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REINDEX()
NAME
  REINDEX - rebuild indexes

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

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
  to use REINDEX:

  · An index has become corrupted, and no longer contains valid data.
    Although in theory this should never happen, in practice indexes may
    become corrupted due to software bugs or hardware failures. REINDEX
    provides a recovery method.

  · An index has become ``bloated'', that it is contains many empty or
    nearly-empty pages. This can occur with B-tree indexes in PostgreSQL
    under certain uncommon access patterns. REINDEX provides a way to reduce
    the space consumption of the index by writing a new version of the index
    without the dead pages. See in the documentation for more information.

  · You have altered a storage parameter (such as fillfactor) for an index,
    and wish to ensure that the change has taken full effect.

  · An index build with the CONCURRENTLY option failed, leaving an
    ``invalid'' index. Such indexes are useless but it can be convenient to
    use REINDEX to rebuild them. Note that REINDEX will not perform a
    concurrent build. To build the index without interfering with production
    you should drop the index and reissue the CREATE INDEX CONCURRENTLY
    command.

PARAMETERS
  INDEX
       Recreate the specified index.

  TABLE
       Recreate all indexes of the specified table. If the table has a
       secondary ``TOAST'' table, that is reindexed as well.

  DATABASE
       Recreate all indexes within the current database.  Indexes on shared
       system catalogs are skipped except in stand-alone mode (see below).
       This form of REINDEX cannot be executed inside a transaction block.

  SYSTEM
       Recreate all indexes on system catalogs within the current database.
       Indexes on user tables are not processed. Also, indexes on shared
       system catalogs are skipped except in stand-alone mode (see below).
       This form of REINDEX cannot be executed inside a transaction block.

  name The name of the specific index, table, or database to be reindexed.
       Index and table names may be schema-qualified.  Presently, REINDEX
       DATABASE and REINDEX SYSTEM can only reindex the current database, so
       their parameter must match the current database's name.

  FORCE
       This is an obsolete option; it is ignored if specified.

NOTES
  If you suspect corruption of an index on a user table, you can simply
  rebuild that index, or all indexes on the table, using REINDEX INDEX or
  REINDEX TABLE.

  Things are more difficult if you need to recover from corruption of an
  index on a system table. In this case it's important for the system to not
  have used any of the suspect indexes itself.	(Indeed, in this sort of
  scenario you may find that server processes are crashing immediately at
  start-up, due to reliance on the corrupted indexes.) To recover safely, the
  server must be started with the -P option, which prevents it from using
  indexes for system catalog lookups.

  One way to do this is to shut down the server and start a single-user
  PostgreSQL server with the -P option included on its command line.  Then,
  REINDEX DATABASE, REINDEX SYSTEM, REINDEX TABLE, or REINDEX INDEX can be
  issued, depending on how much you want to reconstruct. If in doubt, use
  REINDEX SYSTEM to select reconstruction of all system indexes in the
  database. Then quit the single-user server session and restart the regular
  server.  See the postgres(1) reference page for more information about how
  to interact with the single-user server interface.

  Alternatively, a regular server session can be started with -P included in
  its command line options.  The method for doing this varies across clients,
  but in all libpq-based clients, it is possible to set the PGOPTIONS
  environment variable to -P before starting the client. Note that while this
  method does not require locking out other clients, it may still be wise to
  prevent other users from connecting to the damaged database until repairs
  have been completed.

  If corruption is suspected in the indexes of any of the shared system
  catalogs (which are pg_authid, pg_auth_members, pg_database, pg_pltemplate,
  pg_shdepend, pg_shdescription, and pg_tablespace), then a standalone server
  must be used to repair it. REINDEX will not process shared catalogs in
  multiuser mode.

  For all indexes except the shared system catalogs, REINDEX is crash-safe
  and transaction-safe. REINDEX is not crash-safe for shared indexes, which
  is why this case is disallowed during normal operation. If a failure occurs
  while reindexing one of these catalogs in standalone mode, it will not be
  possible to restart the regular server until the problem is rectified. (The
  typical symptom of a partially rebuilt shared index is ``index is not a
  btree'' errors.)

  REINDEX is similar to a drop and recreate of the index in that the index
  contents are rebuilt from scratch. However, the locking considerations are
  rather different. REINDEX locks out writes but not reads of the index's
  parent table. It also takes an exclusive lock on the specific index being
  processed, which will block reads that attempt to use that index. In
  contrast, DROP INDEX momentarily takes exclusive lock on the parent table,
  blocking both writes and reads. The subsequent CREATE INDEX locks out
  writes but not reads; since the index is not there, no read will attempt to
  use it, meaning that there will be no blocking but reads may be forced into
  expensive sequential scans. Another important point is that the drop/create
  approach invalidates any cached query plans that use the index, while
  REINDEX does not.

  Reindexing a single index or table requires being the owner of that index
  or table. Reindexing a database requires being the owner of the database
  (note that the owner can therefore rebuild indexes of tables owned by other
  users). Of course, superusers can always reindex anything.

  Prior to PostgreSQL 8.1, REINDEX DATABASE processed only system indexes,
  not all indexes as one would expect from the name. This has been changed to
  reduce the surprise factor. The old behavior is available as REINDEX
  SYSTEM.

  Prior to PostgreSQL 7.4, REINDEX TABLE did not automatically process TOAST
  tables, and so those had to be reindexed by separate commands. This is
  still possible, but redundant.

EXAMPLES
  Rebuild a single index:

  REINDEX INDEX my_index;

  Rebuild all the indexes on the table my_table:

  REINDEX TABLE my_table;

  Rebuild all indexes in a particular database, without trusting the system
  indexes to be valid already:

  $ export PGOPTIONS="-P"
  $ psql broken_db
  broken_db=> REINDEX DATABASE broken_db;
  broken_db=> \q

COMPATIBILITY
  There is no REINDEX command in the SQL standard.

Index for Section 5

Alphabetical listing for R

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