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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