REINDEX

Function

REINDEX rebuilds an index using the data stored in the index's table, replacing the old copy of the index.

There are several scenarios in which REINDEX can be used:

• An index has become corrupted, and no longer contains valid data.
• An index has become "bloated", that is, it contains many empty or nearly-empty pages.
• You have altered a storage parameter (such as a fill factor) for an index, and wish that the change takes full effect.
• An index build with the CONCURRENTLY option failed, leaving an "invalid" index.

Precautions

REINDEX DATABASE and REINDEX SYSTEM type cannot be performed in transaction blocks.

Syntax

• Rebuild a general index.

  Reindex ::= REINDEX { INDEX [ CONCURRENTLY ] | [INTERNAL] TABLE | DATABASE | SYSTEM } name [ FORCE ];

• Rebuild an index partition.

  Reindex ::= REINDEX  { INDEX|  [INTERNAL] TABLE} name
      PARTITION partition_name [ FORCE  ];

Parameter Description

• INDEX

  Recreates the specified index.

• CONCURRENTLY

  Reindex index in a way that does not block DML statement execution.

• INTERNAL TABLE

  Recreates the Desc table index of a column-store table or Hadoop internal table. The TOAST table (if any) of the table is reindexed as well.

• TABLE

  Recreates all indexes of a specified table. If a table has a TOAST table, the table will also be reindexed. If an index in the table has been invalidated by running alter unusable, the index cannot be recreated.

• DATABASE

  Recreates all indexes within the current database.

• SYSTEM

  Recreates all indexes on system catalogs within the current database. Indexes on user tables are not processed.

• name

  Specifies the name of the index, table, or database whose index needs to be recreated. Tables and indexes can be schema-qualified.

  NOTE: REINDEX DATABASE and SYSTEM can create indexes for only the current database. Therefore, name must be the same as the current database name.

• FORCE

  Specifies an invalid option, which will be ignored.

• partition_name

  Specifies the name of the partition or index partition to be recreated.

  Value range:

  • If REINDEX INDEX is used, specify the name of an index partition.
  • If it is REINDEX TABLE, specify the name of a partition.
  • If it is REINDEX INTERNAL TABLE, specify the name of a partition in a column-store partitioned table.

NOTICE: REINDEX DATABASE and REINDEX SYSTEM type cannot be performed in transaction blocks.

Examples

-- Create a row-store table tpcds.customer_t1 and create an index on the c_customer_sk column in the table.
mogdb=# CREATE TABLE tpcds.customer_t1
(
    c_customer_sk             integer               not null,
    c_customer_id             char(16)              not null,
    c_current_cdemo_sk        integer                       ,
    c_current_hdemo_sk        integer                       ,
    c_current_addr_sk         integer                       ,
    c_first_shipto_date_sk    integer                       ,
    c_first_sales_date_sk     integer                       ,
    c_salutation              char(10)                      ,
    c_first_name              char(20)                      ,
    c_last_name               char(30)                      ,
    c_preferred_cust_flag     char(1)                       ,
    c_birth_day               integer                       ,
    c_birth_month             integer                       ,
    c_birth_year              integer                       ,
    c_birth_country           varchar(20)                   ,
    c_login                   char(13)                      ,
    c_email_address           char(50)                      ,
    c_last_review_date        char(10)
)
WITH (orientation = row);

mogdb=# CREATE INDEX tpcds_customer_index1 ON tpcds.customer_t1 (c_customer_sk);

mogdb=# INSERT INTO tpcds.customer_t1 SELECT * FROM tpcds.customer WHERE c_customer_sk < 10;

-- Rebuild a single index.
mogdb=# REINDEX INDEX tpcds.tpcds_customer_index1;

-- Rebuild all indexes in the tpcds.customer_t1 table:
mogdb=# REINDEX TABLE tpcds.customer_t1;

Delete the tpcds.customer_t1 table.
mogdb=# DROP TABLE tpcds.customer_t1;

Suggestions

• INTERNAL TABLE

  This scenario is used for fault recovery. You are not advised to perform concurrent operations.

• DATABASE

  You can not reindex a database in a transaction.

• SYSTEM

  You can not reindex system catalogs in transactions.