storage_meta_cache_priority

Description

storage_meta_cache_priority specifies the priority of the storage meta cache in the kvcache.

Privilege requirements

• Query the parameter

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

• Modify the parameter

  Only the sys tenant can modify this parameter. User tenants cannot modify this parameter.

Attributes

Considerations

OceanBase Database abstracts the metadata of Table Store, SSTable, and other data types into storage meta data and stores the storage meta data in the kvcache. When the usage of the storage meta cache is low or the cache frequently misses, you can change the priority of the cache based on the load characteristics to improve the utilization of the limited kvcache memory resources and make them more flexible.

In the kvcache, the higher the priority value of a cache, the higher its priority and the less likely it is to be evicted from memory. The following table lists the priority parameters of the existing cache types:

• tablet_ls_cache_priority: The default value is 1000, and the value range is [1, +∞).

• opt_tab_stat_cache_priority: The default value is 1, and the value range is [1, +∞).

• index_block_cache_priority: The default value is 10, and the value range is [1, +∞).

• user_block_cache_priority: The default value is 1, and the value range is [1, +∞).

• user_row_cache_priority: The default value is 1, and the value range is [1, +∞).

• bf_cache_priority: The default value is 1, and the value range is [1, +∞).

• fuse_row_cache_priority: The default value is 1, and the value range is [1, +∞).

The default value of the storage meta cache priority is the same as that of the index_block_cache_priority parameter and is the second highest after the tablet_ls_cache_priority parameter.

Examples

Set the priority of the storage meta cache in the kvcache to 10.

obclient> ALTER SYSTEM SET storage_meta_cache_priority='10';