COUNT_READNumber of all read operations, and the sum of the equivalent x_FETCH columns.
SUM_TIMER_READTotal wait time of all read operations that are timed.
MIN_TIMER_READMinimum wait time of all read operations that are timed.
AVG_TIMER_READAverage wait time of all read operations that are timed.
MAX_TIMER_READMaximum wait time of all read operations that are timed.
COUNT_WRITENumber of all write operations, and the sum of the equivalent x_INSERT, x_UPDATE and x_DELETE columns.
SUM_TIMER_WRITETotal wait time of all write operations that are timed.
MIN_TIMER_WRITEMinimum wait time of all write operations that are timed.
AVG_TIMER_WRITEAverage wait time of all write operations that are timed.
MAX_TIMER_WRITEMaximum wait time of all write operations that are timed.
COUNT_FETCHNumber of all fetch operations.
SUM_TIMER_FETCHTotal wait time of all fetch operations that are timed.
MIN_TIMER_FETCHMinimum wait time of all fetch operations that are timed.
AVG_TIMER_FETCHAverage wait time of all fetch operations that are timed.
MAX_TIMER_FETCHMaximum wait time of all fetch operations that are timed.
COUNT_INSERTNumber of all insert operations.
SUM_TIMER_INSERTTotal wait time of all insert operations that are timed.
MIN_TIMER_INSERTMinimum wait time of all insert operations that are timed.
AVG_TIMER_INSERTAverage wait time of all insert operations that are timed.
MAX_TIMER_INSERTMaximum wait time of all insert operations that are timed.
COUNT_UPDATENumber of all update operations.
SUM_TIMER_UPDATETotal wait time of all update operations that are timed.
MIN_TIMER_UPDATEMinimum wait time of all update operations that are timed.
AVG_TIMER_UPDATEAverage wait time of all update operations that are timed.
MAX_TIMER_UPDATEMaximum wait time of all update operations that are timed.
COUNT_DELETENumber of all delete operations.
SUM_TIMER_DELETETotal wait time of all delete operations that are timed.
MIN_TIMER_DELETEMinimum wait time of all delete operations that are timed.
AVG_TIMER_DELETEAverage wait time of all delete operations that are timed.
MAX_TIMER_DELETEMaximum 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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