[GitHub] [age] markgomer commented on issue #1239: [Query Plan]Is it possible to see the query plan for CYPHER?

["markgomer (via GitHub)" <gi...@apache.org>]

markgomer commented on issue #1239:
URL: https://github.com/apache/age/issues/1239#issuecomment-1730192767

   Hi @cho2hhun! 
   
   You can put the command EXPLAIN with the cypher queries, but AGE still is PostgreSQL tables arranged as a graph, so it is essentially transforming the Cypher query into an SQL query that operates on PostgreSQL tables:
   
   ```cypher
   test=# SELECT * FROM cypher('agload', 
           $$
                   EXPLAIN MATCH (co:Country {name:"Albania"})-[e]-(ci:City)
                   RETURN co, e, ci
           $$) 
           as (co agtype, e agtype, ci agtype);
                                                      QUERY PLAN                                                    
   -----------------------------------------------------------------------------------------------------------------
    Nested Loop  (cost=0.00..118223792.34 rows=725 width=96)
      Join Filter: (((e.start_id = co.id) AND (e.end_id = ci.id)) OR ((e.end_id = co.id) AND (e.start_id = ci.id)))
      ->  Nested Loop  (cost=0.00..3656.49 rows=72485 width=614)
            ->  Seq Scan on "Country" co  (cost=0.00..3.79 rows=1 width=402)
                  Filter: (properties @> agtype_build_map('name'::text, '"Albania"'::agtype))
            ->  Seq Scan on "City" ci  (cost=0.00..2927.85 rows=72485 width=212)
      ->  Materialize  (cost=0.00..1982.71 rows=72486 width=29)
            ->  Append  (cost=0.00..1620.28 rows=72486 width=29)
                  ->  Seq Scan on _ag_label_edge e_1  (cost=0.00..0.00 rows=1 width=56)
                  ->  Seq Scan on has_city e_2  (cost=0.00..1257.85 rows=72485 width=29)
   (10 rows)
   ```
   
   With EXPLAIN, you can still get insights into the query's cost and how you might optimize it, though.
   
   To see how the Cypher is transformed into SQL, you might want to execute the query with a debugger, like GDB.
   
   
   


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