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- The compactor (for use with ACID tables) cannot be run without Hive. ACID tables can be read and written to, but they cannot compacted.
- Replication has not been tested outside of Hive.
Performance Optimizations
CachedStore
Prior to Hive 3.0 there was only a single implementation of the MetaStore API (called ObjectStore). HIVE-16520 introduced a second implementation that can cache objects from the database in memory. This can save a significant amount of time for round trips to the database. It can be used by changing the parameter metastore.rawstore.impl to org.apache.hadoop.hive.metastore.cache.CachedStore.
The cache is automatically updated with new data when changes are made through this MetaStore. In a scenario where there are multiple MetaStore servers the caches can be out of date on some of them. To prevent this the CachedStore automatically refreshes the cache in a configurable frequency (default: 1 minute).
Details about all properties for the CachedStore can be found on Configuration Properties (Prefix: metastore.cached).
Less Commonly Changed Configuration Parameters
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