REINDEX

Description

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. Currently, REINDEX operations cannot be performed on materialized views.

Syntax

Rebuild a general index.

REINDEX { INDEX | TABLE | DATABASE | SYSTEM } [CONCURRENTLY] name [ FORCE ];

Rebuild an index partition.

REINDEX  { INDEX|  TABLE} name
    PARTITION partition_name [ FORCE  ];

Parameters

INDEX
Rebuilds the specified index.
TABLE
Rebuilds 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 rebuilt. Indexes in the TOAST table cannot be rebuilt when specifying the CONCURRENTLY option.
DATABASE
Rebuilds all indexes within the current database. Indexes in the TOAST table within the current database cannot be rebuilt when specifying the CONCURRENTLY option.
SYSTEM
Rebuilds all indexes on system catalogs within the current database. Indexes on user tables are not processed.
CONCURRENTLY
Rebuilds an index (with ShareUpdateExclusiveLock) in non-blocking DML mode. When an index is rebuilt, other statements cannot access the table on which the index depends. If this keyword is specified, DML is not blocked during the rebuilding. Indexes in system catalogs cannot be rebuilt online. REINDEX INTERNAL TABLE CONCURRENTLY and REINDEX SYSTEM CONCURRENTLY are not supported. When REINDEX DATABASE CONCURRENTLY is executed, all indexes on user tables in the current database are rebuilt online (indexes on system catalogs are not processed). REINDEX CONCURRENTLY cannot be executed within a transaction. Only B-tree and UB-tree indexes can be created online and only common, global, and local indexes are supported. Online concurrent index rebuilding supports only Astore common indexes, global indexes, and local indexes. Ustore indexes are not supported. If online index rebuilding fails, invalid new indexes may be left. If the system cannot automatically clear the invalid indexes (for example, the database is shut down), you need to manually clear the invalid indexes (using the DROP INDEX statement) as soon as possible to prevent more resources from being occupied. Generally, the extension of an invalid index name is _ccnew. The execution of REINDEX INDEX CONCURRENTLY adds a four-level session lock to the table and its first several phases are similar to those of CREATE INDEX CONCURRENTLY. Therefore, the execution may be suspended or deadlocked, which is similar to that of CREATE INDEX CONCURRENTLY. For example, if two sessions perform the REINDEX CONCURRENTLY operation on the same index or table at the same time, a deadlock occurs. For details, see CONCURRENTLY.
name
Specifies the name of the index, table, or database whose index needs to be rebuilt. Tables and indexes can be schema-qualified.

REINDEX DATABASE and SYSTEM can rebuild indexes for only the current database. Therefore, name must be the same as the current database name.
FORCE
Discarded parameter. It is currently reserved for compatibility with earlier versions.
partition_name
Specifies the name of the partition or index partition to be rebuilt.

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.

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

Examples

-- Create a schema.
gaussdb=# CREATE SCHEMA tpcds;

-- Create the tpcds. customer table.
gaussdb=# CREATE TABLE tpcds.customer
(
c_customer_sk         INTEGER        NOT NULL,
c_customer_id         CHAR(16)       NOT NULL
);

-- Insert multiple records into the table.
gaussdb=# INSERT INTO tpcds.customer VALUES (1, 'AAAAAAAABAAAAAAA'),(5, 'AAAAAAAACAAAAAAA'),(10, 'AAAAAAAADAAAAAAA');

-- Create a row-store table tpcds.customer_t1 and create an index on the c_customer_sk column in the table.
gaussdb=# 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);

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

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

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

-- Rebuild a single index online.
gaussdb=# REINDEX INDEX CONCURRENTLY tpcds.tpcds_customer_index1;

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

-- Rebuild all indexes in the tpcds.customer_t1 table online.
gaussdb=# REINDEX TABLE CONCURRENTLY tpcds.customer_t1;

-- Delete the tpcds.customer_t1 table.
gaussdb=# DROP TABLE tpcds.customer_t1;

-- Drop the table.
gaussdb=# DROP TABLE tpcds.customer;

-- Delete a schema.
gaussdb=# DROP SCHEMA tpcds CASCADE;