PostgreSQL 9.4.11 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

`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

`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

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

    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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