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https://issues.apache.org/jira/browse/CASSANDRA-19637?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Benjamin Lerer updated CASSANDRA-19637:
---------------------------------------
Description:
Due to the way multicell collections are implemented, it is not possible to
differentiate between {{null}} and empty collections like it is feasible for
single cell (frozen) collections. Therefore an empty multicell collection will
always be treated as {{null}}.
Unfortunately, the way LWT conditions handle that is not consistent with that.
For example for {{colA list<int>}} non null: {code}.. IF colA >= null{code}
will throw an invalid request error whereas {code}..IF colA >= []{code} will
returns {{true}}.
Moreover, if we insert an empty list through:
{code}INSERT INTO mytable (pk, colA) VALUES (1, []);{code}
and use {code}DELETE FROM mytable WHERE pk=1 IF colA >= []{code} the returned
results will be {code}{false, null}{code}. Which can be quite confusing.
The way to fix that behaviour to make it consistent with other operations is to
consider empty multicell collection input as {{null}} and reject the {{null}}
input for non {{=}} and {{!=}} operator.
was:
Due to the way multicell collections are implemented, it is not possible to
differentiate between {{null}} and empty collections like it is feasible for
single cell (frozen) collections. Therefore an empty multicell collection will
always be treated as {{null}}.
Unfortunately, the way LWT conditions handle that is not consistent with that.
For example for {{colA list<int>}} non null: {code}.. IF colA >= null{code}
will throw an invalid request error whereas {code}..IF colA >= []{code} will
returns {{true}}.
Moreover, if we insert an empty list through:
{code}INSERT INTO mytable (pk, colA) VALUES (1, []);{code}
and use {code}DELETE FROM mytable WHERE pk=1 IF colA >= []{code} the returned
results will be {code}{false, null}{code}. Which can be quite confusing.
The way to fix that behaviour to make it consistent with other operations is to
consider empty multicell collection input as {{null}}.
> LWT conditions on MultiCell collections return invalid results
> --------------------------------------------------------------
>
> Key: CASSANDRA-19637
> URL: https://issues.apache.org/jira/browse/CASSANDRA-19637
> Project: Cassandra
> Issue Type: Bug
> Components: CQL/Semantics
> Reporter: Benjamin Lerer
> Priority: Normal
>
> Due to the way multicell collections are implemented, it is not possible to
> differentiate between {{null}} and empty collections like it is feasible for
> single cell (frozen) collections. Therefore an empty multicell collection
> will always be treated as {{null}}.
> Unfortunately, the way LWT conditions handle that is not consistent with that.
> For example for {{colA list<int>}} non null: {code}.. IF colA >= null{code}
> will throw an invalid request error whereas {code}..IF colA >= []{code} will
> returns {{true}}.
> Moreover, if we insert an empty list through:
> {code}INSERT INTO mytable (pk, colA) VALUES (1, []);{code}
> and use {code}DELETE FROM mytable WHERE pk=1 IF colA >= []{code} the returned
> results will be {code}{false, null}{code}. Which can be quite confusing.
> The way to fix that behaviour to make it consistent with other operations is
> to consider empty multicell collection input as {{null}} and reject the
> {{null}} input for non {{=}} and {{!=}} operator.
>
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