ALTER TABLE

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.

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.

    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.

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.

    Syntax: PARTITION ( partition_col_name  = partition_col_val [ , ... ] )

DROP PARTITION

ALTER TABLE DROP statement drops the partition of the table.

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.

    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.

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.

    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');

Delta Lake schema constructs

Delta Lake supports additional constructs for modifying table schema: add, change, and replace columns.

For add, change, and replace column examples, see Explicitly update schema.

Add columns 

ALTER TABLE table_name ADD COLUMNS (col_name data_type [COMMENT col_comment] [FIRST|AFTER colA_name], ...)

ALTER TABLE table_name ADD COLUMNS (col_name.nested_col_name data_type [COMMENT col_comment] [FIRST|AFTER colA_name], ...)

Add columns to an existing table. It supports adding nested column. If a column with the same name already exists in the table or the same nested struct, an exception is thrown.

Change columns 

ALTER TABLE table_name (ALTER|CHANGE) [COLUMN] alterColumnAction

ALTER TABLE table_name (ALTER|CHANGE) [COLUMN] alterColumnAction

alterColumnAction:
    : TYPE dataType
    : [COMMENT col_comment]
    : [FIRST|AFTER colA_name]
    : (SET | DROP) NOT NULL

Change a column definition of an existing table. You can change the data type, comment, nullability of a column or reorder columns.

Note

Available in Databricks Runtime 7.0 and above.

Change columns (Hive syntax) 

ALTER TABLE table_name CHANGE [COLUMN] col_name col_name data_type [COMMENT col_comment] [FIRST|AFTER colA_name]

ALTER TABLE table_name CHANGE [COLUMN] col_name.nested_col_name col_name data_type [COMMENT col_comment] [FIRST|AFTER colA_name]

Change a column definition of an existing table. You can change the comment of the column and reorder columns.

Note

In Databricks Runtime 7.0 and above you cannot use CHANGE COLUMN:

  • To change the contents of complex data types such as structs. Instead use ADD COLUMNS to add new columns to nested fields, or ALTER COLUMN to change the properties of a nested column.
  • To relax the nullability of a column in a Delta table. Instead use ALTER TABLE table_name ALTER COLUMN column_name DROP NOT NULL.

Replace columns 

ALTER TABLE table_name REPLACE COLUMNS (col_name1 col_type1 [COMMENT col_comment1], ...)

Replace the column definitions of an existing table. It supports changing the comments of columns, adding columns, and reordering columns. If specified column definitions are not compatible with the existing definitions, an exception is thrown.