And assigns a cost to each plan, then determines the cheapest plan to execute a query. When false, the file size is fetched from the file system. The default setting for mapred.user.jobconf.limit is 5 MB. : Review the relevance of any safety valves (the non-default values for Hive and HiveServer2 configurations) for Hive and Hive on Tez. at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:1384) However you are manually set it to the number of reducer tasks (not recommended). 11-02-2017 Adding more reducers doesn't always guarantee better performance. See also How initial task parallelism works. What is Wario dropping at the end of Super Mario Land 2 and why? Should I re-do this cinched PEX connection? 2023 CBS Interactive Inc. All Rights Reserved. Typically set to a prime close to the number of available hosts. For users upgrading from HDP distribution, this discussion would also help to review and validate if the properties are correctly configured for performance in CDP. Before changing any configurations, you must understand the mechanics of how Tez works internally. This doesn't mean that number of partitions is equal to number of reducers. I need it for per join basis. What will happen if Hive number of reducers is different to number of keys? property in hive for setting size of reducer is : you can view this property by firing set command in hive cli. Please clarify. If you have 640MB file and Data Block size is 128 MB then we need to run 5 Mappers per MapReduce job. He also rips off an arm to use as a sword. at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:1388) Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, This will set it for all parts of the query rather than for a specific join. 02-07-2019 at java.lang.reflect.Method.invoke(Method.java:611) Is "I didn't think it was serious" usually a good defence against "duty to rescue"? The reducer which gets the 2 partitions will process one partition after the another. works will help you optimize the query performance. IOException: Exceeded max jobconf size: 7374812 limit: 5242880 You can modify using set mapred.map.tasks =