sql:insert into tableとinsert overwrite tableの違い

テスト結果をテストするテストテーブルを作成します.

create table test(name string,pwd string,createdate string)row format delimited fields terminated by ',';

ステップ1:insert intoを使用してテーブルにデータを挿入します.

insert into test(name,pwd,createdate)values('name1','pwd1','2017-06-20 14:14:09');
insert into test(name,pwd,createdate)values('name1','pwd1','2017-06-20 14:14:09');
insert into test(name,pwd,createdate)values('name2','pwd2','2017-06-20 14:14:09');
insert into test(name,pwd,createdate)values('name2','pwd2','2017-06-20 14:14:09');
0: jdbc:hive2://10.78.152.52:21066/> select * from test;
+------------+-----------+----------------------+--+
| test.name  | test.pwd  |   test.createdate    |
+------------+-----------+----------------------+--+
| name1      | pwd1      | 2017-06-20 14:14:09  |
| name1      | pwd1      | 2017-06-20 14:14:09  |
| name2      | pwd2      | 2017-06-20 14:14:09  |
| name2      | pwd2      | 2017-06-20 14:14:09  |
+------------+-----------+----------------------+--

ステップ2:上記の挿入レコードをクリーンアップせずにinsert overwirteを直接実行し、分析結果をクエリーします.

insert overwrite table test select 'name1' as name,'pwd1' as pwd,'2017-06-20 14:14:09' as createdate;
insert overwrite table test select 'name2' as name,'pwd2' as pwd,'2017-06-20 14:14:09' as createdate;
insert overwrite table test select 'name2' as name,'pwd2' as pwd,'2017-06-20 14:14:09' as createdate;
insert overwrite table test select 'name3' as name,'pwd3' as pwd,'2017-06-20 14:14:09' as createdate;
0: jdbc:hive2://10.78.152.62:21066/> select * from test;
+------------+-----------+----------------------+--+
| test.name  | test.pwd  |   test.createdate    |
+------------+-----------+----------------------+--+
| name3      | pwd3      | 2017-06-20 14:14:09  |
+------------+-----------+----------------------+--+

ステップ3:前のステップで実行した結果をクリーンアップしないで、次のsql文を実行し、結果をクエリーします.

insert overwrite table test select 'name2' as name,'pwd2' as pwd,'2017-06-20 14:14:09' as createdate;
0: jdbc:hive2://10.78.152.62:21066/> select * from test;
+------------+-----------+----------------------+--+
| test.name  | test.pwd  |   test.createdate    |
+------------+-----------+----------------------+--+
| name2      | pwd2      | 2017-06-20 14:14:09  |
+------------+-----------+----------------------+--+