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 use the SHOW PARAMETERS statement or the GV$OB_PARAMETERS view to query this parameter.

• Modify the parameter

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

Attributes

Considerations

OceanBase Database abstracts metadata such as Table Store and SSTables into storage meta and manages it in the kvcache. When the usage of the meta cache is low or when the cache frequently misses, you can change the priority of the cache based on the workload characteristics to improve the efficiency of the limited kvcache memory resources and make them more flexible.

In the kvcache, a higher priority value indicates a higher priority and less likelihood of being evicted from memory. The following table lists the priority parameters for different cache types:

• tablet_ls_cache_priority, which has a default value of 1000 and a value range of [1, +∞).

• opt_tab_stat_cache_priority, which has a default value of 1 and a value range of [1, +∞).

• index_block_cache_priority, which has a default value of 10 and a value range of [1, +∞).

• user_block_cache_priority, which has a default value of 1 and a value range of [1, +∞).

• user_row_cache_priority, which has a default value of 1 and a value range of [1, +∞).

• bf_cache_priority, which has a default value of 1 and a value range of [1, +∞).

• fuse_row_cache_priority, which has a default value of 1 and a value range of [1, +∞).

Note that the default value of the storage meta cache priority is the same as that of index_block_cache_priority, which is the second highest after tablet_ls_cache_priority.

Examples

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

obclient> ALTER SYSTEM SET storage_meta_cache_priority='10';