Memory Optimization

If Machbase server process consumes too much memory, it slows down the entire performance of the system. In this case, it is safe to set a certain level of memory to be used even though some performance degradation is inevitable. Thus, tuning the system performance by using the properties below is necessary.

  • PROCESS_MAX_SIZE : This property specifies the maximum size of memory allocated by the Machbase server. The default value is set as 8G. If the server uses more memory than the value of this property, it waits until the memory is free. It is common to set this value to the limit of the physical memory of the server.

DISK_COLUMNAR_TABLESPACE_MEMORY_MAX_SIZE

This value is used to limit the amount of memory allocated to the log table. The default value is set to 4G. If disk I/O is slow and the memory allocated to the table grows larger than this property, append will temporarily stop. However, since the append will be resumed as soon as there is available memory, set this value appropriately.

DISK_COLUMNAR_TABLESPACE_MEMORY_SLOWDOWN_HIGH_LIMIT_PCT

This property slows down the pace of appending to the table if the allocated memory reaches a specific threshold before using them all of DISK_COLUMNAR_TABLESPACE_MEMORY_MAX_SIZE. The default value is 80.

For example,if the DISK_COLUMNAR_TABLESPACE_MEMORY_SLOWDOWN_HIGH_LIMIT_PCT is 80 and more than 80% of the DISK_COLUMNAR_TABLESPACE_MEMORY_MAX_SIZE has been used, it will slow down the process for a specified time in DISK_COLUMNAR_TABLESPACE_MEMORY_SLOWDOWN_MSEC only once before trying to append the data into the table.

If it exceeds DISK_COLUMNAR_TABLESPACE_MEMORY_MAX_SIZE, the append will pause until enough memory is available.

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