![]() ![]() The allowed option names and values are specific to each foreign data wrapper and are validated using the foreign-data wrapper's validator function. Options to be associated with the new foreign table or one of its columns. ![]() For details on defining a server, see CREATE SERVER. The name of an existing foreign server to use for the foreign table. References to other tables are not allowed. Any functions and operators used must be immutable. The generation expression can refer to other columns in the table, but not other generated columns. (The computed value will be presented to the foreign-data wrapper for storage and must be returned on reading.) The keyword STORED is required to signify that the column will be computed on write. The column cannot be written to, and when read the result of the specified expression will be returned. This clause creates the column as a generated column. GENERATED ALWAYS AS ( generation_expr ) STORED If there is no default for a column, then the default is null. The default expression will be used in any insert operation that does not specify a value for the column. The data type of the default expression must match the data type of the column. The value is any variable-free expression (subqueries and cross-references to other columns in the current table are not allowed). The DEFAULT clause assigns a default data value for the column whose column definition it appears within. The system column tableoid may be referenced, but not any other system column.Ī constraint marked with NO INHERIT will not propagate to child tables. 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.Ĭurrently, CHECK expressions cannot contain subqueries nor refer to variables other than columns of the current row. The CHECK clause specifies an expression producing a Boolean result which each row in the foreign table is expected to satisfy that is, the expression should produce TRUE or UNKNOWN, never FALSE, for all rows in the foreign table. ![]() Its use is discouraged in new applications. This clause is only provided for compatibility with non-standard SQL databases. The column is allowed to contain null values. The column is not allowed to contain null values. (Double-quotes are needed to specify constraint names that contain spaces.) If a constraint name is not specified, the system generates a name. 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. (See also ALTER TABLE ATTACH PARTITION.) CONSTRAINT constraint_nameĪn optional name for a column or table constraint. Note that it is currently not allowed to create the foreign table as a partition of the parent table if there are UNIQUE indexes on the parent table. ![]() See the similar form of CREATE TABLE for more details. This form can be used to create the foreign table as partition of the given parent table with specified partition bound values. ![]()
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