ALTER INDEX

Function

ALTER INDEX modifies the definition of an existing index.

Precautions

• Only the owner of an index or a system administrator can run this statement.

Syntax

• Rename a table index.

  1 2	ALTER INDEX [ IF EXISTS ] index_name RENAME TO new_name;

• Modify the storage parameter of a table index.

  1 2	ALTER INDEX [ IF EXISTS ] index_name SET ( {storage_parameter = value} [, ... ] );

• Reset the storage parameter of a table index.

  1 2	ALTER INDEX [ IF EXISTS ] index_name RESET ( storage_parameter [, ... ] ) ;

• Set a table index or an index partition to be unavailable.

  1 2	ALTER INDEX [ IF EXISTS ] index_name [ MODIFY PARTITION index_partition_name ] UNUSABLE;

  

  The syntax cannot be used for column-store tables.

• Rebuild a table index or index partition.

  1 2	ALTER INDEX index_name REBUILD [ PARTITION index_partition_name ];

• Rename an index partition.

  1 2	ALTER INDEX [ IF EXISTS ] index_name RENAME PARTITION index_partition_name TO new_index_partition_name;

  

  PG_OBJECT does not support the record of the syntax when the last modification time of the index is recorded.

Parameter Description

• IF EXISTS

  If the specified index does not exist, a notice instead of an error is sent.

• RENAME TO

  Changes only the name of the index. There is no effect on the stored data.

• SET ( { STORAGE_PARAMETER = value } [, ...] )

  Change one or more index-method-specific storage parameters. Note that the index contents will not be modified immediately by this command. You might need to rebuild the index with REINDEX to get the desired effects depending on parameters.

• RESET ( { storage_parameter } [, ...] )

  Reset one or more index-method-specific storage parameters to the default value. Similar to the SET statement, REINDEX may be used to completely update the index.

• [ MODIFY PARTITION index_partition_name ] UNUSABLE

  Sets the index on a table or index partition to be unavailable.

• REBUILD [ PARTITION index_partition_name ]

  Recreates the index on a table or index partition.

• RENAME PARTITION

  Renames an index partition.

• COMMENT comment_text

  Adds, modifies, or deletes index comments.

• index_name

  Specifies the index name to be modified.

• new_name

  Specifies the new name for the index. The new index name cannot be the same as an existing table name in the database.

  Value range: a string that must comply with the identifier naming rules.

• storage_parameter

  Specifies the name of an index-method-specific parameter.

• value

  Specifies the new value for an index-method-specific storage parameter. This might be a number or a word depending on the parameter.

• new_index_partition_name

  Specifies the new name of the index partition.

• index_partition_name

  Specifies the name of the index partition.

• comment_text

  Comment of an index.

Example

• Modifying Table Index
  Create a sample table named tpcds.ship_mode_t1.

  1 2 3 4 5 6 7 8 9 10 11

  DROP TABLE IF EXISTS tpcds.ship_mode_t1; CREATE TABLE tpcds.ship_mode_t1 ( SM_SHIP_MODE_SK INTEGER NOT NULL, SM_SHIP_MODE_ID CHAR(16) NOT NULL, SM_TYPE CHAR(30) , SM_CODE CHAR(10) , SM_CARRIER CHAR(20) , SM_CONTRACT CHAR(20) ) DISTRIBUTE BY HASH(SM_SHIP_MODE_SK);

  Create a unique index on the SM_SHIP_MODE_SK column in the tpcds.ship_mode_t1 table.

  1 2	DROP INDEX IF EXISTS ds_ship_mode_t1_index1; CREATE UNIQUE INDEX ds_ship_mode_t1_index1 ON tpcds.ship_mode_t1(SM_SHIP_MODE_SK);

  Create an expression index on the SM_CODE column in the tpcds.ship_mode_t1 table.

  1 2	DROP INDEX IF EXISTS ds_ship_mode_t1_index2; CREATE INDEX ds_ship_mode_t1_index2 ON tpcds.ship_mode_t1(SUBSTR(SM_CODE,1 ,4));

  Rename the ds_ship_mode_t1_index1 index to ds_ship_mode_t1_index5:

  1	ALTER INDEX tpcds.ds_ship_mode_t1_index1 RENAME TO ds_ship_mode_t1_index5;

  Set the ds_ship_mode_t1_index2 index as unusable:

  1	ALTER INDEX tpcds.ds_ship_mode_t1_index2 UNUSABLE;

  Rebuild the ds_ship_mode_t1_index2 index:

  1	ALTER INDEX tpcds.ds_ship_mode_t1_index2 REBUILD;

• Modifying Partition Index
  Create a sample table named tpcds.customer_address_p1.

  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

  DROP TABLE IF EXISTS tpcds.customer_address_p1; CREATE TABLE tpcds.customer_address_p1 ( CA_ADDRESS_SK INTEGER NOT NULL, CA_ADDRESS_ID CHAR(16) NOT NULL, CA_STREET_NUMBER CHAR(10) , CA_STREET_NAME VARCHAR(60) , CA_STREET_TYPE CHAR(15) , CA_SUITE_NUMBER CHAR(10) , CA_CITY VARCHAR(60) , CA_COUNTY VARCHAR(30) , CA_STATE CHAR(2) , CA_ZIP CHAR(10) , CA_COUNTRY VARCHAR(20) , CA_GMT_OFFSET DECIMAL(5,2) , CA_LOCATION_TYPE CHAR(20) ) DISTRIBUTE BY HASH(CA_ADDRESS_SK) PARTITION BY RANGE(CA_ADDRESS_SK) ( PARTITION p1 VALUES LESS THAN (3000), PARTITION p2 VALUES LESS THAN (5000) , PARTITION p3 VALUES LESS THAN (MAXVALUE) ) ENABLE ROW MOVEMENT;

  Create the partitioned table index ds_customer_address_p1_index2 with the name of the index partition specified.

  1 2 3 4 5 6 7 8

  DROP INDEX IF EXISTS ds_customer_address_p1_index2; CREATE INDEX ds_customer_address_p1_index2 ON tpcds.customer_address_p1(CA_ADDRESS_SK) LOCAL ( PARTITION CA_ADDRESS_SK_index1, PARTITION CA_ADDRESS_SK_index2, PARTITION CA_ADDRESS_SK_index3 ) ;

  Rename the partition index tpcds. as ds_customer_address_p1_index2.

  1	ALTER INDEX tpcds.ds_customer_address_p1_index2 RENAME PARTITION CA_ADDRESS_SK_index1 TO CA_ADDRESS_SK_index4;

  Modify the index comment:

  1	ALTER INDEX tpcds.ds_customer_address_p1_index2 COMMENT 'comment_ds_customer_address_p1_index2';

Links

CREATE INDEX, DROP INDEX, REINDEX