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• Default Value: true
• Added In: Hive 0.13.0 with HIVE-6429 and HIVE-6188
• Removed In: Hive 1.1.0 with HIVE-9331

Whether a MapJoin hashtable should use optimized (size-wise) keys, allowing the table to take less memory. Depending on the key, memory savings for the entire table can be 5-15% or so.

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• Default Value: true
• Added In: Hive 0.13.0 with HIVE-6418 and HIVE-6188
• Removed In: Hive 1.1.0 with HIVE-9331

Whether a MapJoin hashtable should deserialize values on demand. Depending on how many values in the table the join will actually touch, it can save a lot of memory by not creating objects for rows that are not needed. If all rows are needed, obviously there's no gain.

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hive.exec.reducers.bytes.per.reducer, hive.exec.reducers.max, hive.map.aggr, hive.map.aggr.hash.percentmemory, hive.map.aggr.hash.force.flush.memory.threshold, hive.map.aggr.hash.min.reduction, hive.groupby.skewindata, hive.optimize.multigroupby.common.distincts, hive.optimize.index.groupby, hive.optimize.ppd, hive.optimize.ppd.storage, hive.ppd.recognizetransivity, hive.optimize.groupby, hive.optimize.sort.dynamic.partition, hive.optimize.union.remove, hive.multigroupby.singlereducer, hive.map.groupby.sorted, hive.map.groupby.sorted.testmode, hive.optimize.skewjoin, hive.optimize.skewjoin.compiletime, hive.mapred.mode, hive.enforce.bucketmapjoin, hive.exec.compress.output, hive.exec.compress.intermediate, hive.exec.parallel, hive.exec.parallel.thread.number, hive.exec.rowoffset, hive.merge.mapfiles, hive.merge.mapredfiles, hive.merge.tezfiles, hive.ignore.mapjoin.hint, hive.auto.convert.join, hive.auto.convert.join.noconditionaltask, hive.auto.convert.join.noconditionaltask.size, hive.auto.convert.join.use.nonstaged, hive.enforce.bucketing, hive.enforce.sorting, hive.enforce.sortmergebucketmapjoin, hive.auto.convert.sortmerge.join, hive.execution.engine, hive.vectorized.execution.enabled, hive.mapjoin.optimized.keys, hive.mapjoin.lazy.hashtable, hive.exec.check.crossproducts, hive.compat, hive.exec.dynamic.partition.mode, mapred.reduce.tasks, mapred.output.compression.codec, mapred.map.output.compression.codec, mapreduce.job.reduce.slowstart.completedmaps, mapreduce.job.queuename.

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Some parameters are added automatically when they match one of the regex specifications for the white list in HiveConf.java (for example, hive.log.trace.id in release Hive 2.0.0 – see HIVE-12419).

Note that the hive.conf.restricted.list checks are still enforced after the white list check.

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For WebHCat configuration, see Configuration Variables in the WebHCat manual.