ALTER_TABLE man page on Oracle

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ALTER TABLE(7)		PostgreSQL 9.2.7 Documentation		ALTER TABLE(7)

       ALTER_TABLE - change the definition of a table

       ALTER TABLE [ IF EXISTS ] [ ONLY ] name [ * ]
	   action [, ... ]
       ALTER TABLE [ IF EXISTS ] [ ONLY ] name [ * ]
	   RENAME [ COLUMN ] column_name TO new_column_name
       ALTER TABLE [ IF EXISTS ] [ ONLY ] name [ * ]
	   RENAME CONSTRAINT constraint_name TO new_constraint_name
       ALTER TABLE [ IF EXISTS ] name
	   RENAME TO new_name
       ALTER TABLE [ IF EXISTS ] name
	   SET SCHEMA new_schema

       where action is one of:

	   ADD [ COLUMN ] column_name data_type [ COLLATE collation ] [ column_constraint [ ... ] ]
	   DROP [ COLUMN ] [ IF EXISTS ] column_name [ RESTRICT | CASCADE ]
	   ALTER [ COLUMN ] column_name [ SET DATA ] TYPE data_type [ COLLATE collation ] [ USING expression ]
	   ALTER [ COLUMN ] column_name SET DEFAULT expression
	   ALTER [ COLUMN ] column_name DROP DEFAULT
	   ALTER [ COLUMN ] column_name { SET | DROP } NOT NULL
	   ALTER [ COLUMN ] column_name SET STATISTICS integer
	   ALTER [ COLUMN ] column_name SET ( attribute_option = value [, ... ] )
	   ALTER [ COLUMN ] column_name RESET ( attribute_option [, ... ] )
	   ADD table_constraint [ NOT VALID ]
	   ADD table_constraint_using_index
	   VALIDATE CONSTRAINT constraint_name
	   DISABLE TRIGGER [ trigger_name | ALL | USER ]
	   ENABLE TRIGGER [ trigger_name | ALL | USER ]
	   ENABLE ALWAYS TRIGGER trigger_name
	   DISABLE RULE rewrite_rule_name
	   ENABLE RULE rewrite_rule_name
	   ENABLE REPLICA RULE rewrite_rule_name
	   ENABLE ALWAYS RULE rewrite_rule_name
	   CLUSTER ON index_name
	   SET ( storage_parameter = value [, ... ] )
	   RESET ( storage_parameter [, ... ] )
	   INHERIT parent_table
	   NO INHERIT parent_table
	   OF type_name
	   NOT OF
	   OWNER TO new_owner
	   SET TABLESPACE new_tablespace

       and table_constraint_using_index is:

	   [ CONSTRAINT constraint_name ]

       ALTER TABLE changes the definition of an existing table. There are
       several subforms:

	   This form adds a new column to the table, using the same syntax as

	   This form drops a column from a table. Indexes and table
	   constraints involving the column will be automatically dropped as
	   well. You will need to say CASCADE if anything outside the table
	   depends on the column, for example, foreign key references or
	   views. If IF EXISTS is specified and the column does not exist, no
	   error is thrown. In this case a notice is issued instead.

       IF EXISTS
	   Do not throw an error if the table does not exist. A notice is
	   issued in this case.

	   This form changes the type of a column of a table. Indexes and
	   simple table constraints involving the column will be automatically
	   converted to use the new column type by reparsing the originally
	   supplied expression. The optional COLLATE clause specifies a
	   collation for the new column; if omitted, the collation is the
	   default for the new column type. The optional USING clause
	   specifies how to compute the new column value from the old; if
	   omitted, the default conversion is the same as an assignment cast
	   from old data type to new. A USING clause must be provided if there
	   is no implicit or assignment cast from old to new type.

	   These forms set or remove the default value for a column. The
	   default values only apply to subsequent INSERT commands; they do
	   not cause rows already in the table to change. Defaults can also be
	   created for views, in which case they are inserted into INSERT
	   statements on the view before the view's ON INSERT rule is applied.

	   These forms change whether a column is marked to allow null values
	   or to reject null values. You can only use SET NOT NULL when the
	   column contains no null values.

	   This form sets the per-column statistics-gathering target for
	   subsequent ANALYZE(7) operations. 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, “Statistics Used by the
	   Planner”, in the documentation.

       SET ( attribute_option = value [, ... ] ), RESET ( attribute_option [,
       ... ] )
	   This form sets or resets per-attribute options. Currently, the only
	   defined per-attribute options are n_distinct and
	   n_distinct_inherited, which override the number-of-distinct-values
	   estimates made by subsequent ANALYZE(7) operations.	n_distinct
	   affects the statistics for the table itself, while
	   n_distinct_inherited affects the statistics gathered for the table
	   plus its inheritance children. When set to a positive value,
	   ANALYZE will assume that the column contains exactly the specified
	   number of distinct nonnull values. When set to a negative value,
	   which must be greater than or equal to -1, ANALYZE will assume that
	   the number of distinct nonnull values in the column is linear in
	   the size of the table; the exact count is to be computed by
	   multiplying the estimated table size by the absolute value of the
	   given number. For example, a value of -1 implies that all values in
	   the column are distinct, while a value of -0.5 implies that each
	   value appears twice on the average. This can be useful when the
	   size of the table changes over time, since the multiplication by
	   the number of rows in the table is not performed until query
	   planning time. Specify a value of 0 to revert to estimating the
	   number of distinct values normally. For more information on the use
	   of statistics by the PostgreSQL query planner, refer to Section
	   14.2, “Statistics Used by the Planner”, in the documentation.

	   This form sets the storage mode for a column. This controls whether
	   this column is held inline or in a secondary TOAST table, and
	   whether the data should be compressed or not.  PLAIN must be used
	   for fixed-length values such as integer and is inline,
	   uncompressed.  MAIN is for inline, compressible data.  EXTERNAL is
	   for external, uncompressed data, and EXTENDED is for external,
	   compressed data.  EXTENDED is the default for most data types that
	   support non-PLAIN storage. Use of EXTERNAL will make substring
	   operations on very large text and bytea values run faster, at the
	   penalty of increased storage space. Note that SET STORAGE doesn't
	   itself change anything in the table, it just sets the strategy to
	   be pursued during future table updates. See Section 56.2, “TOAST”,
	   in the documentation for more information.

       ADD table_constraint [ NOT VALID ]
	   This form adds a new constraint to a table using the same syntax as
	   CREATE TABLE (CREATE_TABLE(7)), plus the option NOT VALID, which is
	   currently only allowed for foreign key and CHECK constraints. If
	   the constraint is marked NOT VALID, the potentially-lengthy initial
	   check to verify that all rows in the table satisfy the constraint
	   is skipped. The constraint will still be enforced against
	   subsequent inserts or updates (that is, they'll fail unless there
	   is a matching row in the referenced table, in the case of foreign
	   keys; and they'll fail unless the new row matches the specified
	   check constraints). But the database will not assume that the
	   constraint holds for all rows in the table, until it is validated
	   by using the VALIDATE CONSTRAINT option.

       ADD table_constraint_using_index
	   This form adds a new PRIMARY KEY or UNIQUE constraint to a table
	   based on an existing unique index. All the columns of the index
	   will be included in the constraint.

	   The index cannot have expression columns nor be a partial index.
	   Also, it must be a b-tree index with default sort ordering. These
	   restrictions ensure that the index is equivalent to one that would
	   be built by a regular ADD PRIMARY KEY or ADD UNIQUE command.

	   If PRIMARY KEY is specified, and the index's columns are not
	   already marked NOT NULL, then this command will attempt to do ALTER
	   COLUMN SET NOT NULL against each such column. That requires a full
	   table scan to verify the column(s) contain no nulls. In all other
	   cases, this is a fast operation.

	   If a constraint name is provided then the index will be renamed to
	   match the constraint name. Otherwise the constraint will be named
	   the same as the index.

	   After this command is executed, the index is “owned” by the
	   constraint, in the same way as if the index had been built by a
	   regular ADD PRIMARY KEY or ADD UNIQUE command. In particular,
	   dropping the constraint will make the index disappear too.

	       Adding a constraint using an existing index can be helpful in
	       situations where a new constraint needs to be added without
	       blocking table updates for a long time. To do that, create the
	       index using CREATE INDEX CONCURRENTLY, and then install it as
	       an official constraint using this syntax. See the example

	   This form validates a foreign key or check constraint that was
	   previously created as NOT VALID, by scanning the table to ensure
	   there are no rows for which the constraint is not satisfied.
	   Nothing happens if the constraint is already marked valid.

	   Validation can be a long process on larger tables and currently
	   requires an ACCESS EXCLUSIVE lock. The value of separating
	   validation from initial creation is that you can defer validation
	   to less busy times, or can be used to give additional time to
	   correct pre-existing errors while preventing new errors.

	   This form drops the specified constraint on a table. If IF EXISTS
	   is specified and the constraint does not exist, no error is thrown.
	   In this case a notice is issued instead.

	   These forms configure the firing of trigger(s) belonging to the
	   table. A disabled trigger is still known to the system, but is not
	   executed when its triggering event occurs. For a deferred trigger,
	   the enable status is checked when the event occurs, not when the
	   trigger function is actually executed. One can disable or enable a
	   single trigger specified by name, or all triggers on the table, or
	   only user triggers (this option excludes internally generated
	   constraint triggers such as those that are used to implement
	   foreign key constraints or deferrable uniqueness and exclusion
	   constraints). Disabling or enabling internally generated constraint
	   triggers requires superuser privileges; it should be done with
	   caution since of course the integrity of the constraint cannot be
	   guaranteed if the triggers are not executed. The trigger firing
	   mechanism is also affected by the configuration variable
	   session_replication_role. Simply enabled triggers will fire when
	   the replication role is “origin” (the default) or “local”. Triggers
	   configured as ENABLE REPLICA will only fire if the session is in
	   “replica” mode, and triggers configured as ENABLE ALWAYS will fire
	   regardless of the current replication mode.

	   These forms configure the firing of rewrite rules belonging to the
	   table. A disabled rule is still known to the system, but is not
	   applied during query rewriting. The semantics are as for
	   disabled/enabled triggers. This configuration is ignored for ON
	   SELECT rules, which are always applied in order to keep views
	   working even if the current session is in a non-default replication

	   This form selects the default index for future CLUSTER(7)
	   operations. It does not actually re-cluster the table.

	   This form removes the most recently used CLUSTER(7) index
	   specification from the table. This affects future cluster
	   operations that don't specify an index.

	   This form adds an oid system column to the table (see Section 5.4,
	   “System Columns”, in the documentation). It does nothing if the
	   table already has OIDs.

	   Note that this is not equivalent to ADD COLUMN oid oid; that would
	   add a normal column that happened to be named oid, not a system

	   This form removes the oid system column from the table. This is
	   exactly equivalent to DROP COLUMN oid RESTRICT, except that it will
	   not complain if there is already no oid column.

       SET ( storage_parameter = value [, ... ] )
	   This form changes one or more storage parameters for the table. See
	   Storage Parameters for details on the available parameters. Note
	   that the table contents will not be modified immediately by this
	   command; depending on the parameter you might need to rewrite the
	   table to get the desired effects. That can be done with VACUUM
	   FULL, CLUSTER(7) or one of the forms of ALTER TABLE that forces a
	   table rewrite.

	       While CREATE TABLE allows OIDS to be specified in the WITH
	       (storage_parameter) syntax, ALTER TABLE does not treat OIDS as
	       a storage parameter. Instead use the SET WITH OIDS and SET
	       WITHOUT OIDS forms to change OID status.

       RESET ( storage_parameter [, ... ] )
	   This form resets one or more storage parameters to their defaults.
	   As with SET, a table rewrite might be needed to update the table

       INHERIT parent_table
	   This form adds the target table as a new child of the specified
	   parent table. Subsequently, queries against the parent will include
	   records of the target table. To be added as a child, the target
	   table must already contain all the same columns as the parent (it
	   could have additional columns, too). The columns must have matching
	   data types, and if they have NOT NULL constraints in the parent
	   then they must also have NOT NULL constraints in the child.

	   There must also be matching child-table constraints for all CHECK
	   constraints of the parent, except those marked non-inheritable
	   (that is, created with ALTER TABLE ... ADD CONSTRAINT ... NO
	   INHERIT) in the parent, which are ignored; all child-table
	   constraints matched must not be marked non-inheritable. Currently
	   UNIQUE, PRIMARY KEY, and FOREIGN KEY constraints are not
	   considered, but this might change in the future.

       NO INHERIT parent_table
	   This form removes the target table from the list of children of the
	   specified parent table. Queries against the parent table will no
	   longer include records drawn from the target table.

       OF type_name
	   This form links the table to a composite type as though CREATE
	   TABLE OF had formed it. The table's list of column names and types
	   must precisely match that of the composite type; the presence of an
	   oid system column is permitted to differ. The table must not
	   inherit from any other table. These restrictions ensure that CREATE
	   TABLE OF would permit an equivalent table definition.

       NOT OF
	   This form dissociates a typed table from its type.

	   This form changes the owner of the table, sequence, or view to the
	   specified user.

	   This form changes the table's tablespace to the specified
	   tablespace and moves the data file(s) associated with the table to
	   the new tablespace. Indexes on the table, if any, are not moved;
	   but they can be moved separately with additional SET TABLESPACE

	   The RENAME forms change the name of a table (or an index, sequence,
	   or view), the name of an individual column in a table, or the name
	   of a constraint of the table. There is no effect on the stored

	   This form moves the table into another schema. Associated indexes,
	   constraints, and sequences owned by table columns are moved as

       All the actions except RENAME and SET SCHEMA can be combined into a
       list of multiple alterations to apply in parallel. For example, it is
       possible to add several columns and/or alter the type of several
       columns in a single command. This is particularly useful with large
       tables, since only one pass over the table need be made.

       You must own the table to use ALTER TABLE. To change the schema of a
       table, you must also have CREATE privilege on the new schema. To add
       the table as a new child of a parent table, you must own the parent
       table as well. To alter the owner, you must also be a direct or
       indirect member of the new owning role, and that role must have CREATE
       privilege on the table's schema. (These restrictions enforce that
       altering the owner doesn't do anything you couldn't do by dropping and
       recreating the table. However, a superuser can alter ownership of any
       table anyway.) To add a column or alter a column type or use the OF
       clause, you must also have USAGE privilege on the data type.

	   The name (optionally schema-qualified) of an existing table to
	   alter. If ONLY is specified before the table name, only that table
	   is altered. If ONLY is not specified, the table and all its
	   descendant tables (if any) are altered. Optionally, * can be
	   specified after the table name to explicitly indicate that
	   descendant tables are included.

	   Name of a new or existing column.

	   New name for an existing column.

	   New name for the table.

	   Data type of the new column, or new data type for an existing

	   New table constraint for the table.

	   Name of an existing constraint to drop.

	   Automatically drop objects that depend on the dropped column or
	   constraint (for example, views referencing the column).

	   Refuse to drop the column or constraint if there are any dependent
	   objects. This is the default behavior.

	   Name of a single trigger to disable or enable.

	   Disable or enable all triggers belonging to the table. (This
	   requires superuser privilege if any of the triggers are internally
	   generated constraint triggers such as those that are used to
	   implement foreign key constraints or deferrable uniqueness and
	   exclusion constraints.)

	   Disable or enable all triggers belonging to the table except for
	   internally generated constraint triggers such as those that are
	   used to implement foreign key constraints or deferrable uniqueness
	   and exclusion constraints.

	   The index name on which the table should be marked for clustering.

	   The name of a table storage parameter.

	   The new value for a table storage parameter. This might be a number
	   or a word depending on the parameter.

	   A parent table to associate or de-associate with this table.

	   The user name of the new owner of the table.

	   The name of the tablespace to which the table will be moved.

	   The name of the schema to which the table will be moved.

       The key word COLUMN is noise and can be omitted.

       When a column is added with ADD COLUMN, all existing rows in the table
       are initialized with the column's default value (NULL if no DEFAULT
       clause is specified).

       Adding a column with a non-null default or changing the type of an
       existing column will require the entire table and indexes to be
       rewritten. As an exception, if the USING clause does not change the
       column contents and the old type is either binary coercible to the new
       type or an unconstrained domain over the new type, a table rewrite is
       not needed, but any indexes on the affected columns must still be
       rebuilt. Adding or removing a system oid column also requires rewriting
       the entire table. Table and/or index rebuilds may take a significant
       amount of time for a large table; and will temporarily require as much
       as double the disk space.

       Adding a CHECK or NOT NULL constraint requires scanning the table to
       verify that existing rows meet the constraint.

       The main reason for providing the option to specify multiple changes in
       a single ALTER TABLE is that multiple table scans or rewrites can
       thereby be combined into a single pass over the table.

       The DROP COLUMN form does not physically remove the column, but simply
       makes it invisible to SQL operations. Subsequent insert and update
       operations in the table will store a null value for the column. Thus,
       dropping a column is quick but it will not immediately reduce the
       on-disk size of your table, as the space occupied by the dropped column
       is not reclaimed. The space will be reclaimed over time as existing
       rows are updated. (These statements do not apply when dropping the
       system oid column; that is done with an immediate rewrite.)

       To force an immediate rewrite of the table, you can use VACUUM FULL,
       CLUSTER(7) or one of the forms of ALTER TABLE that forces a rewrite.
       This results in no semantically-visible change in the table, but gets
       rid of no-longer-useful data.

       The USING option of SET DATA TYPE can actually specify any expression
       involving the old values of the row; that is, it can refer to other
       columns as well as the one being converted. This allows very general
       conversions to be done with the SET DATA TYPE syntax. Because of this
       flexibility, the USING expression is not applied to the column's
       default value (if any); the result might not be a constant expression
       as required for a default. This means that when there is no implicit or
       assignment cast from old to new type, SET DATA TYPE might fail to
       convert the default even though a USING clause is supplied. In such
       cases, drop the default with DROP DEFAULT, perform the ALTER TYPE, and
       then use SET DEFAULT to add a suitable new default. Similar
       considerations apply to indexes and constraints involving the column.

       If a table has any descendant tables, it is not permitted to add,
       rename, or change the type of a column, or rename an inherited
       constraint in the parent table without doing the same to the
       descendants. That is, ALTER TABLE ONLY will be rejected. This ensures
       that the descendants always have columns matching the parent.

       A recursive DROP COLUMN operation will remove a descendant table's
       column only if the descendant does not inherit that column from any
       other parents and never had an independent definition of the column. A
       nonrecursive DROP COLUMN (i.e., ALTER TABLE ONLY ... DROP COLUMN) never
       removes any descendant columns, but instead marks them as independently
       defined rather than inherited.

       The TRIGGER, CLUSTER, OWNER, and TABLESPACE actions never recurse to
       descendant tables; that is, they always act as though ONLY were
       specified. Adding a constraint recurses only for CHECK constraints that
       are not marked NO INHERIT.

       Changing any part of a system catalog table is not permitted.

       Refer to CREATE TABLE (CREATE_TABLE(7)) for a further description of
       valid parameters.  Chapter 5, Data Definition, in the documentation has
       further information on inheritance.

       To add a column of type varchar to a table:

	   ALTER TABLE distributors ADD COLUMN address varchar(30);

       To drop a column from a table:

	   ALTER TABLE distributors DROP COLUMN address RESTRICT;

       To change the types of two existing columns in one operation:

	   ALTER TABLE distributors
	       ALTER COLUMN address TYPE varchar(80),
	       ALTER COLUMN name TYPE varchar(100);

       To change an integer column containing UNIX timestamps to timestamp
       with time zone via a USING clause:

	       ALTER COLUMN foo_timestamp SET DATA TYPE timestamp with time zone
		   timestamp with time zone 'epoch' + foo_timestamp * interval '1 second';

       The same, when the column has a default expression that won't
       automatically cast to the new data type:

	       ALTER COLUMN foo_timestamp DROP DEFAULT,
	       ALTER COLUMN foo_timestamp TYPE timestamp with time zone
		   timestamp with time zone 'epoch' + foo_timestamp * interval '1 second',
	       ALTER COLUMN foo_timestamp SET DEFAULT now();

       To rename an existing column:

	   ALTER TABLE distributors RENAME COLUMN address TO city;

       To rename an existing table:

	   ALTER TABLE distributors RENAME TO suppliers;

       To rename an existing constraint:

	   ALTER TABLE distributors RENAME CONSTRAINT zipchk TO zip_check;

       To add a not-null constraint to a column:

	   ALTER TABLE distributors ALTER COLUMN street SET NOT NULL;

       To remove a not-null constraint from a column:


       To add a check constraint to a table and all its children:

	   ALTER TABLE distributors ADD CONSTRAINT zipchk CHECK (char_length(zipcode) = 5);

       To add a check constraint only to a table and not to its children:

	   ALTER TABLE distributors ADD CONSTRAINT zipchk CHECK (char_length(zipcode) = 5) NO INHERIT;

       (The check constraint will not be inherited by future children,

       To remove a check constraint from a table and all its children:

	   ALTER TABLE distributors DROP CONSTRAINT zipchk;

       To remove a check constraint from one table only:

	   ALTER TABLE ONLY distributors DROP CONSTRAINT zipchk;

       (The check constraint remains in place for any child tables.)

       To add a foreign key constraint to a table:

	   ALTER TABLE distributors ADD CONSTRAINT distfk FOREIGN KEY (address) REFERENCES addresses (address);

       To add a (multicolumn) unique constraint to a table:

	   ALTER TABLE distributors ADD CONSTRAINT dist_id_zipcode_key UNIQUE (dist_id, zipcode);

       To add an automatically named primary key constraint to a table, noting
       that a table can only ever have one primary key:

	   ALTER TABLE distributors ADD PRIMARY KEY (dist_id);

       To move a table to a different tablespace:

	   ALTER TABLE distributors SET TABLESPACE fasttablespace;

       To move a table to a different schema:

	   ALTER TABLE myschema.distributors SET SCHEMA yourschema;

       To recreate a primary key constraint, without blocking updates while
       the index is rebuilt:

	   CREATE UNIQUE INDEX CONCURRENTLY dist_id_temp_idx ON distributors (dist_id);
	   ALTER TABLE distributors DROP CONSTRAINT distributors_pkey,
	       ADD CONSTRAINT distributors_pkey PRIMARY KEY USING INDEX dist_id_temp_idx;

       The forms ADD (without USING INDEX), DROP, SET DEFAULT, and SET DATA
       TYPE (without USING) conform with the SQL standard. The other forms are
       PostgreSQL extensions of the SQL standard. Also, the ability to specify
       more than one manipulation in a single ALTER TABLE command is an

       ALTER TABLE DROP COLUMN can be used to drop the only column of a table,
       leaving a zero-column table. This is an extension of SQL, which
       disallows zero-column tables.


PostgreSQL 9.2.7		  2014-02-17			ALTER TABLE(7)

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