default void preDropPartitions(Table table,
      EnvironmentContext context, List<Pair<Integer, byte[]>> partExprs) throws MetaException {
    // Do nothing
  }
Called before dropping the partitions from the table in the metastore during ALTER TABLE DROP PARTITION.
@param table table whose partition needs to be dropped
@param context context of the  operation
@param partExprs List of partition expressions
@throws MetaException
standalone-metastore/metastore-common/src/main/java/org/apache/hadoop/hive/metastore/HiveMetaHook.java