ALTER TABLE
Description
ALTER TABLE statement changes the schema or properties of a table.
RENAME
ALTER TABLE RENAME TO statement changes the table name of an existing table in the database. The table rename command cannot be used to move a table between databases, only to rename a table within the same database.
If the table is cached, the commands clear cached data of the table. The cache will be lazily filled when the next time the table is accessed. Additionally:
- the table rename command uncaches all table’s dependents such as views that refer to the table. The dependents should be cached again explicitly.
- the partition rename command clears caches of all table dependents while keeping them as cached. So, their caches will be lazily filled when the next time they are accessed.
Syntax
ALTER TABLE table_identifier RENAME TO table_identifier
ALTER TABLE table_identifier partition_spec RENAME TO partition_spec
Parameters
-
table_identifier
Specifies a table name, which may be optionally qualified with a database name.
Syntax:
[ database_name. ] table_name -
partition_spec
Partition to be renamed. Note that one can use a typed literal (e.g., date’2019-01-02’) in the partition spec.
Syntax:
PARTITION ( partition_col_name = partition_col_val [ , ... ] )
ADD COLUMNS
ALTER TABLE ADD COLUMNS statement adds mentioned columns to an existing table.
Syntax
ALTER TABLE table_identifier ADD COLUMNS ( col_spec [ , ... ] )
Parameters
-
table_identifier
Specifies a table name, which may be optionally qualified with a database name.
Syntax:
[ database_name. ] table_name -
COLUMNS ( col_spec )
Specifies the columns to be added.
ALTER OR CHANGE COLUMN
ALTER TABLE ALTER COLUMN or ALTER TABLE CHANGE COLUMN statement changes column’s definition.
Syntax
ALTER TABLE table_identifier { ALTER | CHANGE } [ COLUMN ] col_spec alterColumnAction
Parameters
-
table_identifier
Specifies a table name, which may be optionally qualified with a database name.
Syntax:
[ database_name. ] table_name -
COLUMNS ( col_spec )
Specifies the column to be altered or be changed.
-
alterColumnAction
Change column’s definition.
ADD AND DROP PARTITION
ADD PARTITION
ALTER TABLE ADD statement adds partition to the partitioned table.
If the table is cached, the command clears cached data of the table and all its dependents that refer to it. The cache will be lazily filled when the next time the table or the dependents are accessed.
Syntax
ALTER TABLE table_identifier ADD [IF NOT EXISTS]
( partition_spec [ partition_spec ... ] )
Parameters
-
table_identifier
Specifies a table name, which may be optionally qualified with a database name.
Syntax:
[ database_name. ] table_name -
partition_spec
Partition to be added. Note that one can use a typed literal (e.g., date’2019-01-02’) in the partition spec.
Syntax:
PARTITION ( partition_col_name = partition_col_val [ , ... ] )
DROP PARTITION
ALTER TABLE DROP statement drops the partition of the table.
If the table is cached, the command clears cached data of the table and all its dependents that refer to it. The cache will be lazily filled when the next time the table or the dependents are accessed.
Syntax
ALTER TABLE table_identifier DROP [ IF EXISTS ] partition_spec [PURGE]
Parameters
-
table_identifier
Specifies a table name, which may be optionally qualified with a database name.
Syntax:
[ database_name. ] table_name -
partition_spec
Partition to be dropped. Note that one can use a typed literal (e.g., date’2019-01-02’) in the partition spec.
Syntax:
PARTITION ( partition_col_name = partition_col_val [ , ... ] )
SET AND UNSET
SET TABLE PROPERTIES
ALTER TABLE SET command is used for setting the table properties. If a particular property was already set,
this overrides the old value with the new one.
ALTER TABLE UNSET is used to drop the table property.
Syntax
-- Set Table Properties
ALTER TABLE table_identifier SET TBLPROPERTIES ( key1 = val1, key2 = val2, ... )
-- Unset Table Properties
ALTER TABLE table_identifier UNSET TBLPROPERTIES [ IF EXISTS ] ( key1, key2, ... )
SET SERDE
ALTER TABLE SET command is used for setting the SERDE or SERDE properties in Hive tables. If a particular property was already set, this overrides the old value with the new one.
Syntax
-- Set SERDE Properties
ALTER TABLE table_identifier [ partition_spec ]
SET SERDEPROPERTIES ( key1 = val1, key2 = val2, ... )
ALTER TABLE table_identifier [ partition_spec ] SET SERDE serde_class_name
[ WITH SERDEPROPERTIES ( key1 = val1, key2 = val2, ... ) ]
SET LOCATION And SET FILE FORMAT
ALTER TABLE SET command can also be used for changing the file location and file format for
existing tables.
If the table is cached, the ALTER TABLE .. SET LOCATION command clears cached data of the table and all its dependents that refer to it. The cache will be lazily filled when the next time the table or the dependents are accessed.
Syntax
-- Changing File Format
ALTER TABLE table_identifier [ partition_spec ] SET FILEFORMAT file_format
-- Changing File Location
ALTER TABLE table_identifier [ partition_spec ] SET LOCATION 'new_location'
Parameters
-
table_identifier
Specifies a table name, which may be optionally qualified with a database name.
Syntax:
[ database_name. ] table_name -
partition_spec
Specifies the partition on which the property has to be set. Note that one can use a typed literal (e.g., date’2019-01-02’) in the partition spec.
Syntax:
PARTITION ( partition_col_name = partition_col_val [ , ... ] ) -
SERDEPROPERTIES ( key1 = val1, key2 = val2, … )
Specifies the SERDE properties to be set.
Examples
-- RENAME table
DESC student;
+-----------------------+---------+-------+
| col_name|data_type|comment|
+-----------------------+---------+-------+
| name| string| NULL|
| rollno| int| NULL|
| age| int| NULL|
|# Partition Information| | |
| # col_name|data_type|comment|
| age| int| NULL|
+-----------------------+---------+-------+
ALTER TABLE Student RENAME TO StudentInfo;
-- After Renaming the table
DESC StudentInfo;
+-----------------------+---------+-------+
| col_name|data_type|comment|
+-----------------------+---------+-------+
| name| string| NULL|
| rollno| int| NULL|
| age| int| NULL|
|# Partition Information| | |
| # col_name|data_type|comment|
| age| int| NULL|
+-----------------------+---------+-------+
-- RENAME partition
SHOW PARTITIONS StudentInfo;
+---------+
|partition|
+---------+
| age=10|
| age=11|
| age=12|
+---------+
ALTER TABLE default.StudentInfo PARTITION (age='10') RENAME TO PARTITION (age='15');
-- After renaming Partition
SHOW PARTITIONS StudentInfo;
+---------+
|partition|
+---------+
| age=11|
| age=12|
| age=15|
+---------+
-- Add new columns to a table
DESC StudentInfo;
+-----------------------+---------+-------+
| col_name|data_type|comment|
+-----------------------+---------+-------+
| name| string| NULL|
| rollno| int| NULL|
| age| int| NULL|
|# Partition Information| | |
| # col_name|data_type|comment|
| age| int| NULL|
+-----------------------+---------+-------+
ALTER TABLE StudentInfo ADD columns (LastName string, DOB timestamp);
-- After Adding New columns to the table
DESC StudentInfo;
+-----------------------+---------+-------+
| col_name|data_type|comment|
+-----------------------+---------+-------+
| name| string| NULL|
| rollno| int| NULL|
| LastName| string| NULL|
| DOB|timestamp| NULL|
| age| int| NULL|
|# Partition Information| | |
| # col_name|data_type|comment|
| age| int| NULL|
+-----------------------+---------+-------+
-- Add a new partition to a table
SHOW PARTITIONS StudentInfo;
+---------+
|partition|
+---------+
| age=11|
| age=12|
| age=15|
+---------+
ALTER TABLE StudentInfo ADD IF NOT EXISTS PARTITION (age=18);
-- After adding a new partition to the table
SHOW PARTITIONS StudentInfo;
+---------+
|partition|
+---------+
| age=11|
| age=12|
| age=15|
| age=18|
+---------+
-- Drop a partition from the table
SHOW PARTITIONS StudentInfo;
+---------+
|partition|
+---------+
| age=11|
| age=12|
| age=15|
| age=18|
+---------+
ALTER TABLE StudentInfo DROP IF EXISTS PARTITION (age=18);
-- After dropping the partition of the table
SHOW PARTITIONS StudentInfo;
+---------+
|partition|
+---------+
| age=11|
| age=12|
| age=15|
+---------+
-- Adding multiple partitions to the table
SHOW PARTITIONS StudentInfo;
+---------+
|partition|
+---------+
| age=11|
| age=12|
| age=15|
+---------+
ALTER TABLE StudentInfo ADD IF NOT EXISTS PARTITION (age=18) PARTITION (age=20);
-- After adding multiple partitions to the table
SHOW PARTITIONS StudentInfo;
+---------+
|partition|
+---------+
| age=11|
| age=12|
| age=15|
| age=18|
| age=20|
+---------+
-- ALTER OR CHANGE COLUMNS
DESC StudentInfo;
+-----------------------+---------+-------+
| col_name|data_type|comment|
+-----------------------+---------+-------+
| name| string| NULL|
| rollno| int| NULL|
| LastName| string| NULL|
| DOB|timestamp| NULL|
| age| int| NULL|
|# Partition Information| | |
| # col_name|data_type|comment|
| age| int| NULL|
+-----------------------+---------+-------+
ALTER TABLE StudentInfo ALTER COLUMN name COMMENT "new comment";
--After ALTER or CHANGE COLUMNS
DESC StudentInfo;
+-----------------------+---------+-----------+
| col_name|data_type| comment|
+-----------------------+---------+-----------+
| name| string|new comment|
| rollno| int| NULL|
| LastName| string| NULL|
| DOB|timestamp| NULL|
| age| int| NULL|
|# Partition Information| | |
| # col_name|data_type| comment|
| age| int| NULL|
+-----------------------+---------+-----------+
-- Change the fileformat
ALTER TABLE loc_orc SET fileformat orc;
ALTER TABLE p1 partition (month=2, day=2) SET fileformat parquet;
-- Change the file Location
ALTER TABLE dbx.tab1 PARTITION (a='1', b='2') SET LOCATION '/path/to/part/ways'
-- SET SERDE/ SERDE Properties
ALTER TABLE test_tab SET SERDE 'org.apache.hadoop.hive.serde2.columnar.LazyBinaryColumnarSerDe';
ALTER TABLE dbx.tab1 SET SERDE 'org.apache.hadoop' WITH SERDEPROPERTIES ('k' = 'v', 'kay' = 'vee')
-- SET TABLE PROPERTIES
ALTER TABLE dbx.tab1 SET TBLPROPERTIES ('winner' = 'loser');
-- SET TABLE COMMENT Using SET PROPERTIES
ALTER TABLE dbx.tab1 SET TBLPROPERTIES ('comment' = 'A table comment.');
-- Alter TABLE COMMENT Using SET PROPERTIES
ALTER TABLE dbx.tab1 SET TBLPROPERTIES ('comment' = 'This is a new comment.');
-- DROP TABLE PROPERTIES
ALTER TABLE dbx.tab1 UNSET TBLPROPERTIES ('winner');