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Date: Wed, 29 Jun 2016 00:38:10 +0000 (UTC)
From: "Sharvanath Pathak (JIRA)" <jira@apache.org>
To: commits@cassandra.apache.org
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Subject: [jira] [Updated] (CASSANDRA-12107) Fix range scans for table with
 live static rows
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archived-at: Wed, 29 Jun 2016 00:38:12 -0000


     [ https://issues.apache.org/jira/browse/CASSANDRA-12107?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Sharvanath Pathak updated CASSANDRA-12107:
------------------------------------------
    Description: 
We were seeing some weird behaviour with limit based scan queries. In particular, we see the following:
{noformat}
$ cqlsh -k sd -e "consistency local_quorum; SELECT uuid, token(uuid) FROM files WHERE token(uuid) >= token('6b470c3e43ee06d1') limit 2"
Consistency level set to LOCAL_QUORUM.

 uuid             | system.token(uuid)
------------------+----------------------
 6b470c3e43ee06d1 | -9218823070349964862
 484b091ca97803cd | -8954822859271125729

(2 rows)
$ cqlsh -k sd -e "consistency local_quorum; SELECT uuid, token(uuid) FROM files WHERE token(uuid) > token('6b470c3e43ee06d1') limit 1"
Consistency level set to LOCAL_QUORUM.

 uuid             | system.token(uuid)
------------------+----------------------
 c348aaec2f1e4b85 | -9218781105444826588
{noformat}
In the table uuid is partition key, and it has a clustering key as well.
So the uuid "c348aaec2f1e4b85" should be the second one in the limit query. After some investigation, it seems to me like the issue is in the way DataLimits handles static rows. Here is a patch for trunk (https://github.com/sharvanath/cassandra/commit/9a460d40e55bd7e3604d987ed4df5c8c2e03ffdc) which seems to fix it for me. Please take a look, seems like a pretty critical issue to me.

I have forked the dtests for it as well. However, since trunk has some failures already, I'm not fully sure how to infer the results.
http://cassci.datastax.com/view/Dev/view/sharvanath/job/sharvanath-fixScan-dtest/
http://cassci.datastax.com/view/Dev/view/sharvanath/job/sharvanath-fixScan-testall/

  was:
We were seeing some weird behaviour with limit based scan queries. In particular, we see the following:
{noformat}
$ cqlsh -k sd -e "consistency local_quorum; SELECT uuid, token(uuid) FROM files WHERE token(uuid) >= token('6b470c3e43ee06d1') limit 2"
Consistency level set to LOCAL_QUORUM.

 uuid             | system.token(uuid)
------------------+----------------------
 6b470c3e43ee06d1 | -9218823070349964862
 484b091ca97803cd | -8954822859271125729

(2 rows)
$ cqlsh -k sd -e "consistency local_quorum; SELECT uuid, token(uuid) FROM files WHERE token(uuid) > token('6b470c3e43ee06d1') limit 1"
Consistency level set to LOCAL_QUORUM.

 uuid             | system.token(uuid)
------------------+----------------------
 c348aaec2f1e4b85 | -9218781105444826588
{noformat}
In the table uuid is partition key, and it has a clustering key as well.
So the uuid "c348aaec2f1e4b85" should be the second one in the limit query. After some investigation, it seems to me like the issue is in the way DataLimits handles static rows. Here is a patch (https://github.com/sharvanath/cassandra/commit/9a460d40e55bd7e3604d987ed4df5c8c2e03ffdc) which seems to fix it for me. Please take a look, seems like a pretty critical issue to me.

I have forked the dtests for it as well, but since trunk has some failure I'm not fully sure how to infer the results.
http://cassci.datastax.com/view/Dev/view/sharvanath/job/sharvanath-fixScan-dtest/
http://cassci.datastax.com/view/Dev/view/sharvanath/job/sharvanath-fixScan-testall/


> Fix range scans for table with live static rows
> -----------------------------------------------
>
>                 Key: CASSANDRA-12107
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-12107
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Core
>            Reporter: Sharvanath Pathak
>             Fix For: 3.0.8
>
>
> We were seeing some weird behaviour with limit based scan queries. In particular, we see the following:
> {noformat}
> $ cqlsh -k sd -e "consistency local_quorum; SELECT uuid, token(uuid) FROM files WHERE token(uuid) >= token('6b470c3e43ee06d1') limit 2"
> Consistency level set to LOCAL_QUORUM.
>  uuid             | system.token(uuid)
> ------------------+----------------------
>  6b470c3e43ee06d1 | -9218823070349964862
>  484b091ca97803cd | -8954822859271125729
> (2 rows)
> $ cqlsh -k sd -e "consistency local_quorum; SELECT uuid, token(uuid) FROM files WHERE token(uuid) > token('6b470c3e43ee06d1') limit 1"
> Consistency level set to LOCAL_QUORUM.
>  uuid             | system.token(uuid)
> ------------------+----------------------
>  c348aaec2f1e4b85 | -9218781105444826588
> {noformat}
> In the table uuid is partition key, and it has a clustering key as well.
> So the uuid "c348aaec2f1e4b85" should be the second one in the limit query. After some investigation, it seems to me like the issue is in the way DataLimits handles static rows. Here is a patch for trunk (https://github.com/sharvanath/cassandra/commit/9a460d40e55bd7e3604d987ed4df5c8c2e03ffdc) which seems to fix it for me. Please take a look, seems like a pretty critical issue to me.
> I have forked the dtests for it as well. However, since trunk has some failures already, I'm not fully sure how to infer the results.
> http://cassci.datastax.com/view/Dev/view/sharvanath/job/sharvanath-fixScan-dtest/
> http://cassci.datastax.com/view/Dev/view/sharvanath/job/sharvanath-fixScan-testall/


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