$ hive --version

CREATE TABLE person20(
  persid int,
  lastname string,
  firstname string)
CLUSTERED BY (
  persid)
INTO 1 BUCKETS
ROW FORMAT SERDE
  'org.apache.hadoop.hive.ql.io.orc.OrcSerde'
STORED AS INPUTFORMAT
  'org.apache.hadoop.hive.ql.io.orc.OrcInputFormat'
OUTPUTFORMAT
  'org.apache.hadoop.hive.ql.io.orc.OrcOutputFormat'
LOCATION
  'hdfs://hostname.com:8020/user/hive/warehouse/person20'
TBLPROPERTIES (
  'COLUMN_STATS_ACCURATE'='true',
  'numFiles'='3',
  'numRows'='2',
  'rawDataSize'='348',
  'totalSize'='1730',
  'transactional'='true',
  'transient_lastDdlTime'='1489668385')

INSERT INTO TABLE person20 VALUES (0,'PP','B'),(2,'X','Y');

set hive.cli.print.header=true;

select * from person20;

persid lastname  firstname
2       X       Y
0       PP      B

CREATE TABLE person21(
  persid int,
  lastname string,
  firstname string)
ROW FORMAT SERDE
  'org.apache.hadoop.hive.serde2.lazy.LazySimpleSerDe'
STORED AS INPUTFORMAT
  'org.apache.hadoop.mapred.TextInputFormat'
OUTPUTFORMAT
  'org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat'
LOCATION
  'hdfs://hostname.com:8020/user/hive/warehouse/person21'
TBLPROPERTIES (
  'COLUMN_STATS_ACCURATE'='true',
  'numFiles'='1',
  'numRows'='2',
  'rawDataSize'='11',
  'totalSize'='13',
  'transient_lastDdlTime'='1489668344')

INSERT INTO TABLE person20 VALUES (0,'SS','B'),(2,'X','Y');

select * from person21;

persid lastname firstname
2       X1       Y
0       SS       B

Merge into  person20 p20 USING person21 p21
ON (p20.persid=p21.persid)
WHEN MATCHED THEN
UPDATE set p20.lastname=p21.lastname

hive -e "set hive.auto.convert.join.noconditionaltask.size = 10000000; set hive.support.concurrency = true; set hive.enforce.bucketing = true; set hive.exec.dynamic.partition.mode = nonstrict; set hive.txn.manager = org.apache.hadoop.hive.ql.lockmgr.DbTxnManager; set hive.compactor.initiator.on = true;
set hive.compactor.worker.threads = 1 ; UPDATE person20 SET lastname = (select lastname from person21 where person21.lastname=person20.lastname);"

hive -e "set hive.auto.convert.join.noconditionaltask.size = 10000000; set hive.support.concurrency = true; set hive.enforce.bucketing = true; set hive.exec.dynamic.partition.mode = nonstrict; set hive.txn.manager = org.apache.hadoop.hive.ql.lockmgr.DbTxnManager; set hive.compactor.initiator.on = true;
set hive.compactor.worker.threads = 1 ; UPDATE person20 SET lastname = 'PP' WHERE  persid = 0;"