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https://issues.apache.org/jira/browse/CASSANDRA-17762?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17607367#comment-17607367
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Ekaterina Dimitrova commented on CASSANDRA-17762:
-------------------------------------------------
I'll be looking into this one soon.
Reading here, it seems more or less there is some consensus but I guess I still
need to send mail to the ML at least for awareness?
To summarize:
_Utilizing {{IS NULL}} and {{IS NOT NULL in LWT}} (in practice we need to do it
everywhere including for column filtering (CASSANDRA-10715))._
_Even without looking at SQL we are also not consistent within CQL where we use
x {{= null}} and x != null for LWT but {{IS NOT NULL}} for Materialized views._
_On one side to be consistent in CQL, on another consistent with SQL._
_It should also be easy to support both syntaxes ({{{}x = null{}}}/{{{}X IS
NULL{}}}) while warning the user that the first syntax is deprecated until the
next major release._
I guess the question is [~avi.kivity]'s point around NULL being valid in SQL.
Shall we deal with the change of meaning for X = NULL as part of this ticket or
just deprecate for now X = NULL and spin that part into another ticket? And
still bring that to the mailing list...
There were a few discussions in parallel around CQL syntax lately so I hope I
didn't miss any point here.
> LWT IF col = NULL is inconsistent with SQL NULL
> -----------------------------------------------
>
> Key: CASSANDRA-17762
> URL: https://issues.apache.org/jira/browse/CASSANDRA-17762
> Project: Cassandra
> Issue Type: Bug
> Components: CQL/Semantics
> Reporter: Avi Kivity
> Assignee: Ekaterina Dimitrova
> Priority: Normal
> Fix For: 4.x
>
>
> In SQL, any comparison with NULL is NULL, which is interpreted as FALSE in a
> condition. To test for NULLness, you use IS NULL or IS NOT NULL.
> But LWT uses IF col = NULL as a NULLness test. This is likely to confuse
> people coming from SQL and hamper attempts to extend the dialect.
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