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Date: Tue, 13 Jul 2010 16:20:51 -0400 (EDT)
From: "Toby Jungen (JIRA)" <jira@apache.org>
To: commits@cassandra.apache.org
Subject: [jira] Commented: (CASSANDRA-1093) BinaryMemtable interface
 silently dropping data.
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    [ https://issues.apache.org/jira/browse/CASSANDRA-1093?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12887980#action_12887980 ] 

Toby Jungen commented on CASSANDRA-1093:
----------------------------------------

Thanks for the insight Jonathan. That was my intuition as well, and I observed my cluster periodically marking nodes as down for a second or two. I figured it was random network hiccups, since our network hardware is rather old. It would make sense that these periodic interruptions caused the BMT to lose data.

While looking through the code, I did try to see if I could use BMT with the blocking MessagingService API (in the way the Thrift API works unless ConsistencyLevel.ZERO is specified), but it looks like BMT is hardcoded to be asynchronous. It might be nice for that option to be there, but since this issue appears to only affect me (and I no longer need to use BMT for my purposes), it's a super-low priority suggestion.

> BinaryMemtable interface silently dropping data.
> ------------------------------------------------
>
>                 Key: CASSANDRA-1093
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-1093
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Core
>         Environment: Linux Centos5, Fedora Core 4. Java HotSpot Server 1.6.0_14. See readme for more details.
>            Reporter: Toby Jungen
>            Assignee: Brandon Williams
>             Fix For: 0.6.3
>
>         Attachments: cassandra_bmt_test.tar.gz
>
>
> I've been attempting to use the Binary Memtable (BMT) interface to load a large number of rows. During my testing, I discovered that on larger loads (~1 million rows), occasionally some of the data never appears in the database. This happens in a non-deterministic manner, as sometimes all the data loads fine, and other times a significant chunk goes missing. No errors are ever logged to indicate a problem. I'm attaching some sample code that approximates my application's usage of Cassandra and explains this bug in more detail.

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