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

• Renames a table index. The new index name can be prefixed with the name of the schema where the original index is located, but the schema name cannot be changed at the same time.

  1 2 3 4

  ALTER INDEX [ IF EXISTS ] index_name RENAME TO new_name; ALTER INDEX [ IF EXISTS ] index_name RENAME TO schema.new_name;

• Modify the storage parameter of a table index.

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

• Modify the status flag of an index.

  1 2	ALTER INDEX [ IF EXISTS ] index_name SET ( {invisible = 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 ][WITHOUT UNUSABLE];

• 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.

• WITHOUT UNUSABLE

  Indexes that are in an UNUSABLE state are not rebuilt when rebuilding indexes in tables or index partitions. This parameter is supported only by clusters of version 8.3.0.100 or later.

• 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.

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

• storage_parameter

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

• invisible

  Controls whether the optimizer generates index scan plans.

  Value range:

  • ON indicates that no index scan plan is generated.
  • OFF indicates that an index scan plan is generated.

  Default value: OFF

• 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.

Examples

Rename the existing index ds_ship_mode_t1_index1 to tpcds. ds_ship_mode_t1_index5. The original schema name tpcds is prefixed to the new name.

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ALTER INDEX tpcds.ds_ship_mode_t1_index1 RENAME TO tpcds.ds_ship_mode_t1_index5;

Set the ds_ship_mode_t1_index2 index as unusable:

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ALTER INDEX tpcds.ds_ship_mode_t1_index2 UNUSABLE;

Rebuild the ds_ship_mode_t1_index2 index:

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ALTER INDEX tpcds.ds_ship_mode_t1_index2 REBUILD;

Rename a partitioned table index:

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ALTER INDEX tpcds.ds_customer_address_p1_index2 RENAME PARTITION CA_ADDRESS_SK_index1 TO CA_ADDRESS_SK_index4;

Modify the index comment:

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ALTER INDEX tpcds.ds_customer_address_p1_index2 COMMENT 'comment_ds_customer_address_p1_index2';

Links

CREATE INDEX, DROP INDEX, REINDEX