1CREATE FOREIGN TABLE(7)  PostgreSQL 10.7 Documentation CREATE FOREIGN TABLE(7)
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NAME

6       CREATE_FOREIGN_TABLE - define a new foreign table
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SYNOPSIS

9       CREATE FOREIGN TABLE [ IF NOT EXISTS ] table_name ( [
10         { column_name data_type [ OPTIONS ( option 'value' [, ... ] ) ] [ COLLATE collation ] [ column_constraint [ ... ] ]
11           | table_constraint }
12           [, ... ]
13       ] )
14       [ INHERITS ( parent_table [, ... ] ) ]
15         SERVER server_name
16       [ OPTIONS ( option 'value' [, ... ] ) ]
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18       CREATE FOREIGN TABLE [ IF NOT EXISTS ] table_name
19         PARTITION OF parent_table [ (
20         { column_name [ WITH OPTIONS ] [ column_constraint [ ... ] ]
21           | table_constraint }
22           [, ... ]
23       ) ] partition_bound_spec
24         SERVER server_name
25       [ OPTIONS ( option 'value' [, ... ] ) ]
26
27       where column_constraint is:
28
29       [ CONSTRAINT constraint_name ]
30       { NOT NULL |
31         NULL |
32         CHECK ( expression ) [ NO INHERIT ] |
33         DEFAULT default_expr }
34
35       and table_constraint is:
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37       [ CONSTRAINT constraint_name ]
38       CHECK ( expression ) [ NO INHERIT ]
39

DESCRIPTION

41       CREATE FOREIGN TABLE creates a new foreign table in the current
42       database. The table will be owned by the user issuing the command.
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44       If a schema name is given (for example, CREATE FOREIGN TABLE
45       myschema.mytable ...) then the table is created in the specified
46       schema. Otherwise it is created in the current schema. The name of the
47       foreign table must be distinct from the name of any other foreign
48       table, table, sequence, index, view, or materialized view in the same
49       schema.
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51       CREATE FOREIGN TABLE also automatically creates a data type that
52       represents the composite type corresponding to one row of the foreign
53       table. Therefore, foreign tables cannot have the same name as any
54       existing data type in the same schema.
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56       If PARTITION OF clause is specified then the table is created as a
57       partition of parent_table with specified bounds.
58
59       To be able to create a foreign table, you must have USAGE privilege on
60       the foreign server, as well as USAGE privilege on all column types used
61       in the table.
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PARAMETERS

64       IF NOT EXISTS
65           Do not throw an error if a relation with the same name already
66           exists. A notice is issued in this case. Note that there is no
67           guarantee that the existing relation is anything like the one that
68           would have been created.
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70       table_name
71           The name (optionally schema-qualified) of the table to be created.
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73       column_name
74           The name of a column to be created in the new table.
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76       data_type
77           The data type of the column. This can include array specifiers. For
78           more information on the data types supported by PostgreSQL, refer
79           to Chapter 8.
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81       COLLATE collation
82           The COLLATE clause assigns a collation to the column (which must be
83           of a collatable data type). If not specified, the column data
84           type's default collation is used.
85
86       INHERITS ( parent_table [, ... ] )
87           The optional INHERITS clause specifies a list of tables from which
88           the new foreign table automatically inherits all columns. Parent
89           tables can be plain tables or foreign tables. See the similar form
90           of CREATE TABLE (CREATE_TABLE(7)) for more details.
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92       CONSTRAINT constraint_name
93           An optional name for a column or table constraint. If the
94           constraint is violated, the constraint name is present in error
95           messages, so constraint names like col must be positive can be used
96           to communicate helpful constraint information to client
97           applications. (Double-quotes are needed to specify constraint names
98           that contain spaces.) If a constraint name is not specified, the
99           system generates a name.
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101       NOT NULL
102           The column is not allowed to contain null values.
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104       NULL
105           The column is allowed to contain null values. This is the default.
106
107           This clause is only provided for compatibility with non-standard
108           SQL databases. Its use is discouraged in new applications.
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110       CHECK ( expression ) [ NO INHERIT ]
111           The CHECK clause specifies an expression producing a Boolean result
112           which each row in the foreign table is expected to satisfy; that
113           is, the expression should produce TRUE or UNKNOWN, never FALSE, for
114           all rows in the foreign table. A check constraint specified as a
115           column constraint should reference that column's value only, while
116           an expression appearing in a table constraint can reference
117           multiple columns.
118
119           Currently, CHECK expressions cannot contain subqueries nor refer to
120           variables other than columns of the current row. The system column
121           tableoid may be referenced, but not any other system column.
122
123           A constraint marked with NO INHERIT will not propagate to child
124           tables.
125
126       DEFAULT default_expr
127           The DEFAULT clause assigns a default data value for the column
128           whose column definition it appears within. The value is any
129           variable-free expression (subqueries and cross-references to other
130           columns in the current table are not allowed). The data type of the
131           default expression must match the data type of the column.
132
133           The default expression will be used in any insert operation that
134           does not specify a value for the column. If there is no default for
135           a column, then the default is null.
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137       server_name
138           The name of an existing foreign server to use for the foreign
139           table. For details on defining a server, see CREATE SERVER
140           (CREATE_SERVER(7)).
141
142       OPTIONS ( option 'value' [, ...] )
143           Options to be associated with the new foreign table or one of its
144           columns. The allowed option names and values are specific to each
145           foreign data wrapper and are validated using the foreign-data
146           wrapper's validator function. Duplicate option names are not
147           allowed (although it's OK for a table option and a column option to
148           have the same name).
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NOTES

151       Constraints on foreign tables (such as CHECK or NOT NULL clauses) are
152       not enforced by the core PostgreSQL system, and most foreign data
153       wrappers do not attempt to enforce them either; that is, the constraint
154       is simply assumed to hold true. There would be little point in such
155       enforcement since it would only apply to rows inserted or updated via
156       the foreign table, and not to rows modified by other means, such as
157       directly on the remote server. Instead, a constraint attached to a
158       foreign table should represent a constraint that is being enforced by
159       the remote server.
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161       Some special-purpose foreign data wrappers might be the only access
162       mechanism for the data they access, and in that case it might be
163       appropriate for the foreign data wrapper itself to perform constraint
164       enforcement. But you should not assume that a wrapper does that unless
165       its documentation says so.
166
167       Although PostgreSQL does not attempt to enforce constraints on foreign
168       tables, it does assume that they are correct for purposes of query
169       optimization. If there are rows visible in the foreign table that do
170       not satisfy a declared constraint, queries on the table might produce
171       incorrect answers. It is the user's responsibility to ensure that the
172       constraint definition matches reality.
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EXAMPLES

175       Create foreign table films, which will be accessed through the server
176       film_server:
177
178           CREATE FOREIGN TABLE films (
179               code        char(5) NOT NULL,
180               title       varchar(40) NOT NULL,
181               did         integer NOT NULL,
182               date_prod   date,
183               kind        varchar(10),
184               len         interval hour to minute
185           )
186           SERVER film_server;
187
188       Create foreign table measurement_y2016m07, which will be accessed
189       through the server server_07, as a partition of the range partitioned
190       table measurement:
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192           CREATE FOREIGN TABLE measurement_y2016m07
193               PARTITION OF measurement FOR VALUES FROM ('2016-07-01') TO ('2016-08-01')
194               SERVER server_07;
195

COMPATIBILITY

197       The CREATE FOREIGN TABLE command largely conforms to the SQL standard;
198       however, much as with CREATE TABLE, NULL constraints and zero-column
199       foreign tables are permitted. The ability to specify column default
200       values is also a PostgreSQL extension. Table inheritance, in the form
201       defined by PostgreSQL, is nonstandard.
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SEE ALSO

204       ALTER FOREIGN TABLE (ALTER_FOREIGN_TABLE(7)), DROP FOREIGN TABLE
205       (DROP_FOREIGN_TABLE(7)), CREATE TABLE (CREATE_TABLE(7)), CREATE SERVER
206       (CREATE_SERVER(7)), IMPORT FOREIGN SCHEMA (IMPORT_FOREIGN_SCHEMA(7))
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210PostgreSQL 10.7                      2019              CREATE FOREIGN TABLE(7)
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