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Muhammad Farooq
Muhammad Farooq

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Advanced Tutorial for Cypher (Part 2)

#apacheage #agensgraph #graphdatabase #cypher

This Tutorial is extension of The tutorial Advanced Tutorial for Cypher Part (1)

Create Stored Procedure (1)

You can create Stored Procedure as follows:

  • The fn_array_uniq function enters an array and returns a unique factor.
  • IMMUTABLE represents the classification of the volatility of the procedure. Has the characteristics of calculating and processing returns as constants.
  • STRICT returns a null value whenever the argument is null.
  • The GENERATE_SERIES function takes** (start, stop, step interval)** as input variables and increments and decreases it to the units set in step interval
  • The ARRAY_LOWER / ARRAY_UPPER function returns the lower/upper limit of the array dimension. 
CREATE FUNCTION fn_array_uniq (anyarray) RETURNS anyarray IMMUTABLE STRICT LANGUAGE SQL AS $$ SELECT ARRAY ( SELECT DISTINCT $1[i] FROM GENERATE_SERIES (ARRAY_LOWER($1,1), ARRAY_UPPER($1,1)) AS g(i)); $$;
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Create Stored Procedure (2)

You can create Stored Procedure as follows:

  • Ids is a function that takes id of the unique vertex as a factor and appends it to the array.
  • IF [Conditions] Then [True Execution Code] END IF [False Execution Code] Perform execution code when true or false, depending on the conditions.
  • FOREACH [Execution Code] Performs an execution code with each row as a factor.
  • LOOP [Repeat Execution Code] END LOOP Repeat the execution code in the Loop section until there is no input. 
CREATE FUNCTION ids(vertex[]) RETURNS text[] AS $$ DECLARE v vertex; vids text[]; BEGIN IF $1 IS NULL THEN RETURN ARRAY[]::text[]; END IF; FOREACH v IN ARRAY $1 LOOP vids = array_append(vids, id(v)::text); END LOOP; vids = vids[2:]; RETURN vids; END; $$ LANGUAGE plpgsql;
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Check the Fraud Ring

Explore the raid ring with Cypher Query using Stored Procedure.

SELECT cy.path FROM (match path = (person:person)-[*..]-(person) with path,ids(nodes(path)) as node return path,length(fn_array_uniq(node)) as dcnt, length(node) as cnt) cy WHERE cnt = dcnt
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  • Use the fn_array_uniq function to query the unique Node ID of the Path to be viewed as an array.
  • Use the Ids function to extract only the Node IDs to consider and count and compare them.
  • GraphPath that meets the previous conditions among the Paths inquired in the Match clause is printed and inquired.

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