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https://issues.apache.org/jira/browse/CASSANDRA-3647?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13292775#comment-13292775
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Sylvain Lebresne commented on CASSANDRA-3647:
---------------------------------------------
Pushed at https://github.com/pcmanus/cassandra/commits/3647 patches for this.
This pretty much implement the syntax of Jonathan's comment above, except that
literals must not be quoted. Supported methods are:
* maps: put and discard.
* sets: add, add_all (takes n arguments) and discard.
* lits: append, append_all, prepend, prepend_all, set (to set the value at a
specific index), discard (discard an object given its value) and discard_idx
(discard given the index).
The implementation for maps and set is rather straighforward. Lists are
implemented as a map of TimeUUID -> value. Prepend is supported by the trick
described in the previous comments of picking a reference time (1 january 2010
as it turns out) and using that reference minus now as a timestamp. The list
method set, discard and discard_idx share in common that they do a
read-before-write (we read the whole list to find the TimeUUID corresponding to
the element to update; we then write that element (I don't think we need to
overwrite the entire list at all)).
Another detail worth mentioning is literals. When setting a literal we must
erase the previous list. To do so, the implementation insert a (range)
tombstone at 'timestamp - 1'. This have the unfortunate consequence that if you
do 2 update with a literal in the same millisecond, you won't end up with one
or the other, but rather as a merge of both literals. I don't see a good way
how to do otherwise.
As of these patches, collections (lists/maps/sets) are limited to table
definition that use a composed PRIMARY KEY. The reason is that otherwise the
underlying comparator is not a composite one, and thus there is no way to
support the collection. I very strongly think that we should change this
behavior and I've opened CASSANDRA-4329 for that. But besides this limitation,
these patches are ready for review and I've pushed a few tests those in dtests
(in cql_tests.py).
> 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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