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Yifan Cai commented on CASSANDRA-17425:
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I do not have objections on extending 'writetime' and 'tty' functions to
support multi-cell types, although I do doubt how practical it is to return the
timestamps/TTLs of the entire collection.
As said, the new function proposed is _different_ from 'writetime'. The goal is
to allow end-user to quickly tell the latest modification time of a column,
regardless of a single-cell or multi-cell.
Implementation-wise, I could just modify the 'WritetimeOrTTLSelector' to
implement. But a new implementation is add instead, since I think we will be
benefit from separating out the responsibility from the perspective of
maintenance.
On the other hand, Cassandra has function variants. For example, 'timeuuid' and
its variants, ['minTimeuuid' and 'maxTimeuuid'
|https://cassandra.apache.org/doc/trunk/cassandra/cql/cql_singlefile.html#mintimeuuid-and-maxtimeuuid].
bq. I would prefer to wait a bit for it because I have some significant changes
coming in this area for CASSANDRA-11871.
Do you have an ETA on when your patch will land? This patch is relatively
simple and isolated. Even if we merge it ahead, I guess it should not be a
troublesome conflict. Maybe I was wrong?
At the end, appreciate all discussions.
> Add new CQL function maxWritetime
> ---------------------------------
>
> Key: CASSANDRA-17425
> URL: https://issues.apache.org/jira/browse/CASSANDRA-17425
> Project: Cassandra
> Issue Type: Improvement
> Components: CQL/Syntax
> Reporter: Yifan Cai
> Assignee: Yifan Cai
> Priority: Normal
>
> The function "writetime" does not support multi-cell types, e.g. collections
> and UDT. It would be useful to enable querying the latest modified timestamp
> of a column value.
> I'd like to propose to add a new function named "maxWritetime", which returns
> the largest timestamp amongst the cells. When being applied to the single
> cell types, it returns the same result as "writetime".
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