Question 108660 in PostgreSQL Question posted in
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Postgresql – How to define a user defined function in AGE

I want to create a customized function that takes multiple parameters, in terms of calling it using my name space here I followed the link here, but still didn’t get the formula to create a schema of the function

I have tried to install langugae cypher using the extension of CREATE EXTENSION plpython3u

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2

Answers


  1. 0

    You have to follow this Setup for Apache AGE, and post installation you use the following commands:

    CREATE EXTENSION age;
LOAD 'age';
SET search_path = ag_catalog, "$user", public;

    Then, you can create your function using this example, from here:

    CREATE OR REPLACE FUNCTION public.get_event_year(name agtype) RETURNS agtype AS $$
    SELECT year::agtype
    FROM history AS h
    WHERE h.event_name = name::text
    LIMIT 1;
$$ LANGUAGE sql;
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  2. 0

    Function with arguments:

    CREATE OR REPLACE FUNCTION pg_catalog.is_in_list(list agtype, size agtype, what agtype)
    RETURNS boolean AS $$
    BEGIN
      FOR i IN 0..size-1 LOOP
         IF list->i = what
         THEN
            RETURN TRUE;
         END IF;
      END LOOP;
    RETURN FALSE;
    END;
    $$ LANGUAGE plpgsql;

    Calling function:

    SELECT * FROM cypher('muse', $$
MATCH (record:jazz)
WHERE pg_catalog.is_in_list(record.tags, size(record.tags), 'mellow')
RETURN record
$$) as (record agtype);

    Example node:

    SELECT * FROM cypher('muse', $$
CREATE(r: jazz {
name: 'Kind of Blue',
artist: 'Miles Davis',
date: '17 August 1959',
sub_genre: ['Modal Jazz', 'Cool Jazz'],
tags: ['instrumental', 'mellow', 'nocturnal', 'soothing', 'improvisation', 'progressive', 'calm'],
rating: 4.31
}) RETURN r
$$) as (jazz_record agtype);

    You can create custom functions without arguments like this:

    CREATE OR REPLACE FUNCTION pg_catalog.current_timestamp_components()
RETURNS TEXT AS $$
DECLARE
  ts_text TEXT;
BEGIN
  SELECT to_char(current_timestamp, 'YYYY-MM-DD HH24:MI:SS') INTO ts_text;
  RETURN ts_text;
END;
$$ LANGUAGE plpgsql;

    Calling function:

    SELECT *
FROM cypher('graph', $$
    CREATE (:Person {name: 'Time', title: 'Developer', time: pg_catalog.current_timestamp_components()})
$$) as (n agtype);

    Helpful link: How to MATCH within a list from vertices using Cypher queries?

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