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Posted to commits@cassandra.apache.org by "Sylvain Lebresne (Created) (JIRA)" <ji...@apache.org> on 2012/02/20 19:45:34 UTC
[jira] [Created] (CASSANDRA-3934) Short read protection is broken
Short read protection is broken
-------------------------------
Key: CASSANDRA-3934
URL: https://issues.apache.org/jira/browse/CASSANDRA-3934
Project: Cassandra
Issue Type: Bug
Affects Versions: 1.0.2
Reporter: Sylvain Lebresne
Assignee: Sylvain Lebresne
Priority: Minor
Fix For: 1.0.8, 1.1.0
When a read needs to do more than one retry (due to short reads), the originalCount is not preserved by the retry leading to returning more than the requested number of columns.
Moreover, when a retried read checks whether more retry is needed, it doesn't compare the number of live column retrieved against the original number of columns requested by the user, but against the number of columns requested during the retry, making it much more likely to actually do one more retry.
This catch by the two tests 'short_read_test' and 'short_read_reversed_test' at https://github.com/riptano/cassandra-dtest/blob/master/consistency_test.py that are failing intermittently.
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[jira] [Commented] (CASSANDRA-3934) Short read protection is broken
Posted by "Brandon Williams (Commented) (JIRA)" <ji...@apache.org>.
[ https://issues.apache.org/jira/browse/CASSANDRA-3934?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13213538#comment-13213538 ]
Brandon Williams commented on CASSANDRA-3934:
---------------------------------------------
+1
> Short read protection is broken
> -------------------------------
>
> Key: CASSANDRA-3934
> URL: https://issues.apache.org/jira/browse/CASSANDRA-3934
> Project: Cassandra
> Issue Type: Bug
> Affects Versions: 1.0.2
> Reporter: Sylvain Lebresne
> Assignee: Sylvain Lebresne
> Priority: Minor
> Fix For: 1.0.8, 1.1.0
>
> Attachments: 3934.txt
>
>
> When a read needs to do more than one retry (due to short reads), the originalCount is not preserved by the retry leading to returning more than the requested number of columns.
> Moreover, when a retried read checks whether more retry is needed, it doesn't compare the number of live column retrieved against the original number of columns requested by the user, but against the number of columns requested during the retry, making it much more likely to actually do one more retry.
> This catch by the two tests 'short_read_test' and 'short_read_reversed_test' at https://github.com/riptano/cassandra-dtest/blob/master/consistency_test.py that are failing intermittently.
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[jira] [Updated] (CASSANDRA-3934) Short read protection is broken
Posted by "Sylvain Lebresne (Updated) (JIRA)" <ji...@apache.org>.
[ https://issues.apache.org/jira/browse/CASSANDRA-3934?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Sylvain Lebresne updated CASSANDRA-3934:
----------------------------------------
Attachment: 3934.txt
Patch is against 1.0. The patch:
* don't retry if we have enough columns to satisfy the initial query
* keep the original count intact even if we do multiple retries.
* optimize the number of columns asked by a retry based on the ratio of number of column got/total asked on the initial query.
> Short read protection is broken
> -------------------------------
>
> Key: CASSANDRA-3934
> URL: https://issues.apache.org/jira/browse/CASSANDRA-3934
> Project: Cassandra
> Issue Type: Bug
> Affects Versions: 1.0.2
> Reporter: Sylvain Lebresne
> Assignee: Sylvain Lebresne
> Priority: Minor
> Fix For: 1.0.8, 1.1.0
>
> Attachments: 3934.txt
>
>
> When a read needs to do more than one retry (due to short reads), the originalCount is not preserved by the retry leading to returning more than the requested number of columns.
> Moreover, when a retried read checks whether more retry is needed, it doesn't compare the number of live column retrieved against the original number of columns requested by the user, but against the number of columns requested during the retry, making it much more likely to actually do one more retry.
> This catch by the two tests 'short_read_test' and 'short_read_reversed_test' at https://github.com/riptano/cassandra-dtest/blob/master/consistency_test.py that are failing intermittently.
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