1 hive version [hadoop@gxdh01 ~]$ hive --version Hive 1.1.0-cdh5.7.5 Subversion file:///data/jenkins/workspace/generic-package-rhel64-6-0/topdir/BUILD/hive-1.1.0-cdh5.7.5 -r Unknown Compiled by jenkins on Wed Nov 2 11:53:22 PDT 2016 From source with checksum 0e57e48866fa2d9aa5d36cca7bffae5e   2 when I do a hive inner join query ,a timestamp columns's value added by an hour. hive> SELECT COMMUNITY_ID, BUILDENDDATE > FROM DW_ODS.ODS_COMMUNITY A > WHERE A.DAY_ID = '20170324' > AND COMMUNITY_ID = 5086560 > ; Query ID = hadoop_20170328085656_331bf931-3ad9-4162-9a1a-89e46586ccef Total jobs = 1 Launching Job 1 out of 1 Number of reduce tasks is set to 0 since there's no reduce operator Starting Job = job_1490177280986_5130, Tracking URL = http://gxdh01:8088/proxy/application_1490177280986_5130/ Kill Command = /opt/cloudera/parcels/CDH-5.7.5-1.cdh5.7.5.p0.3/lib/hadoop/bin/hadoop job -kill job_1490177280986_5130 Hadoop job information for Stage-1: number of mappers: 4; number of reducers: 0 2017-03-28 08:56:16,231 Stage-1 map = 0%, reduce = 0% 2017-03-28 08:56:22,409 Stage-1 map = 75%, reduce = 0%, Cumulative CPU 6.4 sec 2017-03-28 08:56:24,460 Stage-1 map = 100%, reduce = 0%, Cumulative CPU 10.07 sec MapReduce Total cumulative CPU time: 10 seconds 70 msec Ended Job = job_1490177280986_5130 MapReduce Jobs Launched: Stage-Stage-1: Map: 4 Cumulative CPU: 10.07 sec HDFS Read: 494905939 HDFS Write: 28 SUCCESS Total MapReduce CPU Time Spent: 10 seconds 70 msec OK 5086560 1971-01-01 00:00:00 Time taken: 14.011 seconds, Fetched: 1 row(s) hive> you can see BUILDENDDATE's value is 1971-01-01 00:00:00   you can see BUILDENDDATE's value is 1971-01-01 00:00:00   when I do a inner join hive> SELECT T1.COMMUNITY_ID, T1.BUILDENDDATE > FROM (SELECT * > FROM DW_ODS.ODS_COMMUNITY A > WHERE A.DAY_ID = '20170324' > AND COMMUNITY_ID = 5086560) T1 > INNER JOIN (SELECT ADDRESS_ID > FROM DW_ODS.ODS_STREET_NUMBER SN > WHERE DAY_ID = '20170324') T2 > ON T1.COMMUNITY_ID = T2.ADDRESS_ID; Query ID = hadoop_20170328085858_57223eaf-6b40-407d-8ec9-4212f1db0668 Total jobs = 1 Stage-1 is selected by condition resolver. Launching Job 1 out of 1 Number of reduce tasks not specified. Estimated from input data size: 12 In order to change the average load for a reducer (in bytes): set hive.exec.reducers.bytes.per.reducer=<number> In order to limit the maximum number of reducers: set hive.exec.reducers.max=<number> In order to set a constant number of reducers: set mapreduce.job.reduces=<number> Starting Job = job_1490177280986_5131, Tracking URL = http://gxdh01:8088/proxy/application_1490177280986_5131/ Kill Command = /opt/cloudera/parcels/CDH-5.7.5-1.cdh5.7.5.p0.3/lib/hadoop/bin/hadoop job -kill job_1490177280986_5131 Hadoop job information for Stage-1: number of mappers: 8; number of reducers: 12 2017-03-28 08:58:16,658 Stage-1 map = 0%, reduce = 0% 2017-03-28 08:58:22,817 Stage-1 map = 38%, reduce = 0%, Cumulative CPU 6.99 sec 2017-03-28 08:58:23,843 Stage-1 map = 75%, reduce = 0%, Cumulative CPU 18.22 sec 2017-03-28 08:58:24,867 Stage-1 map = 100%, reduce = 0%, Cumulative CPU 27.43 sec 2017-03-28 08:58:29,994 Stage-1 map = 100%, reduce = 83%, Cumulative CPU 52.4 sec 2017-03-28 08:58:31,018 Stage-1 map = 100%, reduce = 100%, Cumulative CPU 58.12 sec MapReduce Total cumulative CPU time: 58 seconds 120 msec Ended Job = job_1490177280986_5131 MapReduce Jobs Launched: Stage-Stage-1: Map: 8 Reduce: 12 Cumulative CPU: 58.12 sec HDFS Read: 743128560 HDFS Write: 84 SUCCESS Total MapReduce CPU Time Spent: 58 seconds 120 msec OK 5086560 1971-01-01 01:00:00 5086560 1971-01-01 01:00:00 5086560 1971-01-01 01:00:00 Time taken: 19.316 seconds, Fetched: 3 row(s) hive> you can see the column's value of BUILDENDDATE added by an hour,orignal value is 1971-01-01 00:00:00,but inner join's value is 1971-01-01 01:00:00 please help me,thanks! why? ... View more