# dblink\_get\_pkey 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) ``` --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.postgresql.tw/appendixes/additional-supplied-modules/dblink/dblink_get_pkey.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.