How to set many-to-many relationship in elasticsearch, logstash - mysql

Question

I'm trying to set up a many-to-many relationship using elasticSearch.
I searched and found that there is no way to set it up like a relational database.
So I want to set it like parent-children.
How should I write the statement in the code below?
#logstash.conf
jdbc{
jdbc_driver_library => "/Users/kun/Downloads/mysql-connector-java-8.0.29/mysql-connector-java-8.0.29.jar"
jdbc_driver_class => "com.mysql.jdbc.Driver"
jdbc_connection_string => "jdbc:mysql://127.0.0.1:3306/dbtest"
jdbc_user => "xxxx"
jdbc_password => "xxxx"
tracking_column => "unix_ts_in_secs_user"
use_column_value => true
tracking_column_type => "numeric"
schedule => "*/3 * * * * *"
statement => "SELECT *,UNIX_TIMESTAMP(updatedAt) as unix_ts_in_secs_user,
(select
JSON_ARRAYAGG(
JSON_OBJECT(
'id', `id`,
'name', `name`,
'name2', `name2`
)
)
from cat inner join user_cats_cat on user_cats_cat.catId = cat.id and user_cats_cat.userId = user.id) as cat
FROM user WHERE (UNIX_TIMESTAMP(updatedAt) > :sql_last_value AND updatedAt < NOW())"
last_run_metadata_path => "./logstash_jdbc_last_run_user"
type => "user"
}
If you write the code as above, I could not call cat.name in elasticSearch.
GET index_user_test/_search
{
"track_total_hits": true,
"from":0,
"size":10,
"query" : {
"bool" : {
"must" : [
{
"query_string":{
"fields": ["name.ngram","name2.ngram"],
"query": "kun"
}
},
{
"terms" : {
"cat.name" : "blue"
}
}
]
}
}
}
cat and user a many-to-many relationship.
user_cats_cat is an intermediate table between user and cat.
Thank you!