Postgres-XC 1.1 Documentation
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# dblink_get_pkey

## Name

dblink_get_pkey -- returns the positions and field names of a relation's primary key fields

## Synopsis

    dblink_get_pkey(text relname) returns setof dblink_pkey_results

## Description

> Note: The following description applies only to Postgres-XC

`dblink` module has not been tested with Postges-XC yet. Although there're no reason that `dblink` does not run in Postgres-XC, the development team leaves the test and the use of this module entirely to users.

This section is identical to the corresponding PostgreSQL reference manual.

> Note: The following description applies only to PostgreSQL

`dblink_get_pkey` provides information about the primary key of a relation in the local database. This is sometimes useful in generating queries to be sent to remote databases.

## Arguments

> Note: The following description applies only to Postgres-XC

`dblink` module has not been tested with Postges-XC yet. Although there're no reason that `dblink` does not run in Postgres-XC, the development team leaves the test and the use of this module entirely to users.

This section is identical to the corresponding PostgreSQL reference manual.

> Note: The following description applies only to PostgreSQL

`relname`

  Name of a local relation, for example `foo` or `myschema.mytab`. Include double quotes if the name is mixed-case or contains special characters, for example `"FooBar"`; without quotes, the string will be folded to lower case.

## Return Value

> Note: The following description applies only to Postgres-XC

`dblink` module has not been tested with Postges-XC yet. Although there're no reason that `dblink` does not run in Postgres-XC, the development team leaves the test and the use of this module entirely to users.

This section is identical to the corresponding PostgreSQL reference manual.

> Note: The following description applies only to PostgreSQL

Returns one row for each primary key field, or no rows if the relation has no primary key. The result row type is defined as

    CREATE TYPE dblink_pkey_results AS (position int, colname text);

The `position` column simply runs from 1 to `N`; it is the number of the field within the primary key, not the number within the table's columns.

## Examples

> Note: The following description applies only to Postgres-XC

`dblink` module has not been tested with Postges-XC yet. Although there're no reason that `dblink` does not run in Postgres-XC, the development team leaves the test and the use of this module entirely to users.

This section is identical to the corresponding PostgreSQL reference manual.

> Note: The following description applies only to PostgreSQL

    CREATE TABLE foobar (
        f1 int,
        f2 int,
        f3 int,
        PRIMARY KEY (f1, f2, f3)
    );
    CREATE TABLE

    SELECT * FROM dblink_get_pkey('foobar');
     position | colname
    ----------+---------
            1 | f1
            2 | f2
            3 | f3
    (3 rows)

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