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Release 1.7 (2023-5-15)

MR3​

  • Support standalone mode which does not require Yarn or Kubernetes as the resource manager.

Hive on MR3​

  • Use Hadoop 3.3.1.
  • hive.query.reexecution.stats.persist.scope can be set to hiveserver.
  • HIVE_JVM_OPTION in env.sh specifies the JMV options for Metastore and HiveServer2.
  • Do not use TEZ_USE_MINIMAL in env.sh.

Support for standalone mode​

MR3 supports standalone mode in which the user manually executes DAGAppMaster and ContainerWorkers, rather than relying on the underlying resource manager such as Hadoop or Kubernetes. In standalone mode, installing Hive on MR3 is just as easy as installing Presto or Trino.

Support for Java 11 and higher​

Java is evolving fast, but MR3 still requires Java 8. On Hadoop, it is not easy to migrate to a higher version such as Java 11 because of potential dependency problems. On Kubernetes, however, it suffices to check dependency problems in a local cluster. Thus we plan to upgrade MR3 to use Java 11 or higher, and experiment with it on Kubernetes. In particular, new garbage collectors available in recent versions of Java (such as Shenandoah and ZGC) may be able to instantly boost the performance of MR3 for free.