@Override
  /**
   * getPartitionSpecsByFilterAndProjection interface is currently non-cacheable.
   */ public List<Partition> getPartitionSpecsByFilterAndProjection(Table table,
      GetProjectionsSpec projectionSpec, GetPartitionsFilterSpec filterSpec)
      throws MetaException, NoSuchObjectException {
    return rawStore.getPartitionSpecsByFilterAndProjection(table, projectionSpec, filterSpec);
  }
This starts a background thread, which initially populates the SharedCache and later
periodically gets updates from the metastore db

@param conf
@param runOnlyOnce
@param shouldRunPrewarm
standalone-metastore/metastore-server/src/main/java/org/apache/hadoop/hive/metastore/cache/CachedStore.java