Setting Cache Flushing to Drives for Operators
When the Agg, HashJoin, Sort, and Materialize operators cache a large amount of data, you can adjust the cache-flushing parameters for operators to improve the success rate of parallel queries.
KOVAE's default drive cache file directory is the directory displayed in the value of the tmpdir parameter. This parameter can only be configured in the configuration file or by modifying the MySQL service command line parameter. It cannot be dynamically modified when MySQL is running.
KOVAE has the Agg, HashJoin, Sort, and Materialize operators, which support the mechanism of triggering cache flushing when the cache exceeds the configured value. kovae_memory_buffer_size is the threshold configuration parameter related to operator cache flushing. For details, see Setting and Querying KOVAE Parameters and Querying Status Variables.
Procedure
- Log in to the MySQL service through the MySQL client.
- Set KOVAE parameters.
set variable Parameter_name=Parameter_value; set global variable Parameter_name=Parameter_value;
- Check the configured parameters.
show variables like "%Parameter_name%";