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Lefty Leverenz commented on HIVE-6430: -------------------------------------- This adds config parameter *hive.mapjoin.optimized.hashtable* to HiveConf.java but doesn't give a description in hive-default.xml.template or a HiveConf.java comment. HIVE-6037 is going to change HiveConf.java and start generating hive-default.xml.template from HiveConf.java, so I suggest putting the parameter description in a jira release note. Then it can be added to the new version of HiveConf.java after HIVE-6037 gets committed. > MapJoin hash table has large memory overhead > -------------------------------------------- > > Key: HIVE-6430 > URL: https://issues.apache.org/jira/browse/HIVE-6430 > Project: Hive > Issue Type: Improvement > Reporter: Sergey Shelukhin > Assignee: Sergey Shelukhin > Attachments: HIVE-6430.01.patch, HIVE-6430.02.patch, > HIVE-6430.03.patch, HIVE-6430.patch > > > Right now, in some queries, I see that storing e.g. 4 ints (2 for key and 2 > for row) can take several hundred bytes, which is ridiculous. I am reducing > the size of MJKey and MJRowContainer in other jiras, but in general we don't > need to have java hash table there. We can either use primitive-friendly > hashtable like the one from HPPC (Apache-licenced), or some variation, to map > primitive keys to single row storage structure without an object per row > (similar to vectorization). -- This message was sent by Atlassian JIRA (v6.2#6252)