Mailing-List: contact commits-help@cassandra.apache.org; run by ezmlm
Precedence: bulk
Reply-To: dev@cassandra.apache.org
Date: Mon, 6 Mar 2017 15:49:32 +0000 (UTC)
From: "Alex Petrov (JIRA)" <jira@apache.org>
To: commits@cassandra.apache.org
Message-ID: <JIRA.13021068.1479282633000.7965.1488815372859@Atlassian.JIRA>
In-Reply-To: <JIRA.13021068.1479282633000@Atlassian.JIRA>
References: <JIRA.13021068.1479282633000@Atlassian.JIRA> <JIRA.13021068.1479282633082@jira-lw-us.apache.org>
Subject: [jira] [Commented] (CASSANDRA-12915) SASI: Index intersection with
 an empty range really inefficient
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit
archived-at: Mon, 06 Mar 2017 15:49:41 -0000


    [ https://issues.apache.org/jira/browse/CASSANDRA-12915?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15897529#comment-15897529 ] 

Alex Petrov commented on CASSANDRA-12915:
-----------------------------------------

I've poked around a bit and could not see any behaviour change if we only introduce an empty iterator, like [here|https://github.com/ifesdjeen/cassandra/commit/78b1ff630536b0f48787ced74a66d702d13637ba] (this is by no means meant as a final version of the patch, only bringing it here as an example and a base for discussion). I'm just trying to understand the purpose of the rest of changes, it'd be good to hear your opinion.

> SASI: Index intersection with an empty range really inefficient
> ---------------------------------------------------------------
>
>                 Key: CASSANDRA-12915
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-12915
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: sasi
>            Reporter: Corentin Chary
>            Assignee: Corentin Chary
>             Fix For: 3.11.x, 4.x
>
>
> It looks like RangeIntersectionIterator.java and be pretty inefficient in some cases. Let's take the following query:
> SELECT data FROM table WHERE index1 = 'foo' AND index2 = 'bar';
> In this case:
> * index1 = 'foo' will match 2 items
> * index2 = 'bar' will match ~300k items
> On my setup, the query will take ~1 sec, most of the time being spent in disk.TokenTree.getTokenAt().
> if I patch RangeIntersectionIterator so that it doesn't try to do the intersection (and effectively only use 'index1') the query will run in a few tenth of milliseconds.
> I see multiple solutions for that:
> * Add a static thresold to avoid the use of the index for the intersection when we know it will be slow. Probably when the range size factor is very small and the range size is big.
> * CASSANDRA-10765


--
This message was sent by Atlassian JIRA
(v6.3.15#6346)