cassandra-commits mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Sylvain Lebresne (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-4986) Allow finer control of ALLOW FILTERING behavior
Date Mon, 08 Dec 2014 10:04:12 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-4986?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14237701#comment-14237701
] 

Sylvain Lebresne commented on CASSANDRA-4986:
---------------------------------------------

[~michalm] is correct, but let me add on top of that that this ticket was open a long time
ago and there hasn't been any conscensus on it's usefulness. In fact, I'm myself now not entirely
convinced that we need that kind of complexity. What could maybe make sense instead is a simple
"filtering warn threshold" the same way we have {{tombstone_warn_threshold}}.

> Allow finer control of ALLOW FILTERING behavior
> -----------------------------------------------
>
>                 Key: CASSANDRA-4986
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-4986
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: Sylvain Lebresne
>            Priority: Minor
>             Fix For: 3.0
>
>
> CASSANDRA-4915 added {{ALLOW FILTERING}} to warn people when they do potentially inefficient
queries. However, as discussed in the former issue it would be interesting to allow controlling
that mode more precisely by allowing something like:
> {noformat}
> ... ALLOW FILTERING MAX 500
> {noformat}
> whose behavior would be that the query would be short-circuited if it filters (i.e. read
but discard from the ResultSet) more than 500 CQL3 rows.
> There is however 2 details I'm not totally clear on:
> # what to do exactly when we reach the max filtering allowed. Do we return what we have
so far, but then we need to have a way to say in the result set that the query was short-circuited.
Or do we just throw an exception TooManyFiltered (simpler but maybe a little bit less useful).
> # what about deleted records? Should we count them as 'filtered'? Imho the logical thing
is to not count them as filtered, since after all we "filter them out" in the normal path
(i.e. even when ALLOW FILTERING is not used).



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)

Mime
View raw message