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https://issues.apache.org/jira/browse/CASSANDRA-18078?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17856538#comment-17856538
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Stefan Miklosovic commented on CASSANDRA-18078:
-----------------------------------------------
[~mck]
I don't have any problem with delivering this (removing it from 5.0).
What we should do about the "add-on" which introduces the application of
collection functions to a non-collection type? That is strictly speaking a new
feature and should go probably just to trunk.
> Consider removing MAXWRITETIME function
> ---------------------------------------
>
> Key: CASSANDRA-18078
> URL: https://issues.apache.org/jira/browse/CASSANDRA-18078
> Project: Cassandra
> Issue Type: Improvement
> Components: CQL/Syntax
> Reporter: Andres de la Peña
> Assignee: Stefan Miklosovic
> Priority: Normal
> Fix For: 5.0.x
>
> Time Spent: 50m
> Remaining Estimate: 0h
>
> CASSANDRA-17425 added a new {{MAXWRITETIME}} function that allows to retrieve
> the maximum timestamp of a multi-cell column. For example:
> {code:java}
> > CREATE TABLE t (k int PRIMARY KEY, v set<int>);
> > INSERT INTO t (k, v) VALUES (1, {1, 2}) USING TIMESTAMP 100;
> > UPDATE t USING TIMESTAMP 200 SET v += {3} WHERE k=1;
> > SELECT maxwritetime(v) FROM t;
> maxwritetime(v)
> -----------------
> 200
> {code}
> Later, CASSANDRA-8877 added the means to retrieve the write times and TTLs of
> each of the cells in a multi-cell column:
> {code:java}
> > SELECT writetime(v) FROM t;
> writetime(v)
> -----------------
> [100, 100, 200]
> > SELECT writetime(v[1]) FROM t;
> writetime(v[1])
> -----------------
> 100
> {code}
> Quite recently, CASSANDRA-18060 has added generic CQL functions to get the
> min and max items in a collection. Those functions can be used in combination
> with the classic {{writetime}} function to get the same results as the new
> {{maxwritetime}} function:
> {code:java}
> > SELECT collection_max(writetime(v)) FROM t;
> system.collection_max(writetime(v))
> -------------------------------------
> 200
> {code}
> Those new functions can also be used to get the min timestamp, or the min/max
> TTL, for which there isn't a specific function:
> {code:java}
> SELECT collection_min(writetime(v)) FROM t;
> SELECT collection_max(writetime(v)) FROM t;
> SELECT collection_avg(writetime(v)) FROM t;
> SELECT collection_min(ttl(v)) FROM t;
> SELECT collection_max(ttl(v)) FROM t;
> SELECT collection_avg(ttl(v)) FROM t;
> {code}
> I think this makes the new {{maxwritetime}} mostly redundant, since the new
> functions can achieve the same results in a more generic way. Since the new
> {{maxwritetime}} function is only on trunk, we should consider whether we
> want to remove it in favour of the generic functions.
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