ob_vector_index_active_segment_max_size

Description

ob_vector_index_active_segment_max_size specifies the maximum memory usage of an active segment in a partition. When the memory usage of the active segment exceeds this threshold, the system triggers a freeze and persistence operation to write the incremental data in memory to disk.

Privilege requirements

• Query the parameter

  The sys tenant and MySQL user tenants can query the parameter by using the SHOW PARAMETERS statement or the GV$OB_PARAMETERS view.

• Modify the parameter

  The sys tenant and MySQL user tenants can modify the parameter.

Attributes

Considerations

• Increase the threshold: This reduces the frequency of freezing, thereby avoiding the creation of excessive active segments during high-speed incremental writes, which can degrade search performance.
• Decrease the threshold: We recommend that you do not decrease the threshold in most scenarios. Frequent freezing operations can degrade overall search performance.
• Restart the database: If the threshold is too large, the system will take a longer time to restore memory data during a restart. We recommend that you decrease the threshold before a restart to reduce the time required for memory data restoration. Alternatively, you can restart the database during off-peak hours.

Examples

Set the maximum memory usage of an active segment in a partition to 256 MB.

ALTER SYSTEM SET ob_vector_index_active_segment_max_size = '256MB';

Query the current configuration.

SHOW PARAMETERS LIKE 'ob_vector_index_active_segment_max_size';

References

• Vector index memory management
• Vector index principles