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Posted to commits@cassandra.apache.org by "Andres de la Peña (Jira)" <ji...@apache.org> on 2022/12/02 12:26:00 UTC
[jira] [Commented] (CASSANDRA-18085) Add support for singletons on CQL collection functions
[ https://issues.apache.org/jira/browse/CASSANDRA-18085?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17642474#comment-17642474 ]
Andres de la Peña commented on CASSANDRA-18085:
-----------------------------------------------
Here is the PR modifying the collection functions to support not-collection arguments:
||PR||CI||
|[trunk|https://github.com/apache/cassandra/pull/2037]|[j8|https://app.circleci.com/pipelines/github/adelapena/cassandra/2524/workflows/5979d976-7a01-4afa-ae2a-b66f7810334f] [j11|https://app.circleci.com/pipelines/github/adelapena/cassandra/2524/workflows/8989fb9c-f683-4a3c-b906-abe824922b72]|
CC [~yifanc] [~frankgh] [~blerer]
> Add support for singletons on CQL collection functions
> ------------------------------------------------------
>
> Key: CASSANDRA-18085
> URL: https://issues.apache.org/jira/browse/CASSANDRA-18085
> Project: Cassandra
> Issue Type: Improvement
> Components: CQL/Semantics
> Reporter: Andres de la Peña
> Assignee: Andres de la Peña
> Priority: Normal
> Fix For: 4.x
>
> Time Spent: 10m
> Remaining Estimate: 0h
>
> CASSANDRA-18060 has added generic CQL functions to get the min, max, sum, avg and number of items in a collection. These functions can only be applied to collection values. The functions throw an {{InvalidRequestEception}} when applied to not-collection values.
> CASSANDRA-18078 has been pointed out that those functions could be applied also to not-collection values, considering that the not-collection argument can be considered a collection of a single element. For example:
> * collection_min(7) = collection_min([7]) = collection_min(\{7}) = 7
> * collection_max(7) = collection_max([7]) = collection_max(\{7}) = 7
> * collection_sum(7) = collection_sum([7]) = collection_sum(\{7}) = 7
> * collection_avg(7) = collection_avg([7]) = collection_avg(\{7}) = 7
> * collection_count(7) = collection_count([7]) = collection_count(\{7}) = 1
> This would be particularly useful when used in combination with functions such as {{writetime}} and {{{}ttl{}}}. Those functions can return either single values or collections of values depending on whether the column passed as argument is multicell. Thus, users interested on getting the min/max/sum/avg of the writetimes/ttls of a column need to consider the type of the column when choosing what functions they should use. With the proposed change they could just use, for example, {{collection_max(writetime(column))}} regardless of the column type.
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