What's New in Apache Hive

Learn about the new features of Hive in Cloudera Runtime 7.2.18.

HiveServer graceful shutdown

You can now configure the graceful shutdown timeout property for HiveServer (HS2), which ensures that HS2 waits for a specified time period before shutting down, thereby allowing queries that are already running to complete before HS2 stops. For more information, see Configuring graceful shutdown property for HiveServer.

Support for column histogram statistics

In this release, when you generate column statistics in Hive, you can create histogram statistics on columns. By default, the histogram stats are not created. You enable generation of histogram statistics by setting a Hive property: set hive.stats.kll.enable = true;

You can then run the ANALYZE command as usual:

ANALYZE TABLE [table_name] COMPUTE STATISTICS for COLUMNS [comma_separated_column_list];

Histogram statistics are supported for numeric data types, date, timestamp and boolean types but not for string/varchar/char columns. Histograms are used to estimate selectivity of range predicates (predicates involving <, <=, >, >= and BETWEEN). The better selectivity estimate allows the optimizer to generate more optimal query plans and improve performance for such queries.