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https://issues.apache.org/jira/browse/HBASE-7774?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13572141#comment-13572141
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ramkrishna.s.vasudevan commented on HBASE-7774:
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bq.I think this is fixed in some other Jira.
Yes. This is fixed. I remember it was an issue raised by Lars George.
> RegionObserver.prePut() cannot rely on the Put's timestamps, can even cause
> data loss
> -------------------------------------------------------------------------------------
>
> Key: HBASE-7774
> URL: https://issues.apache.org/jira/browse/HBASE-7774
> Project: HBase
> Issue Type: Bug
> Affects Versions: 0.92.2, 0.96.0, 0.94.4
> Reporter: Jean-Daniel Cryans
> Priority: Critical
>
> We had a user that had code that looked like this in a coprocessor's prePut():
> {code}
> if (put.has(expectedKv))
> put.add(kvSayingIFoundIt);
> else
> put.add(kvSayingNotFound);
> {code}
> If you have MSLAB turned *off*, and you have the {{expectedKv}} in your
> {{Put}}, doing a {{Get}} following your insert will only return
> {{kvSayingIFoundIt}} and not the KV you were actually inserting.
> More so, if you only do {{put.has(expectedKv)}}, you will not get anything
> back. Your data seems to be gone.
> The reason is that in {{prePut()}} the timestamp hasn't been set yet, so
> calling {{kv.getTimestamp()}} during the comparisons in {{put.has()}} will
> populate {{kv.timestampCache}} with {{Long.MAX_VALUE}}. Then it will stay in
> the {{MemStore}} with that big timestamp and be filtered out because
> {{TimeRange}} will compare {{Long.MAX_VALUE}} >= {{Long.MAX_VALUE}} and
> return {{SKIP}}.
> And the reason it works correctly with MSLAB *on* is that the KV is cloned in
> {{maybeCloneWithAllocator()}} and the cache is reset.
> Now, I think this has bigger implications. Basically, you can't rely on the
> timestamp at all in {{prePut()}}. I'm sure this can screw someone else in a
> creative way later.
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