hive-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "r7raul1984@163.com" <r7raul1...@163.com>
Subject Re: Re: sql mapjoin very slow
Date Fri, 28 Aug 2015 01:51:21 GMT
I use MR. 
My mapjoin config as showed in follow picture:



r7raul1984@163.com
 
From: Sergey Shelukhin
Date: 2015-08-28 09:21
To: user
Subject: Re: sql mapjoin very slow
Are you using MR and Tez? You could try optimized hash table in case of Tez, although it’s
supposed to improve memory, not necessarily perf.

Can you also share characteristics of the query and data? It is surprising to see so much
time for HashMap.get.

From: "r7raul1984@163.com" <r7raul1984@163.com>
Reply-To: user <user@hive.apache.org>
Date: Thursday, August 27, 2015 at 18:03
To: user <user@hive.apache.org>
Subject: sql mapjoin very slow


When I enable mapjoin ,I see Mapjoin task run very slow. My envrioment is hadoop 2.3.0 hive
1.1.0.

My attach is  one map hive log and this map's xprof log.

In map xprof log ,I see 
Compiled + native Method 
92.3% 643527 + 0 java.util.HashMap.get 
2.8% 19856 + 0 java.util.HashMap.put 
1.2% 8623 + 0 org.apache.hadoop.hive.ql.exec.persistence.HashMapWrapper$GetAdaptor.setFromRow

0.1% 953 + 0 org.apache.hadoop.hive.ql.exec.ExprNodeColumnEvaluator._evaluate 
0.1% 576 + 0 org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorUtils.copyToStandardObject



r7raul1984@163.com
Mime
View raw message