Provided by: postgresql-client-11_11.5-1_amd64 bug

NAME

       CREATE_TABLE - define a new table

SYNOPSIS

       CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXISTS ] table_name ( [
         { column_name data_type [ COLLATE collation ] [ column_constraint [ ... ] ]
           | table_constraint
           | LIKE source_table [ like_option ... ] }
           [, ... ]
       ] )
       [ INHERITS ( parent_table [, ... ] ) ]
       [ PARTITION BY { RANGE | LIST | HASH } ( { column_name | ( expression ) } [ COLLATE collation ] [ opclass ] [, ... ] ) ]
       [ WITH ( storage_parameter [= value] [, ... ] ) | WITH OIDS | WITHOUT OIDS ]
       [ ON COMMIT { PRESERVE ROWS | DELETE ROWS | DROP } ]
       [ TABLESPACE tablespace_name ]

       CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXISTS ] table_name
           OF type_name [ (
         { column_name [ WITH OPTIONS ] [ column_constraint [ ... ] ]
           | table_constraint }
           [, ... ]
       ) ]
       [ PARTITION BY { RANGE | LIST | HASH } ( { column_name | ( expression ) } [ COLLATE collation ] [ opclass ] [, ... ] ) ]
       [ WITH ( storage_parameter [= value] [, ... ] ) | WITH OIDS | WITHOUT OIDS ]
       [ ON COMMIT { PRESERVE ROWS | DELETE ROWS | DROP } ]
       [ TABLESPACE tablespace_name ]

       CREATE [ [ GLOBAL | LOCAL ] { TEMPORARY | TEMP } | UNLOGGED ] TABLE [ IF NOT EXISTS ] table_name
           PARTITION OF parent_table [ (
         { column_name [ WITH OPTIONS ] [ column_constraint [ ... ] ]
           | table_constraint }
           [, ... ]
       ) ] { FOR VALUES partition_bound_spec | DEFAULT }
       [ PARTITION BY { RANGE | LIST | HASH } ( { column_name | ( expression ) } [ COLLATE collation ] [ opclass ] [, ... ] ) ]
       [ WITH ( storage_parameter [= value] [, ... ] ) | WITH OIDS | WITHOUT OIDS ]
       [ ON COMMIT { PRESERVE ROWS | DELETE ROWS | DROP } ]
       [ TABLESPACE tablespace_name ]

       where column_constraint is:

       [ CONSTRAINT constraint_name ]
       { NOT NULL |
         NULL |
         CHECK ( expression ) [ NO INHERIT ] |
         DEFAULT default_expr |
         GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( sequence_options ) ] |
         UNIQUE index_parameters |
         PRIMARY KEY index_parameters |
         REFERENCES reftable [ ( refcolumn ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
           [ ON DELETE action ] [ ON UPDATE action ] }
       [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]

       and table_constraint is:

       [ CONSTRAINT constraint_name ]
       { CHECK ( expression ) [ NO INHERIT ] |
         UNIQUE ( column_name [, ... ] ) index_parameters |
         PRIMARY KEY ( column_name [, ... ] ) index_parameters |
         EXCLUDE [ USING index_method ] ( exclude_element WITH operator [, ... ] ) index_parameters [ WHERE ( predicate ) ] |
         FOREIGN KEY ( column_name [, ... ] ) REFERENCES reftable [ ( refcolumn [, ... ] ) ]
           [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ] [ ON DELETE action ] [ ON UPDATE action ] }
       [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]

       and like_option is:

       { INCLUDING | EXCLUDING } { COMMENTS | CONSTRAINTS | DEFAULTS | IDENTITY | INDEXES | STATISTICS | STORAGE | ALL }

       and partition_bound_spec is:

       IN ( { numeric_literal | string_literal | TRUE | FALSE | NULL } [, ...] ) |
       FROM ( { numeric_literal | string_literal | TRUE | FALSE | MINVALUE | MAXVALUE } [, ...] )
         TO ( { numeric_literal | string_literal | TRUE | FALSE | MINVALUE | MAXVALUE } [, ...] ) |
       WITH ( MODULUS numeric_literal, REMAINDER numeric_literal )

       index_parameters in UNIQUE, PRIMARY KEY, and EXCLUDE constraints are:

       [ INCLUDE ( column_name [, ... ] ) ]
       [ WITH ( storage_parameter [= value] [, ... ] ) ]
       [ USING INDEX TABLESPACE tablespace_name ]

       exclude_element in an EXCLUDE constraint is:

       { column_name | ( expression ) } [ opclass ] [ ASC | DESC ] [ NULLS { FIRST | LAST } ]

DESCRIPTION

       CREATE TABLE will create a new, initially empty table in the current database. The table
       will be owned by the user issuing the command.

       If a schema name is given (for example, CREATE TABLE myschema.mytable ...) then the table
       is created in the specified schema. Otherwise it is created in the current schema.
       Temporary tables exist in a special schema, so a schema name cannot be given when creating
       a temporary table. The name of the table must be distinct from the name of any other
       table, sequence, index, view, or foreign table in the same schema.

       CREATE TABLE also automatically creates a data type that represents the composite type
       corresponding to one row of the table. Therefore, tables cannot have the same name as any
       existing data type in the same schema.

       The optional constraint clauses specify constraints (tests) that new or updated rows must
       satisfy for an insert or update operation to succeed. A constraint is an SQL object that
       helps define the set of valid values in the table in various ways.

       There are two ways to define constraints: table constraints and column constraints. A
       column constraint is defined as part of a column definition. A table constraint definition
       is not tied to a particular column, and it can encompass more than one column. Every
       column constraint can also be written as a table constraint; a column constraint is only a
       notational convenience for use when the constraint only affects one column.

       To be able to create a table, you must have USAGE privilege on all column types or the
       type in the OF clause, respectively.

PARAMETERS

       TEMPORARY or TEMP
           If specified, the table is created as a temporary table. Temporary tables are
           automatically dropped at the end of a session, or optionally at the end of the current
           transaction (see ON COMMIT below). Existing permanent tables with the same name are
           not visible to the current session while the temporary table exists, unless they are
           referenced with schema-qualified names. Any indexes created on a temporary table are
           automatically temporary as well.

           The autovacuum daemon cannot access and therefore cannot vacuum or analyze temporary
           tables. For this reason, appropriate vacuum and analyze operations should be performed
           via session SQL commands. For example, if a temporary table is going to be used in
           complex queries, it is wise to run ANALYZE on the temporary table after it is
           populated.

           Optionally, GLOBAL or LOCAL can be written before TEMPORARY or TEMP. This presently
           makes no difference in PostgreSQL and is deprecated; see COMPATIBILITY.

       UNLOGGED
           If specified, the table is created as an unlogged table. Data written to unlogged
           tables is not written to the write-ahead log (see Chapter 30), which makes them
           considerably faster than ordinary tables. However, they are not crash-safe: an
           unlogged table is automatically truncated after a crash or unclean shutdown. The
           contents of an unlogged table are also not replicated to standby servers. Any indexes
           created on an unlogged table are automatically unlogged as well.

       IF NOT EXISTS
           Do not throw an error if a relation with the same name already exists. A notice is
           issued in this case. Note that there is no guarantee that the existing relation is
           anything like the one that would have been created.

       table_name
           The name (optionally schema-qualified) of the table to be created.

       OF type_name
           Creates a typed table, which takes its structure from the specified composite type
           (name optionally schema-qualified). A typed table is tied to its type; for example the
           table will be dropped if the type is dropped (with DROP TYPE ... CASCADE).

           When a typed table is created, then the data types of the columns are determined by
           the underlying composite type and are not specified by the CREATE TABLE command. But
           the CREATE TABLE command can add defaults and constraints to the table and can specify
           storage parameters.

       column_name
           The name of a column to be created in the new table.

       data_type
           The data type of the column. This can include array specifiers. For more information
           on the data types supported by PostgreSQL, refer to Chapter 8.

       COLLATE collation
           The COLLATE clause assigns a collation to the column (which must be of a collatable
           data type). If not specified, the column data type's default collation is used.

       INHERITS ( parent_table [, ... ] )
           The optional INHERITS clause specifies a list of tables from which the new table
           automatically inherits all columns. Parent tables can be plain tables or foreign
           tables.

           Use of INHERITS creates a persistent relationship between the new child table and its
           parent table(s). Schema modifications to the parent(s) normally propagate to children
           as well, and by default the data of the child table is included in scans of the
           parent(s).

           If the same column name exists in more than one parent table, an error is reported
           unless the data types of the columns match in each of the parent tables. If there is
           no conflict, then the duplicate columns are merged to form a single column in the new
           table. If the column name list of the new table contains a column name that is also
           inherited, the data type must likewise match the inherited column(s), and the column
           definitions are merged into one. If the new table explicitly specifies a default value
           for the column, this default overrides any defaults from inherited declarations of the
           column. Otherwise, any parents that specify default values for the column must all
           specify the same default, or an error will be reported.

           CHECK constraints are merged in essentially the same way as columns: if multiple
           parent tables and/or the new table definition contain identically-named CHECK
           constraints, these constraints must all have the same check expression, or an error
           will be reported. Constraints having the same name and expression will be merged into
           one copy. A constraint marked NO INHERIT in a parent will not be considered. Notice
           that an unnamed CHECK constraint in the new table will never be merged, since a unique
           name will always be chosen for it.

           Column STORAGE settings are also copied from parent tables.

           If a column in the parent table is an identity column, that property is not inherited.
           A column in the child table can be declared identity column if desired.

       PARTITION BY { RANGE | LIST | HASH } ( { column_name | ( expression ) } [ opclass ] [,
       ...] )
           The optional PARTITION BY clause specifies a strategy of partitioning the table. The
           table thus created is called a partitioned table. The parenthesized list of columns or
           expressions forms the partition key for the table. When using range or hash
           partitioning, the partition key can include multiple columns or expressions (up to 32,
           but this limit can be altered when building PostgreSQL), but for list partitioning,
           the partition key must consist of a single column or expression.

           Range and list partitioning require a btree operator class, while hash partitioning
           requires a hash operator class. If no operator class is specified explicitly, the
           default operator class of the appropriate type will be used; if no default operator
           class exists, an error will be raised. When hash partitioning is used, the operator
           class used must implement support function 2 (see Section 38.15.3 for details).

           A partitioned table is divided into sub-tables (called partitions), which are created
           using separate CREATE TABLE commands. The partitioned table is itself empty. A data
           row inserted into the table is routed to a partition based on the value of columns or
           expressions in the partition key. If no existing partition matches the values in the
           new row, an error will be reported.

           Partitioned tables do not support EXCLUDE constraints; however, you can define these
           constraints on individual partitions. Also, while it's possible to define PRIMARY KEY
           constraints on partitioned tables, creating foreign keys that reference a partitioned
           table is not yet supported.

           See Section 5.10 for more discussion on table partitioning.

       PARTITION OF parent_table { FOR VALUES partition_bound_spec | DEFAULT }
           Creates the table as a partition of the specified parent table. The table can be
           created either as a partition for specific values using FOR VALUES or as a default
           partition using DEFAULT. This option is not available for hash-partitioned tables.

           The partition_bound_spec must correspond to the partitioning method and partition key
           of the parent table, and must not overlap with any existing partition of that parent.
           The form with IN is used for list partitioning, the form with FROM and TO is used for
           range partitioning, and the form with WITH is used for hash partitioning.

           Each of the values specified in the partition_bound_spec is a literal, NULL, MINVALUE,
           or MAXVALUE. Each literal value must be either a numeric constant that is coercible to
           the corresponding partition key column's type, or a string literal that is valid input
           for that type.

           When creating a list partition, NULL can be specified to signify that the partition
           allows the partition key column to be null. However, there cannot be more than one
           such list partition for a given parent table.  NULL cannot be specified for range
           partitions.

           When creating a range partition, the lower bound specified with FROM is an inclusive
           bound, whereas the upper bound specified with TO is an exclusive bound. That is, the
           values specified in the FROM list are valid values of the corresponding partition key
           columns for this partition, whereas those in the TO list are not. Note that this
           statement must be understood according to the rules of row-wise comparison
           (Section 9.23.5). For example, given PARTITION BY RANGE (x,y), a partition bound FROM
           (1, 2) TO (3, 4) allows x=1 with any y>=2, x=2 with any non-null y, and x=3 with any
           y<4.

           The special values MINVALUE and MAXVALUE may be used when creating a range partition
           to indicate that there is no lower or upper bound on the column's value. For example,
           a partition defined using FROM (MINVALUE) TO (10) allows any values less than 10, and
           a partition defined using FROM (10) TO (MAXVALUE) allows any values greater than or
           equal to 10.

           When creating a range partition involving more than one column, it can also make sense
           to use MAXVALUE as part of the lower bound, and MINVALUE as part of the upper bound.
           For example, a partition defined using FROM (0, MAXVALUE) TO (10, MAXVALUE) allows any
           rows where the first partition key column is greater than 0 and less than or equal to
           10. Similarly, a partition defined using FROM ('a', MINVALUE) TO ('b', MINVALUE)
           allows any rows where the first partition key column starts with "a".

           Note that if MINVALUE or MAXVALUE is used for one column of a partitioning bound, the
           same value must be used for all subsequent columns. For example, (10, MINVALUE, 0) is
           not a valid bound; you should write (10, MINVALUE, MINVALUE).

           Also note that some element types, such as timestamp, have a notion of "infinity",
           which is just another value that can be stored. This is different from MINVALUE and
           MAXVALUE, which are not real values that can be stored, but rather they are ways of
           saying that the value is unbounded.  MAXVALUE can be thought of as being greater than
           any other value, including "infinity" and MINVALUE as being less than any other value,
           including "minus infinity". Thus the range FROM ('infinity') TO (MAXVALUE) is not an
           empty range; it allows precisely one value to be stored — "infinity".

           If DEFAULT is specified, the table will be created as a default partition of the
           parent table. The parent can either be a list or range partitioned table. A partition
           key value not fitting into any other partition of the given parent will be routed to
           the default partition. There can be only one default partition for a given parent
           table.

           When a table has an existing DEFAULT partition and a new partition is added to it, the
           existing default partition must be scanned to verify that it does not contain any rows
           which properly belong in the new partition. If the default partition contains a large
           number of rows, this may be slow. The scan will be skipped if the default partition is
           a foreign table or if it has a constraint which proves that it cannot contain rows
           which should be placed in the new partition.

           When creating a hash partition, a modulus and remainder must be specified. The modulus
           must be a positive integer, and the remainder must be a non-negative integer less than
           the modulus. Typically, when initially setting up a hash-partitioned table, you should
           choose a modulus equal to the number of partitions and assign every table the same
           modulus and a different remainder (see examples, below). However, it is not required
           that every partition have the same modulus, only that every modulus which occurs among
           the partitions of a hash-partitioned table is a factor of the next larger modulus.
           This allows the number of partitions to be increased incrementally without needing to
           move all the data at once. For example, suppose you have a hash-partitioned table with
           8 partitions, each of which has modulus 8, but find it necessary to increase the
           number of partitions to 16. You can detach one of the modulus-8 partitions, create two
           new modulus-16 partitions covering the same portion of the key space (one with a
           remainder equal to the remainder of the detached partition, and the other with a
           remainder equal to that value plus 8), and repopulate them with data. You can then
           repeat this -- perhaps at a later time -- for each modulus-8 partition until none
           remain. While this may still involve a large amount of data movement at each step, it
           is still better than having to create a whole new table and move all the data at once.

           A partition must have the same column names and types as the partitioned table to
           which it belongs. If the parent is specified WITH OIDS then all partitions must have
           OIDs; the parent's OID column will be inherited by all partitions just like any other
           column. Modifications to the column names or types of a partitioned table, or the
           addition or removal of an OID column, will automatically propagate to all partitions.
           CHECK constraints will be inherited automatically by every partition, but an
           individual partition may specify additional CHECK constraints; additional constraints
           with the same name and condition as in the parent will be merged with the parent
           constraint. Defaults may be specified separately for each partition.

           Rows inserted into a partitioned table will be automatically routed to the correct
           partition. If no suitable partition exists, an error will occur.

           Operations such as TRUNCATE which normally affect a table and all of its inheritance
           children will cascade to all partitions, but may also be performed on an individual
           partition. Note that dropping a partition with DROP TABLE requires taking an ACCESS
           EXCLUSIVE lock on the parent table.

       LIKE source_table [ like_option ... ]
           The LIKE clause specifies a table from which the new table automatically copies all
           column names, their data types, and their not-null constraints.

           Unlike INHERITS, the new table and original table are completely decoupled after
           creation is complete. Changes to the original table will not be applied to the new
           table, and it is not possible to include data of the new table in scans of the
           original table.

           Default expressions for the copied column definitions will be copied only if INCLUDING
           DEFAULTS is specified. The default behavior is to exclude default expressions,
           resulting in the copied columns in the new table having null defaults. Note that
           copying defaults that call database-modification functions, such as nextval, may
           create a functional linkage between the original and new tables.

           Any identity specifications of copied column definitions will only be copied if
           INCLUDING IDENTITY is specified. A new sequence is created for each identity column of
           the new table, separate from the sequences associated with the old table.

           Not-null constraints are always copied to the new table.  CHECK constraints will be
           copied only if INCLUDING CONSTRAINTS is specified. No distinction is made between
           column constraints and table constraints.

           Extended statistics are copied to the new table if INCLUDING STATISTICS is specified.

           Indexes, PRIMARY KEY, UNIQUE, and EXCLUDE constraints on the original table will be
           created on the new table only if INCLUDING INDEXES is specified. Names for the new
           indexes and constraints are chosen according to the default rules, regardless of how
           the originals were named. (This behavior avoids possible duplicate-name failures for
           the new indexes.)

           STORAGE settings for the copied column definitions will be copied only if INCLUDING
           STORAGE is specified. The default behavior is to exclude STORAGE settings, resulting
           in the copied columns in the new table having type-specific default settings. For more
           on STORAGE settings, see Section 68.2.

           Comments for the copied columns, constraints, and indexes will be copied only if
           INCLUDING COMMENTS is specified. The default behavior is to exclude comments,
           resulting in the copied columns and constraints in the new table having no comments.

           INCLUDING ALL is an abbreviated form of INCLUDING COMMENTS INCLUDING CONSTRAINTS
           INCLUDING DEFAULTS INCLUDING IDENTITY INCLUDING INDEXES INCLUDING STATISTICS INCLUDING
           STORAGE.

           Note that unlike INHERITS, columns and constraints copied by LIKE are not merged with
           similarly named columns and constraints. If the same name is specified explicitly or
           in another LIKE clause, an error is signaled.

           The LIKE clause can also be used to copy column definitions from views, foreign
           tables, or composite types. Inapplicable options (e.g., INCLUDING INDEXES from a view)
           are ignored.

       CONSTRAINT constraint_name
           An optional name for a column or table constraint. If the constraint is violated, the
           constraint name is present in error messages, so constraint names like col must be
           positive can be used to communicate helpful constraint information to client
           applications. (Double-quotes are needed to specify constraint names that contain
           spaces.) If a constraint name is not specified, the system generates a name.

       NOT NULL
           The column is not allowed to contain null values.

       NULL
           The column is allowed to contain null values. This is the default.

           This clause is only provided for compatibility with non-standard SQL databases. Its
           use is discouraged in new applications.

       CHECK ( expression ) [ NO INHERIT ]
           The CHECK clause specifies an expression producing a Boolean result which new or
           updated rows must satisfy for an insert or update operation to succeed. Expressions
           evaluating to TRUE or UNKNOWN succeed. Should any row of an insert or update operation
           produce a FALSE result, an error exception is raised and the insert or update does not
           alter the database. A check constraint specified as a column constraint should
           reference that column's value only, while an expression appearing in a table
           constraint can reference multiple columns.

           Currently, CHECK expressions cannot contain subqueries nor refer to variables other
           than columns of the current row. The system column tableoid may be referenced, but not
           any other system column.

           A constraint marked with NO INHERIT will not propagate to child tables.

           When a table has multiple CHECK constraints, they will be tested for each row in
           alphabetical order by name, after checking NOT NULL constraints. (PostgreSQL versions
           before 9.5 did not honor any particular firing order for CHECK constraints.)

       DEFAULT default_expr
           The DEFAULT clause assigns a default data value for the column whose column definition
           it appears within. The value is any variable-free expression (subqueries and
           cross-references to other columns in the current table are not allowed). The data type
           of the default expression must match the data type of the column.

           The default expression will be used in any insert operation that does not specify a
           value for the column. If there is no default for a column, then the default is null.

       GENERATED { ALWAYS | BY DEFAULT } AS IDENTITY [ ( sequence_options ) ]
           This clause creates the column as an identity column. It will have an implicit
           sequence attached to it and the column in new rows will automatically have values from
           the sequence assigned to it.

           The clauses ALWAYS and BY DEFAULT determine how the sequence value is given precedence
           over a user-specified value in an INSERT statement. If ALWAYS is specified, a
           user-specified value is only accepted if the INSERT statement specifies OVERRIDING
           SYSTEM VALUE. If BY DEFAULT is specified, then the user-specified value takes
           precedence. See INSERT(7) for details. (In the COPY command, user-specified values are
           always used regardless of this setting.)

           The optional sequence_options clause can be used to override the options of the
           sequence. See CREATE SEQUENCE (CREATE_SEQUENCE(7)) for details.

       UNIQUE (column constraint)
       UNIQUE ( column_name [, ... ] ) [ INCLUDE ( column_name [, ...]) ] (table constraint)
           The UNIQUE constraint specifies that a group of one or more columns of a table can
           contain only unique values. The behavior of the unique table constraint is the same as
           that for column constraints, with the additional capability to span multiple columns.

           For the purpose of a unique constraint, null values are not considered equal.

           Each unique table constraint must name a set of columns that is different from the set
           of columns named by any other unique or primary key constraint defined for the table.
           (Otherwise it would just be the same constraint listed twice.)

           When establishing a unique constraint for a multi-level partition hierarchy, all the
           columns in the partition key of the target partitioned table, as well as those of all
           its descendant partitioned tables, must be included in the constraint definition.

           Adding a unique constraint will automatically create a unique btree index on the
           column or group of columns used in the constraint. The optional clause INCLUDE adds to
           that index one or more columns on which the uniqueness is not enforced. Note that
           although the constraint is not enforced on the included columns, it still depends on
           them. Consequently, some operations on these columns (e.g.  DROP COLUMN) can cause
           cascaded constraint and index deletion.

       PRIMARY KEY (column constraint)
       PRIMARY KEY ( column_name [, ... ] ) [ INCLUDE ( column_name [, ...]) ] (table constraint)
           The PRIMARY KEY constraint specifies that a column or columns of a table can contain
           only unique (non-duplicate), nonnull values. Only one primary key can be specified for
           a table, whether as a column constraint or a table constraint.

           The primary key constraint should name a set of columns that is different from the set
           of columns named by any unique constraint defined for the same table. (Otherwise, the
           unique constraint is redundant and will be discarded.)

           PRIMARY KEY enforces the same data constraints as a combination of UNIQUE and NOT
           NULL, but identifying a set of columns as the primary key also provides metadata about
           the design of the schema, since a primary key implies that other tables can rely on
           this set of columns as a unique identifier for rows.

           PRIMARY KEY constraints share the restrictions that UNIQUE constraints have when
           placed on partitioned tables.

           Adding a PRIMARY KEY constraint will automatically create a unique btree index on the
           column or group of columns used in the constraint. The optional INCLUDE clause allows
           a list of columns to be specified which will be included in the non-key portion of the
           index. Although uniqueness is not enforced on the included columns, the constraint
           still depends on them. Consequently, some operations on the included columns (e.g.
           DROP COLUMN) can cause cascaded constraint and index deletion.

       EXCLUDE [ USING index_method ] ( exclude_element WITH operator [, ... ] ) index_parameters
       [ WHERE ( predicate ) ]
           The EXCLUDE clause defines an exclusion constraint, which guarantees that if any two
           rows are compared on the specified column(s) or expression(s) using the specified
           operator(s), not all of these comparisons will return TRUE. If all of the specified
           operators test for equality, this is equivalent to a UNIQUE constraint, although an
           ordinary unique constraint will be faster. However, exclusion constraints can specify
           constraints that are more general than simple equality. For example, you can specify a
           constraint that no two rows in the table contain overlapping circles (see Section 8.8)
           by using the && operator.

           Exclusion constraints are implemented using an index, so each specified operator must
           be associated with an appropriate operator class (see Section 11.10) for the index
           access method index_method. The operators are required to be commutative. Each
           exclude_element can optionally specify an operator class and/or ordering options;
           these are described fully under CREATE INDEX (CREATE_INDEX(7)).

           The access method must support amgettuple (see Chapter 61); at present this means GIN
           cannot be used. Although it's allowed, there is little point in using B-tree or hash
           indexes with an exclusion constraint, because this does nothing that an ordinary
           unique constraint doesn't do better. So in practice the access method will always be
           GiST or SP-GiST.

           The predicate allows you to specify an exclusion constraint on a subset of the table;
           internally this creates a partial index. Note that parentheses are required around the
           predicate.

       REFERENCES reftable [ ( refcolumn ) ] [ MATCH matchtype ] [ ON DELETE action ] [ ON UPDATE
       action ] (column constraint)
       FOREIGN KEY ( column_name [, ... ] ) REFERENCES reftable [ ( refcolumn [, ... ] ) ] [
       MATCH matchtype ] [ ON DELETE action ] [ ON UPDATE action ] (table constraint)
           These clauses specify a foreign key constraint, which requires that a group of one or
           more columns of the new table must only contain values that match values in the
           referenced column(s) of some row of the referenced table. If the refcolumn list is
           omitted, the primary key of the reftable is used. The referenced columns must be the
           columns of a non-deferrable unique or primary key constraint in the referenced table.
           The user must have REFERENCES permission on the referenced table (either the whole
           table, or the specific referenced columns). The addition of a foreign key constraint
           requires a SHARE ROW EXCLUSIVE lock on the referenced table. Note that foreign key
           constraints cannot be defined between temporary tables and permanent tables. Also note
           that while it is possible to define a foreign key on a partitioned table, it is not
           possible to declare a foreign key that references a partitioned table.

           A value inserted into the referencing column(s) is matched against the values of the
           referenced table and referenced columns using the given match type. There are three
           match types: MATCH FULL, MATCH PARTIAL, and MATCH SIMPLE (which is the default).
           MATCH FULL will not allow one column of a multicolumn foreign key to be null unless
           all foreign key columns are null; if they are all null, the row is not required to
           have a match in the referenced table.  MATCH SIMPLE allows any of the foreign key
           columns to be null; if any of them are null, the row is not required to have a match
           in the referenced table.  MATCH PARTIAL is not yet implemented. (Of course, NOT NULL
           constraints can be applied to the referencing column(s) to prevent these cases from
           arising.)

           In addition, when the data in the referenced columns is changed, certain actions are
           performed on the data in this table's columns. The ON DELETE clause specifies the
           action to perform when a referenced row in the referenced table is being deleted.
           Likewise, the ON UPDATE clause specifies the action to perform when a referenced
           column in the referenced table is being updated to a new value. If the row is updated,
           but the referenced column is not actually changed, no action is done. Referential
           actions other than the NO ACTION check cannot be deferred, even if the constraint is
           declared deferrable. There are the following possible actions for each clause:

           NO ACTION
               Produce an error indicating that the deletion or update would create a foreign key
               constraint violation. If the constraint is deferred, this error will be produced
               at constraint check time if there still exist any referencing rows. This is the
               default action.

           RESTRICT
               Produce an error indicating that the deletion or update would create a foreign key
               constraint violation. This is the same as NO ACTION except that the check is not
               deferrable.

           CASCADE
               Delete any rows referencing the deleted row, or update the values of the
               referencing column(s) to the new values of the referenced columns, respectively.

           SET NULL
               Set the referencing column(s) to null.

           SET DEFAULT
               Set the referencing column(s) to their default values. (There must be a row in the
               referenced table matching the default values, if they are not null, or the
               operation will fail.)

           If the referenced column(s) are changed frequently, it might be wise to add an index
           to the referencing column(s) so that referential actions associated with the foreign
           key constraint can be performed more efficiently.

       DEFERRABLE
       NOT DEFERRABLE
           This controls whether the constraint can be deferred. A constraint that is not
           deferrable will be checked immediately after every command. Checking of constraints
           that are deferrable can be postponed until the end of the transaction (using the SET
           CONSTRAINTS (SET_CONSTRAINTS(7)) command).  NOT DEFERRABLE is the default. Currently,
           only UNIQUE, PRIMARY KEY, EXCLUDE, and REFERENCES (foreign key) constraints accept
           this clause.  NOT NULL and CHECK constraints are not deferrable. Note that deferrable
           constraints cannot be used as conflict arbitrators in an INSERT statement that
           includes an ON CONFLICT DO UPDATE clause.

       INITIALLY IMMEDIATE
       INITIALLY DEFERRED
           If a constraint is deferrable, this clause specifies the default time to check the
           constraint. If the constraint is INITIALLY IMMEDIATE, it is checked after each
           statement. This is the default. If the constraint is INITIALLY DEFERRED, it is checked
           only at the end of the transaction. The constraint check time can be altered with the
           SET CONSTRAINTS (SET_CONSTRAINTS(7)) command.

       WITH ( storage_parameter [= value] [, ... ] )
           This clause specifies optional storage parameters for a table or index; see Storage
           Parameters for more information. The WITH clause for a table can also include
           OIDS=TRUE (or just OIDS) to specify that rows of the new table should have OIDs
           (object identifiers) assigned to them, or OIDS=FALSE to specify that the rows should
           not have OIDs. If OIDS is not specified, the default setting depends upon the
           default_with_oids configuration parameter. (If the new table inherits from any tables
           that have OIDs, then OIDS=TRUE is forced even if the command says OIDS=FALSE.)

           If OIDS=FALSE is specified or implied, the new table does not store OIDs and no OID
           will be assigned for a row inserted into it. This is generally considered worthwhile,
           since it will reduce OID consumption and thereby postpone the wraparound of the 32-bit
           OID counter. Once the counter wraps around, OIDs can no longer be assumed to be
           unique, which makes them considerably less useful. In addition, excluding OIDs from a
           table reduces the space required to store the table on disk by 4 bytes per row (on
           most machines), slightly improving performance.

           To remove OIDs from a table after it has been created, use ALTER TABLE
           (ALTER_TABLE(7)).

       WITH OIDS
       WITHOUT OIDS
           These are obsolescent syntaxes equivalent to WITH (OIDS) and WITH (OIDS=FALSE),
           respectively. If you wish to give both an OIDS setting and storage parameters, you
           must use the WITH ( ... ) syntax; see above.

       ON COMMIT
           The behavior of temporary tables at the end of a transaction block can be controlled
           using ON COMMIT. The three options are:

           PRESERVE ROWS
               No special action is taken at the ends of transactions. This is the default
               behavior.

           DELETE ROWS
               All rows in the temporary table will be deleted at the end of each transaction
               block. Essentially, an automatic TRUNCATE(7) is done at each commit. When used on
               a partitioned table, this is not cascaded to its partitions.

           DROP
               The temporary table will be dropped at the end of the current transaction block.
               When used on a partitioned table, this action drops its partitions and when used
               on tables with inheritance children, it drops the dependent children.

       TABLESPACE tablespace_name
           The tablespace_name is the name of the tablespace in which the new table is to be
           created. If not specified, default_tablespace is consulted, or temp_tablespaces if the
           table is temporary.

       USING INDEX TABLESPACE tablespace_name
           This clause allows selection of the tablespace in which the index associated with a
           UNIQUE, PRIMARY KEY, or EXCLUDE constraint will be created. If not specified,
           default_tablespace is consulted, or temp_tablespaces if the table is temporary.

   Storage Parameters
       The WITH clause can specify storage parameters for tables, and for indexes associated with
       a UNIQUE, PRIMARY KEY, or EXCLUDE constraint. Storage parameters for indexes are
       documented in CREATE INDEX (CREATE_INDEX(7)). The storage parameters currently available
       for tables are listed below. For many of these parameters, as shown, there is an
       additional parameter with the same name prefixed with toast., which controls the behavior
       of the table's secondary TOAST table, if any (see Section 68.2 for more information about
       TOAST). If a table parameter value is set and the equivalent toast.  parameter is not, the
       TOAST table will use the table's parameter value. Specifying these parameters for
       partitioned tables is not supported, but you may specify them for individual leaf
       partitions.

       fillfactor (integer)
           The fillfactor for a table is a percentage between 10 and 100. 100 (complete packing)
           is the default. When a smaller fillfactor is specified, INSERT operations pack table
           pages only to the indicated percentage; the remaining space on each page is reserved
           for updating rows on that page. This gives UPDATE a chance to place the updated copy
           of a row on the same page as the original, which is more efficient than placing it on
           a different page. For a table whose entries are never updated, complete packing is the
           best choice, but in heavily updated tables smaller fillfactors are appropriate. This
           parameter cannot be set for TOAST tables.

       toast_tuple_target (integer)
           The toast_tuple_target specifies the minimum tuple length required before we try to
           move long column values into TOAST tables, and is also the target length we try to
           reduce the length below once toasting begins. This only affects columns marked as
           either External or Extended and applies only to new tuples - there is no effect on
           existing rows. By default this parameter is set to allow at least 4 tuples per block,
           which with the default blocksize will be 2040 bytes. Valid values are between 128
           bytes and the (blocksize - header), by default 8160 bytes. Changing this value may not
           be useful for very short or very long rows. Note that the default setting is often
           close to optimal, and it is possible that setting this parameter could have negative
           effects in some cases. This parameter cannot be set for TOAST tables.

       parallel_workers (integer)
           This sets the number of workers that should be used to assist a parallel scan of this
           table. If not set, the system will determine a value based on the relation size. The
           actual number of workers chosen by the planner or by utility statements that use
           parallel scans may be less, for example due to the setting of max_worker_processes.

       autovacuum_enabled, toast.autovacuum_enabled (boolean)
           Enables or disables the autovacuum daemon for a particular table. If true, the
           autovacuum daemon will perform automatic VACUUM and/or ANALYZE operations on this
           table following the rules discussed in Section 24.1.6. If false, this table will not
           be autovacuumed, except to prevent transaction ID wraparound. See Section 24.1.5 for
           more about wraparound prevention. Note that the autovacuum daemon does not run at all
           (except to prevent transaction ID wraparound) if the autovacuum parameter is false;
           setting individual tables' storage parameters does not override that. Therefore there
           is seldom much point in explicitly setting this storage parameter to true, only to
           false.

       autovacuum_vacuum_threshold, toast.autovacuum_vacuum_threshold (integer)
           Per-table value for autovacuum_vacuum_threshold parameter.

       autovacuum_vacuum_scale_factor, toast.autovacuum_vacuum_scale_factor (float4)
           Per-table value for autovacuum_vacuum_scale_factor parameter.

       autovacuum_analyze_threshold (integer)
           Per-table value for autovacuum_analyze_threshold parameter.

       autovacuum_analyze_scale_factor (float4)
           Per-table value for autovacuum_analyze_scale_factor parameter.

       autovacuum_vacuum_cost_delay, toast.autovacuum_vacuum_cost_delay (integer)
           Per-table value for autovacuum_vacuum_cost_delay parameter.

       autovacuum_vacuum_cost_limit, toast.autovacuum_vacuum_cost_limit (integer)
           Per-table value for autovacuum_vacuum_cost_limit parameter.

       autovacuum_freeze_min_age, toast.autovacuum_freeze_min_age (integer)
           Per-table value for vacuum_freeze_min_age parameter. Note that autovacuum will ignore
           per-table autovacuum_freeze_min_age parameters that are larger than half the
           system-wide autovacuum_freeze_max_age setting.

       autovacuum_freeze_max_age, toast.autovacuum_freeze_max_age (integer)
           Per-table value for autovacuum_freeze_max_age parameter. Note that autovacuum will
           ignore per-table autovacuum_freeze_max_age parameters that are larger than the
           system-wide setting (it can only be set smaller).

       autovacuum_freeze_table_age, toast.autovacuum_freeze_table_age (integer)
           Per-table value for vacuum_freeze_table_age parameter.

       autovacuum_multixact_freeze_min_age, toast.autovacuum_multixact_freeze_min_age (integer)
           Per-table value for vacuum_multixact_freeze_min_age parameter. Note that autovacuum
           will ignore per-table autovacuum_multixact_freeze_min_age parameters that are larger
           than half the system-wide autovacuum_multixact_freeze_max_age setting.

       autovacuum_multixact_freeze_max_age, toast.autovacuum_multixact_freeze_max_age (integer)
           Per-table value for autovacuum_multixact_freeze_max_age parameter. Note that
           autovacuum will ignore per-table autovacuum_multixact_freeze_max_age parameters that
           are larger than the system-wide setting (it can only be set smaller).

       autovacuum_multixact_freeze_table_age, toast.autovacuum_multixact_freeze_table_age
       (integer)
           Per-table value for vacuum_multixact_freeze_table_age parameter.

       log_autovacuum_min_duration, toast.log_autovacuum_min_duration (integer)
           Per-table value for log_autovacuum_min_duration parameter.

       user_catalog_table (boolean)
           Declare the table as an additional catalog table for purposes of logical replication.
           See Section 49.6.2 for details. This parameter cannot be set for TOAST tables.

NOTES

       Using OIDs in new applications is not recommended: where possible, using an identity
       column or other sequence generator as the table's primary key is preferred. However, if
       your application does make use of OIDs to identify specific rows of a table, it is
       recommended to create a unique constraint on the oid column of that table, to ensure that
       OIDs in the table will indeed uniquely identify rows even after counter wraparound. Avoid
       assuming that OIDs are unique across tables; if you need a database-wide unique
       identifier, use the combination of tableoid and row OID for the purpose.

           Tip
           The use of OIDS=FALSE is not recommended for tables with no primary key, since without
           either an OID or a unique data key, it is difficult to identify specific rows.

       PostgreSQL automatically creates an index for each unique constraint and primary key
       constraint to enforce uniqueness. Thus, it is not necessary to create an index explicitly
       for primary key columns. (See CREATE INDEX (CREATE_INDEX(7)) for more information.)

       Unique constraints and primary keys are not inherited in the current implementation. This
       makes the combination of inheritance and unique constraints rather dysfunctional.

       A table cannot have more than 1600 columns. (In practice, the effective limit is usually
       lower because of tuple-length constraints.)

EXAMPLES

       Create table films and table distributors:

           CREATE TABLE films (
               code        char(5) CONSTRAINT firstkey PRIMARY KEY,
               title       varchar(40) NOT NULL,
               did         integer NOT NULL,
               date_prod   date,
               kind        varchar(10),
               len         interval hour to minute
           );

           CREATE TABLE distributors (
                did    integer PRIMARY KEY GENERATED BY DEFAULT AS IDENTITY,
                name   varchar(40) NOT NULL CHECK (name <> '')
           );

       Create a table with a 2-dimensional array:

           CREATE TABLE array_int (
               vector  int[][]
           );

       Define a unique table constraint for the table films. Unique table constraints can be
       defined on one or more columns of the table:

           CREATE TABLE films (
               code        char(5),
               title       varchar(40),
               did         integer,
               date_prod   date,
               kind        varchar(10),
               len         interval hour to minute,
               CONSTRAINT production UNIQUE(date_prod)
           );

       Define a check column constraint:

           CREATE TABLE distributors (
               did     integer CHECK (did > 100),
               name    varchar(40)
           );

       Define a check table constraint:

           CREATE TABLE distributors (
               did     integer,
               name    varchar(40),
               CONSTRAINT con1 CHECK (did > 100 AND name <> '')
           );

       Define a primary key table constraint for the table films:

           CREATE TABLE films (
               code        char(5),
               title       varchar(40),
               did         integer,
               date_prod   date,
               kind        varchar(10),
               len         interval hour to minute,
               CONSTRAINT code_title PRIMARY KEY(code,title)
           );

       Define a primary key constraint for table distributors. The following two examples are
       equivalent, the first using the table constraint syntax, the second the column constraint
       syntax:

           CREATE TABLE distributors (
               did     integer,
               name    varchar(40),
               PRIMARY KEY(did)
           );

           CREATE TABLE distributors (
               did     integer PRIMARY KEY,
               name    varchar(40)
           );

       Assign a literal constant default value for the column name, arrange for the default value
       of column did to be generated by selecting the next value of a sequence object, and make
       the default value of modtime be the time at which the row is inserted:

           CREATE TABLE distributors (
               name      varchar(40) DEFAULT 'Luso Films',
               did       integer DEFAULT nextval('distributors_serial'),
               modtime   timestamp DEFAULT current_timestamp
           );

       Define two NOT NULL column constraints on the table distributors, one of which is
       explicitly given a name:

           CREATE TABLE distributors (
               did     integer CONSTRAINT no_null NOT NULL,
               name    varchar(40) NOT NULL
           );

       Define a unique constraint for the name column:

           CREATE TABLE distributors (
               did     integer,
               name    varchar(40) UNIQUE
           );

       The same, specified as a table constraint:

           CREATE TABLE distributors (
               did     integer,
               name    varchar(40),
               UNIQUE(name)
           );

       Create the same table, specifying 70% fill factor for both the table and its unique index:

           CREATE TABLE distributors (
               did     integer,
               name    varchar(40),
               UNIQUE(name) WITH (fillfactor=70)
           )
           WITH (fillfactor=70);

       Create table circles with an exclusion constraint that prevents any two circles from
       overlapping:

           CREATE TABLE circles (
               c circle,
               EXCLUDE USING gist (c WITH &&)
           );

       Create table cinemas in tablespace diskvol1:

           CREATE TABLE cinemas (
                   id serial,
                   name text,
                   location text
           ) TABLESPACE diskvol1;

       Create a composite type and a typed table:

           CREATE TYPE employee_type AS (name text, salary numeric);

           CREATE TABLE employees OF employee_type (
               PRIMARY KEY (name),
               salary WITH OPTIONS DEFAULT 1000
           );

       Create a range partitioned table:

           CREATE TABLE measurement (
               logdate         date not null,
               peaktemp        int,
               unitsales       int
           ) PARTITION BY RANGE (logdate);

       Create a range partitioned table with multiple columns in the partition key:

           CREATE TABLE measurement_year_month (
               logdate         date not null,
               peaktemp        int,
               unitsales       int
           ) PARTITION BY RANGE (EXTRACT(YEAR FROM logdate), EXTRACT(MONTH FROM logdate));

       Create a list partitioned table:

           CREATE TABLE cities (
               city_id      bigserial not null,
               name         text not null,
               population   bigint
           ) PARTITION BY LIST (left(lower(name), 1));

       Create a hash partitioned table:

           CREATE TABLE orders (
               order_id     bigint not null,
               cust_id      bigint not null,
               status       text
           ) PARTITION BY HASH (order_id);

       Create partition of a range partitioned table:

           CREATE TABLE measurement_y2016m07
               PARTITION OF measurement (
               unitsales DEFAULT 0
           ) FOR VALUES FROM ('2016-07-01') TO ('2016-08-01');

       Create a few partitions of a range partitioned table with multiple columns in the
       partition key:

           CREATE TABLE measurement_ym_older
               PARTITION OF measurement_year_month
               FOR VALUES FROM (MINVALUE, MINVALUE) TO (2016, 11);

           CREATE TABLE measurement_ym_y2016m11
               PARTITION OF measurement_year_month
               FOR VALUES FROM (2016, 11) TO (2016, 12);

           CREATE TABLE measurement_ym_y2016m12
               PARTITION OF measurement_year_month
               FOR VALUES FROM (2016, 12) TO (2017, 01);

           CREATE TABLE measurement_ym_y2017m01
               PARTITION OF measurement_year_month
               FOR VALUES FROM (2017, 01) TO (2017, 02);

       Create partition of a list partitioned table:

           CREATE TABLE cities_ab
               PARTITION OF cities (
               CONSTRAINT city_id_nonzero CHECK (city_id != 0)
           ) FOR VALUES IN ('a', 'b');

       Create partition of a list partitioned table that is itself further partitioned and then
       add a partition to it:

           CREATE TABLE cities_ab
               PARTITION OF cities (
               CONSTRAINT city_id_nonzero CHECK (city_id != 0)
           ) FOR VALUES IN ('a', 'b') PARTITION BY RANGE (population);

           CREATE TABLE cities_ab_10000_to_100000
               PARTITION OF cities_ab FOR VALUES FROM (10000) TO (100000);

       Create partitions of a hash partitioned table:

           CREATE TABLE orders_p1 PARTITION OF orders
               FOR VALUES WITH (MODULUS 4, REMAINDER 0);
           CREATE TABLE orders_p2 PARTITION OF orders
               FOR VALUES WITH (MODULUS 4, REMAINDER 1);
           CREATE TABLE orders_p3 PARTITION OF orders
               FOR VALUES WITH (MODULUS 4, REMAINDER 2);
           CREATE TABLE orders_p4 PARTITION OF orders
               FOR VALUES WITH (MODULUS 4, REMAINDER 3);

       Create a default partition:

           CREATE TABLE cities_partdef
               PARTITION OF cities DEFAULT;

COMPATIBILITY

       The CREATE TABLE command conforms to the SQL standard, with exceptions listed below.

   Temporary Tables
       Although the syntax of CREATE TEMPORARY TABLE resembles that of the SQL standard, the
       effect is not the same. In the standard, temporary tables are defined just once and
       automatically exist (starting with empty contents) in every session that needs them.
       PostgreSQL instead requires each session to issue its own CREATE TEMPORARY TABLE command
       for each temporary table to be used. This allows different sessions to use the same
       temporary table name for different purposes, whereas the standard's approach constrains
       all instances of a given temporary table name to have the same table structure.

       The standard's definition of the behavior of temporary tables is widely ignored.
       PostgreSQL's behavior on this point is similar to that of several other SQL databases.

       The SQL standard also distinguishes between global and local temporary tables, where a
       local temporary table has a separate set of contents for each SQL module within each
       session, though its definition is still shared across sessions. Since PostgreSQL does not
       support SQL modules, this distinction is not relevant in PostgreSQL.

       For compatibility's sake, PostgreSQL will accept the GLOBAL and LOCAL keywords in a
       temporary table declaration, but they currently have no effect. Use of these keywords is
       discouraged, since future versions of PostgreSQL might adopt a more standard-compliant
       interpretation of their meaning.

       The ON COMMIT clause for temporary tables also resembles the SQL standard, but has some
       differences. If the ON COMMIT clause is omitted, SQL specifies that the default behavior
       is ON COMMIT DELETE ROWS. However, the default behavior in PostgreSQL is ON COMMIT
       PRESERVE ROWS. The ON COMMIT DROP option does not exist in SQL.

   Non-deferred Uniqueness Constraints
       When a UNIQUE or PRIMARY KEY constraint is not deferrable, PostgreSQL checks for
       uniqueness immediately whenever a row is inserted or modified. The SQL standard says that
       uniqueness should be enforced only at the end of the statement; this makes a difference
       when, for example, a single command updates multiple key values. To obtain
       standard-compliant behavior, declare the constraint as DEFERRABLE but not deferred (i.e.,
       INITIALLY IMMEDIATE). Be aware that this can be significantly slower than immediate
       uniqueness checking.

   Column Check Constraints
       The SQL standard says that CHECK column constraints can only refer to the column they
       apply to; only CHECK table constraints can refer to multiple columns.  PostgreSQL does not
       enforce this restriction; it treats column and table check constraints alike.

   EXCLUDE Constraint
       The EXCLUDE constraint type is a PostgreSQL extension.

   NULL “Constraint”
       The NULL “constraint” (actually a non-constraint) is a PostgreSQL extension to the SQL
       standard that is included for compatibility with some other database systems (and for
       symmetry with the NOT NULL constraint). Since it is the default for any column, its
       presence is simply noise.

   Constraint Naming
       The SQL standard says that table and domain constraints must have names that are unique
       across the schema containing the table or domain.  PostgreSQL is laxer: it only requires
       constraint names to be unique across the constraints attached to a particular table or
       domain. However, this extra freedom does not exist for index-based constraints (UNIQUE,
       PRIMARY KEY, and EXCLUDE constraints), because the associated index is named the same as
       the constraint, and index names must be unique across all relations within the same
       schema.

       Currently, PostgreSQL does not record names for NOT NULL constraints at all, so they are
       not subject to the uniqueness restriction. This might change in a future release.

   Inheritance
       Multiple inheritance via the INHERITS clause is a PostgreSQL language extension. SQL:1999
       and later define single inheritance using a different syntax and different semantics.
       SQL:1999-style inheritance is not yet supported by PostgreSQL.

   Zero-column Tables
       PostgreSQL allows a table of no columns to be created (for example, CREATE TABLE foo();).
       This is an extension from the SQL standard, which does not allow zero-column tables.
       Zero-column tables are not in themselves very useful, but disallowing them creates odd
       special cases for ALTER TABLE DROP COLUMN, so it seems cleaner to ignore this spec
       restriction.

   Multiple Identity Columns
       PostgreSQL allows a table to have more than one identity column. The standard specifies
       that a table can have at most one identity column. This is relaxed mainly to give more
       flexibility for doing schema changes or migrations. Note that the INSERT command supports
       only one override clause that applies to the entire statement, so having multiple identity
       columns with different behaviors is not well supported.

   LIKE Clause
       While a LIKE clause exists in the SQL standard, many of the options that PostgreSQL
       accepts for it are not in the standard, and some of the standard's options are not
       implemented by PostgreSQL.

   WITH Clause
       The WITH clause is a PostgreSQL extension; neither storage parameters nor OIDs are in the
       standard.

   Tablespaces
       The PostgreSQL concept of tablespaces is not part of the standard. Hence, the clauses
       TABLESPACE and USING INDEX TABLESPACE are extensions.

   Typed Tables
       Typed tables implement a subset of the SQL standard. According to the standard, a typed
       table has columns corresponding to the underlying composite type as well as one other
       column that is the “self-referencing column”. PostgreSQL does not support these
       self-referencing columns explicitly, but the same effect can be had using the OID feature.

   PARTITION BY Clause
       The PARTITION BY clause is a PostgreSQL extension.

   PARTITION OF Clause
       The PARTITION OF clause is a PostgreSQL extension.

SEE ALSO

       ALTER TABLE (ALTER_TABLE(7)), DROP TABLE (DROP_TABLE(7)), CREATE TABLE AS
       (CREATE_TABLE_AS(7)), CREATE TABLESPACE (CREATE_TABLESPACE(7)), CREATE TYPE
       (CREATE_TYPE(7))