memstore_limit_percentage

Purpose

memstore_limit_percentage specifies the percentage of the memory that can be occupied by MemStores to the total available memory of a tenant.

Attributes

Considerations

• The memstore_limit_percentage parameter is used to calculate the value of memstore_limit by using the following formula:

  memstore_limit_percentage = memstore_limit/memory_size

  In the formula, memory_size indicates the total available memory of the tenant and is specified during tenant creation. For more information about memstore_limit, see memstore_limit.

• OceanBase Database V4.3.0 and later allow you to use the tenant-level hidden parameter _memstore_limit_percentage to specify the percentage of the memory that can be occupied by MemStores to the total available memory of a tenant. Except for the effective scope, its feature and default value are the same as those of the cluster-level parameter memstore_limit_percentage. When you specify the two parameters, take note of the following considerations:

• If you specify a value other than the default value only for _memstore_limit_percentage or memstore_limit_percentage, the specified value prevails.
• If you specify values, other than the default values, for both the tenant-level hidden parameter _memstore_limit_percentage and the cluster-level parameter memstore_limit_percentage, the value of _memstore_limit_percentage prevails.
• If neither parameter is specified or the default values are used for both parameters, the system complies with the following rules:
  • For a tenant with 8 GB of memory or less, the percentage of memory that can be occupied by MemStores is 40%.
  • For a tenant with more than 8 GB of memory, the percentage of memory that can be occupied by MemStores is 50%.

Examples

obclient> ALTER SYSTEM SET memstore_limit_percentage = 60;

References

• Minor compaction and major compaction
• Modify minor compaction settings
• Tenant memory full
• Manage internal tenant memory