ALTER INDEX(7) PostgreSQL 15.10 Documentation ALTER INDEX(7)
NAME
ALTER_INDEX - change the definition of an index
SYNOPSIS
ALTER INDEX [ IF EXISTS ] name RENAME TO new_name
ALTER INDEX [ IF EXISTS ] name SET TABLESPACE tablespace_name
ALTER INDEX name ATTACH PARTITION index_name
ALTER INDEX name [ NO ] DEPENDS ON EXTENSION extension_name
ALTER INDEX [ IF EXISTS ] name SET ( storage_parameter [= value] [, ... ] )
ALTER INDEX [ IF EXISTS ] name RESET ( storage_parameter [, ... ] )
ALTER INDEX [ IF EXISTS ] name ALTER [ COLUMN ] column_number
SET STATISTICS integer
ALTER INDEX ALL IN TABLESPACE name [ OWNED BY role_name [, ... ] ]
SET TABLESPACE new_tablespace [ NOWAIT ]
DESCRIPTION
ALTER INDEX changes the definition of an existing index. There are
several subforms described below. Note that the lock level required may
differ for each subform. An ACCESS EXCLUSIVE lock is held unless
explicitly noted. When multiple subcommands are listed, the lock held
will be the strictest one required from any subcommand.
RENAME
The RENAME form changes the name of the index. If the index is
associated with a table constraint (either UNIQUE, PRIMARY KEY, or
EXCLUDE), the constraint is renamed as well. There is no effect on
the stored data.
Renaming an index acquires a SHARE UPDATE EXCLUSIVE lock.
SET TABLESPACE
This form changes the index's tablespace to the specified
tablespace and moves the data file(s) associated with the index to
the new tablespace. To change the tablespace of an index, you must
own the index and have CREATE privilege on the new tablespace. All
indexes in the current database in a tablespace can be moved by
using the ALL IN TABLESPACE form, which will lock all indexes to be
moved and then move each one. This form also supports OWNED BY,
which will only move indexes owned by the roles specified. If the
NOWAIT option is specified then the command will fail if it is
unable to acquire all of the locks required immediately. Note that
system catalogs will not be moved by this command, use ALTER
DATABASE or explicit ALTER INDEX invocations instead if desired.
See also CREATE TABLESPACE.
ATTACH PARTITION index_name
Causes the named index (possibly schema-qualified) to become
attached to the altered index. The named index must be on a
partition of the table containing the index being altered, and have
an equivalent definition. An attached index cannot be dropped by
itself, and will automatically be dropped if its parent index is
dropped.
DEPENDS ON EXTENSION extension_name
NO DEPENDS ON EXTENSION extension_name
This form marks the index as dependent on the extension, or no
longer dependent on that extension if NO is specified. An index
that's marked as dependent on an extension is automatically dropped
when the extension is dropped.
SET ( storage_parameter [= value] [, ... ] )
This form changes one or more index-method-specific storage
parameters for the index. See CREATE INDEX for details on the
available parameters. Note that the index contents will not be
modified immediately by this command; depending on the parameter
you might need to rebuild the index with REINDEX to get the desired
effects.
RESET ( storage_parameter [, ... ] )
This form resets one or more index-method-specific storage
parameters to their defaults. As with SET, a REINDEX might be
needed to update the index entirely.
ALTER [ COLUMN ] column_number SET STATISTICS integer
This form sets the per-column statistics-gathering target for
subsequent ANALYZE operations, though can be used only on index
columns that are defined as an expression. Since expressions lack a
unique name, we refer to them using the ordinal number of the index
column. The target can be set in the range 0 to 10000;
alternatively, set it to -1 to revert to using the system default
statistics target (default_statistics_target). For more information
on the use of statistics by the PostgreSQL query planner, refer to
Section 14.2.
PARAMETERS
IF EXISTS
Do not throw an error if the index does not exist. A notice is
issued in this case.
column_number
The ordinal number refers to the ordinal (left-to-right) position
of the index column.
name
The name (possibly schema-qualified) of an existing index to alter.
new_name
The new name for the index.
tablespace_name
The tablespace to which the index will be moved.
extension_name
The name of the extension that the index is to depend on.
storage_parameter
The name of an index-method-specific storage parameter.
value
The new value for an index-method-specific storage parameter. This
might be a number or a word depending on the parameter.
NOTES
These operations are also possible using ALTER TABLE. ALTER INDEX is
in fact just an alias for the forms of ALTER TABLE that apply to
indexes.
There was formerly an ALTER INDEX OWNER variant, but this is now
ignored (with a warning). An index cannot have an owner different from
its table's owner. Changing the table's owner automatically changes the
index as well.
Changing any part of a system catalog index is not permitted.
EXAMPLES
To rename an existing index:
ALTER INDEX distributors RENAME TO suppliers;
To move an index to a different tablespace:
ALTER INDEX distributors SET TABLESPACE fasttablespace;
To change an index's fill factor (assuming that the index method
supports it):
ALTER INDEX distributors SET (fillfactor = 75);
REINDEX INDEX distributors;
Set the statistics-gathering target for an expression index:
CREATE INDEX coord_idx ON measured (x, y, (z + t));
ALTER INDEX coord_idx ALTER COLUMN 3 SET STATISTICS 1000;
COMPATIBILITY
ALTER INDEX is a PostgreSQL extension.
SEE ALSO
CREATE INDEX (CREATE_INDEX(7)), REINDEX(7)
PostgreSQL 15.10 2024 ALTER INDEX(7)
postgresql 15.10 - Generated Thu Dec 12 11:12:01 CST 2024