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https://issues.apache.org/jira/browse/CASSANDRA-13983?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16242533#comment-16242533
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Blake Eggleston commented on CASSANDRA-13983:
---------------------------------------------
First round of comments:
bin/fqltool
* looks like you unnecessarily copied a nodetool compatibility check at the top
of the file
FullQueryLogger
* configure
** first preconditions check uses {{|}}, not {{||}}
** Personally, I try to avoid combining assignments/evaluations like this
{{RollCycles.valueOf(rollCycle = rollCycle.toUpperCase())}}. They're harder to
follow than they need to be. Could we just parse the value at the top of the
method and check that it's not null here?
WeightedQueue
* It doesn't look like we use special Weigher implementations anywhere. I think
this could be slightly simplified if we made the type param {{<T extends
Weighable>}}?
BinLog
* onReleased
** {{bytesInStoreFiles}} is incremented, but doesn't seem to be decremented
after a file is deleted, so once we've recorded more than maxLogSize, we'll
always delete all files
** I think we should be a bit safer with how we access {{bytesInStoreFiles}}.
The calling method in chronicle is synchronized, so this should be safe as is,
but it doesn't look like there are any documented guarantees that this won't
silently change at some point in the future. Maybe we could synchronize the
method, or use an atomic?
Misc: method comment style is a bit inconsistent. Can you use the {{/** */}}
style, not the {{//}} style?
> Support a means of logging all queries as they were invoked
> -----------------------------------------------------------
>
> Key: CASSANDRA-13983
> URL: https://issues.apache.org/jira/browse/CASSANDRA-13983
> Project: Cassandra
> Issue Type: New Feature
> Components: CQL, Observability, Testing, Tools
> Reporter: Ariel Weisberg
> Assignee: Ariel Weisberg
> Fix For: 4.0
>
>
> For correctness testing it's useful to be able to capture production traffic
> so that it can be replayed against both the old and new versions of Cassandra
> while comparing the results.
> Implementing this functionality once inside the database is high performance
> and presents less operational complexity.
> In [this patch|https://github.com/apache/cassandra/pull/169] there is an
> implementation of a full query log that logs uses chronicle-queue (apache
> licensed, the maven artifacts are labeled incorrectly in some cases,
> dependencies are also apache licensed) to implement a rotating log of queries.
> * Single thread asynchronously writes log entries to disk to reduce impact on
> query latency
> * Heap memory usage bounded by a weighted queue with configurable maximum
> weight sitting in front of logging thread
> * If the weighted queue is full producers can be blocked or samples can be
> dropped
> * Disk utilization is bounded by deleting old log segments once a
> configurable size is reached
> * The on disk serialization uses a flexible schema binary format
> (chronicle-wire) making it easy to skip unrecognized fields, add new ones,
> and omit old ones.
> * Can be enabled and configured via JMX, disabled, and reset (delete on disk
> data), logging path is configurable via both JMX and YAML
> * Introduce new {{fqltool}} in /bin that currently implements {{Dump}} which
> can dump in a human readable format full query logs as well as follow active
> full query logs
> Follow up work:
> * Introduce new {{fqltool}} command Replay which can replay N full query logs
> to two different clusters and compare the result and check for
> inconsistencies. <- Actively working on getting this done
> * Log not just queries but their results to facilitate a comparison between
> the original query result and the replayed result. <- Really just don't have
> specific use case at the moment
> * "Consistent" query logging allowing replay to fully replicate the original
> order of execution and completion even in the face of races (including CAS).
> <- This is more speculative
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