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https://issues.apache.org/jira/browse/CASSANDRA-13632?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16163650#comment-16163650
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Jason Brown commented on CASSANDRA-13632:
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[~whangsf] Can you provide steps to reproduce? Also, what kind of improvement
did you see when you applied your patch? Specific numbers would be great!
wrt to thrift, are you using CQL over thrift, or old-school thrift a la
astyanx/hector/pycassa? I tried to dig up a thrift client but it was pretty
painful and I stopped.
> Digest mismatch if row is empty
> -------------------------------
>
> Key: CASSANDRA-13632
> URL: https://issues.apache.org/jira/browse/CASSANDRA-13632
> Project: Cassandra
> Issue Type: Bug
> Components: Local Write-Read Paths
> Reporter: Andrew Whang
> Assignee: Andrew Whang
> Fix For: 3.0.x
>
>
> This issue is similar to CASSANDRA-12090. Quorum read queries that include a
> column selector (non-wildcard) result in digest mismatch when the row is
> empty (key does not exist). It seems the data serialization path checks if
> rowIterator.isEmpty() and if so ignores column names (by setting IS_EMPTY
> flag). However, the digest serialization path does not perform this check and
> includes column names. The digest comparison results in a mismatch. The
> mismatch does not end up issuing a read repair mutation since the underlying
> data is the same.
> The mismatch on the read path ends up doubling our p99 read latency. We
> discovered this issue while testing a 2.2.5 to 3.0.13 upgrade.
> One thing to note is that we're using thrift, which ends up handling the
> ColumnFilter differently than the CQL path.
> As with CASSANDRA-12090, fixing the digest seems sensible.
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