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From "Sylvain Lebresne (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-3647) Support set and map value types in CQL
Date Tue, 12 Jun 2012 08:07:43 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-3647?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13293431#comment-13293431
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Sylvain Lebresne commented on CASSANDRA-3647:
---------------------------------------------

bq. If we combined this with the [] syntax for setting a single item, that would just leave
us with discard to solve and we wouldn't need this somewhat clunky "method call" syntax.

That's definitively an option. One drawback I can think of is that I don't see how to support
both the {{discard}} and {{discard_idx}} methods for lists (at least for {{list<int>}}),
while the clunkier "method call" syntax has no problem with that. I would almost agree that
we could offer only {{discard_idx}} with no special syntax for {{discard}}, if it wasn't for
the fact that users can't implement {{discard}} as well as we can (because even if they do
a read, they won't have access to the underlying TimeUUID, and thus would risk to remove the
wrong element if there is concurrent update/delete).

{quote}
Maybe some extension to DELETE?
{noformat}
DELETE L[0] FROM foo WHERE ...
DELETE M['asdf'] FROM foo WHERE ...
DELETE S[4] FROM foo WHERE ...
{noformat}
{quote}

I'm not sure I'm convinced by that syntax for sets, as this reuse a very standard notation
for something not standard at all (and I know I suggested a similar for slice for sets above,
but upon further reflexion I don't like it). It's also related to the {{discard/discard_idx}}
problem above since if we find a "better" syntax for sets, we can reuse it for the discard
of lists. That being said, I don't have a clearly perfect idea. One suggestion would be to
use brackets instead of square brackets, just to make it clear that it selects a value (so
DELETE S{4} FROM ...).

bq. That's pretty tough to explain without leaking implementation details

I absolutely agree and I'm certainly not saying it's not a problem. It's just that I don't
have a solution to that problem, outside of removing the possibility to "set" a literal at
all (which maybe is the right solution).

                
> Support set and map value types in CQL
> --------------------------------------
>
>                 Key: CASSANDRA-3647
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-3647
>             Project: Cassandra
>          Issue Type: New Feature
>          Components: API, Core
>            Reporter: Jonathan Ellis
>            Assignee: Sylvain Lebresne
>              Labels: cql
>             Fix For: 1.2
>
>
> Composite columns introduce the ability to have arbitrarily nested data in a Cassandra
row.  We should expose this through CQL.

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