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https://issues.apache.org/jira/browse/QPID-8592?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Tomas Vavricka closed QPID-8592.
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> [Broker-J] Pass context value from parent query into the subquery
> -----------------------------------------------------------------
>
> Key: QPID-8592
> URL: https://issues.apache.org/jira/browse/QPID-8592
> Project: Qpid
> Issue Type: Improvement
> Components: Broker-J
> Affects Versions: qpid-java-broker-8.0.6
> Reporter: Daniil Kirilyuk
> Priority: Minor
> Fix For: qpid-java-broker-9.0.0
>
>
> Current version of broker query engine doesn't support subqueries referencing
> fields from the parent query. To support this possibility it's needed to pass
> the context from parent query to the subquery.
> To pass context from parent query to the subquery it's needed to add current
> stream item and it's alias to the Evaluation context. It can be done using
> Stream#peek() inside of SelectEvaluator#evaluate().
> As the aliases from parent query will affect subquery sorting, it also will
> be required to consider added aliases in QueryEvaluator#createComparator().
> This should allow to use values from parent queries in subqueries, e.g.:
> {code:java}
> SELECT
> id,
> name,
> (SELECT name FROM connection WHERE SUBSTRING(name, 1, POSITION(']' IN name))
> = '[' + SUBSTRING(c.name, 1, POSITION('|' IN c.name) - 1) + ']') as
> connection,
> (SELECT id FROM connection WHERE SUBSTRING(name, 1, POSITION(']' IN name)) =
> '[' + SUBSTRING(c.name, 1, POSITION('|' IN c.name) - 1) + ']') as
> connectionId,
> (SELECT name FROM session WHERE id = c.session.id) as session
> FROM consumer c{code}
> or
> {code:java}
> SELECT
> name,
> destination,
> (SELECT id FROM queue WHERE name = b.destination) AS destinationId,
> exchange,
> (SELECT id FROM exchange WHERE name = b.exchange) AS exchangeId
> FROM binding b
> WHERE name = 'broadcast.amqp_user1.xxx.#'{code}
> or
> {code:java}
> SELECT
> alias,
> (SELECT COUNT(id) FROM queue WHERE POSITION(UPPER(c.alias) IN name) > 0) AS
> queueCount
> FROM certificate c{code}
> This would allow to retrieve values from associated entities without firing
> additional queries.
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