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https://issues.apache.org/jira/browse/CASSANDRA-9229?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14519094#comment-14519094
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Benjamin Lerer commented on CASSANDRA-9229:
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While going back to my patch, I realized that I missunderstood the way the
{{{TimeType}} was working and that by consequence my patch was wrong.
The {{TimeType}} represents "the number of nanoseconds since midnight". The
problem being that the notion of midnight is relative to a Timezone.
For the {{TimestampType}} or {{DateType}} the value is always stored internally
in UTC but the way it is output is not clearly defined. By consequence, when
converting from a {{UUIDTimestampType}} to a {{TimeType}} we have 2 choices:
# use midnight in the server timezone, if we assume that the uuitimestamp was
generated using {{now()}}
# do not provide that type of function
The same question occurs if we want to convert a {{TimestampType}} into a
{{TimeType}}.
> Add functions to convert timeuuid to date or time
> -------------------------------------------------
>
> Key: CASSANDRA-9229
> URL: https://issues.apache.org/jira/browse/CASSANDRA-9229
> Project: Cassandra
> Issue Type: New Feature
> Reporter: Michaël Figuière
> Assignee: Benjamin Lerer
> Labels: cql, doc-impacting
> Fix For: 3.0
>
> Attachments: CASSANDRA-9229.txt
>
>
> As CASSANDRA-7523 brings the {{date}} and {{time}} native types to Cassandra,
> it would be useful to add builtin function to convert {{timeuuid}} to these
> two new types, just like {{dateOf()}} is doing for timestamps.
> {{timeOf()}} would extract the time component from a {{timeuuid}}. Example
> use case could be at insert time with for instance {{timeOf(now())}}, as well
> as at read time to compare the time component of a {{timeuuid}} column in a
> {{WHERE}} clause.
> The use cases would be similar for {{date}} but the solution is slightly less
> obvious, as in a perfect world we would want {{dateOf()}} to convert to
> {{date}} and {{timestampOf()}} for {{timestamp}}, unfortunately {{dateOf()}}
> already exist and convert to a {{timestamp}}, not a {{date}}. Making this
> change would break many existing CQL queries which is not acceptable.
> Therefore we could use a different name formatting logic such as {{toDate}}
> or {{dateFrom}}. We could then also consider using this new name convention
> for the 3 dates related types and just have {{dateOf}} becoming a deprecated
> alias.
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