Adjusting Metadata Cache

Scenario

When HetuEngine accesses the Hive data source, it needs to access the Hive metastore to obtain the metadata information. HetuEngine provides the metadata cache function. When the database or table of the Hive data source is accessed for the first time, the metadata information (database name, table name, table field, partition information, and permission information) of the database or table is cached, the Hive metastore does not need to be accessed again during subsequent access. If the table data of the Hive data source does not change frequently, the query performance can be improved to some extent.

Procedure

1. Log in to FusionInsight Manager.
2. Choose Cluster > Services > HetuEngine > Configurations > All Configurations and adjust the metadata cache parameters by referring to Table 1.

   Table 1 Metadata cache parameters

   Parameter	Description	Default Value	Parameter File
   hive.metastore-cache-ttl	Cache duration of the metadata of the co-deployed Hive data source.	0s	hive.properties
   hive.metastore-cache-maximum-size	Maximum cache size of the metadata of the co-deployed Hive data source.	10000	hive.properties
   hive.metastore-refresh-interval	Interval for refreshing the metadata of the co-deployed Hive data source.	1s	hive.properties
   hive.per-transaction-metastore-cache-maximum-size	Maximum cache size of the metadata for each transaction of the co-deployed Hive data source.	1000	hive.properties

3. Click Save.
4. Choose Cluster > Services > HetuEngine > More > Restart Service to restart the HetuEngine service for the parameters to take effect.