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https://issues.apache.org/jira/browse/CASSANDRA-2474?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13047241#comment-13047241
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Jonathan Ellis commented on CASSANDRA-2474:
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bq. How about a nested SELECT
That's an interesting idea.
I work best with examples. So let's take my proposal
{noformat}
SELECT x, y FROM foo:bar WHERE parent='columnA'
{noformat}
and try to come up with a nested-select equivalent. IMO the most natural would
be
{noformat}
SELECT x, y
FROM (SELECT * from foo where id='bar')
WHERE parent='columnA'
{noformat}
My problem with this is that the semantics are completely different than what I
would expect from a relational system, and there is no cue telling me to expect
that difference other than if I happen to know "nested-selects magically
trigger transpose." As someone with a fairly long relational background this
would drive me crazy. :)
More practically, I'd like to provide a single syntax for compound columns in
both CQL and HQL (Hive's SQL) on Cassandra. HQL _does_ support "real" nested
selects so trying to figure out when a nested select should transpose vs when
it should not seems like a non-starter to me.
> CQL support for compound columns
> --------------------------------
>
> Key: CASSANDRA-2474
> URL: https://issues.apache.org/jira/browse/CASSANDRA-2474
> Project: Cassandra
> Issue Type: Sub-task
> Components: API, Core
> Reporter: Eric Evans
> Labels: cql
> Fix For: 1.0
>
>
> For the most part, this boils down to supporting the specification of
> compound column names (the CQL syntax is colon-delimted terms), and then
> teaching the decoders (drivers) to create structures from the results.
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