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Alex Petrov commented on CASSANDRA-7826:
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I'm doing a small research on what it may take to get this implemented. It's
clear that it'll require new syntax for nested lookups and updates, but I
wanted to address some larger things.
* {{ComplexColumnData}} is a bag of {{Cells}}, although having nested
collections would require {{ComplexColumnData}} to also contain
{{ComplexColumnData}}.
* in most of places, such as {{Operation}}, there's a single-level mapping:
retrieve a {{ColumnDefinition}}, and then build {{CellPath}} directly within
this column
* it might be good to allow nested {{CellPath}} iteration (maybe? making
{{CellPath}} multi-level, and allowing nested access)
* {{Insert}} and {{Update}} operations that don't require nested access (for
example, {{UPDATE %s SET c[0] = [5,6] WHERE a = 1 AND b = 2}} given {{c is
list<list<int>>}} are a much simpler, since they don't require finding a nested
cell, although nested collections are now stored as {{blobs}}, which is a main
"issue" here
* {{Operation}}s such as {{Set|DeleteField|Addition|Subtraction}} would
probably require the biggest changes, aside the mentioned {{Cell}} changes
Please correct me if I'm wrong somewhere.
> support non-frozen, nested collections
> --------------------------------------
>
> Key: CASSANDRA-7826
> URL: https://issues.apache.org/jira/browse/CASSANDRA-7826
> Project: Cassandra
> Issue Type: Improvement
> Components: CQL
> Reporter: Tupshin Harper
> Assignee: Alex Petrov
> Labels: ponies
> Fix For: 3.x
>
>
> The inability to nest collections is one of the bigger data modelling
> limitations we have right now.
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