how can we rename multiple partitions in Hive? - hive

Question

If have two partitioned columns for eg. school name and class
How can I rename a specific class partition which is present inside all school partitions
so,
/school=ABC/class=1/
/school=PQR/class=1/
.
.
.
.
class = 1 should be transformed to class = 2
/school=ABC/class=2/
/school=PQR/class=2/
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Edit: In this example there are only two schools but it is variable there could be thousands of schools.

Answer 1

If table is managed table, you can simply use below command to rename the partition,
alter table tbl_name PARTITION (school='ABC', class=1) RENAME TO
PARTITION (school='ABC', class=2);
alter table tbl_name PARTITION (school='PQR', class=1) RENAME TO
PARTITION (school='PQR', class=2);
Below is execution I tried in hive,
hive> create table tbl_name (
name string,
age int)
partitioned by (school string, class int);
hive> alter table tbl_name ADD PARTITION (school='ABC', class=1); OK
Time taken: 0.157 seconds
hive> alter table tbl_name ADD PARTITION (school='PQR', class=1); OK
Time taken: 0.128 seconds
hive> show partitions tbl_name; OK school=ABC/class=1
school=PQR/class=1
hive> alter table tbl_name PARTITION (school='ABC', class=1) RENAME TO
PARTITION (school='ABC', class=2); OK Time taken: 0.468 seconds
hive> alter table tbl_name PARTITION (school='PQR', class=1) RENAME TO
PARTITION (school='PQR', class=2); OK Time taken: 0.432 seconds
hive> show partitions tbl_name; OK school=ABC/class=2
school=PQR/class=2
Hope this will help.

Answer 2

You can try getting the partition information from metadata.
1> get the metadata information from hive-site.xml file (location: /hive/installation/location/hive/hive-2.1/conf)
2> Get the env and credentials
<property>
<name>javax.jdo.option.ConnectionURL</name>
<value>[hostname]</value>
<description>JDBC connect string for a JDBC metastore</description>
</property>
<property>
<name>javax.jdo.option.ConnectionUserName</name>
<value>UserName</value>
<description>username to use against metastore database</description>
</property>
<property>
<name>javax.jdo.option.ConnectionPassword</name>
<value>PWD</value>
<description>password to use against metastore database</description>
</property>
3> connect to metastore, and below is the query to get partition information.
select D.NAME, P.PART_NAME, T.TBL_NAME from PARTITIONS P INNER JOIN TBLS T ON P.TBL_ID=T.TBL_ID INNER JOIN DBS D ON T.DB_ID=D.DB_ID WHERE D.NAME=<DBNAME> AND T.TBL_NAME=<TBLNAME> AND P.PART_NAME LIKE '%class=2%';
Once you have partition information, then you can make use of replace and concat function to derive alter statement.
Hope this helps.