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From John Beatty <john.bea...@gmail.com>
Subject Re: question about checkAndPut() expected value parameter when testing row nonexistence
Date Sun, 15 Aug 2010 01:51:18 GMT
Thanks Ryan, but I seem to be missing something then. It NPEs for me.
When running against 0.89.20100726 and providing a null expected value
I get the below stack trace (and works like a champ when I provide a
byte[0]. I also don't see the transformation you're referring to in
HTable.

(for reference,
http://svn.apache.org/viewvc/hbase/branches/0.89.20100726/src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java?view=markup)

java.io.IOException: java.io.IOException: java.lang.NullPointerException
	at org.apache.hadoop.hbase.regionserver.HRegionServer.convertThrowableToIOE(HRegionServer.java:845)
	at org.apache.hadoop.hbase.regionserver.HRegionServer.convertThrowableToIOE(HRegionServer.java:835)
	at org.apache.hadoop.hbase.regionserver.HRegionServer.checkAndMutate(HRegionServer.java:1754)
	at org.apache.hadoop.hbase.regionserver.HRegionServer.checkAndPut(HRegionServer.java:1773)
	at sun.reflect.GeneratedMethodAccessor8.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at org.apache.hadoop.hbase.ipc.HBaseRPC$Server.call(HBaseRPC.java:576)
	at org.apache.hadoop.hbase.ipc.HBaseServer$Handler.run(HBaseServer.java:919)
Caused by: java.lang.NullPointerException
	at org.apache.hadoop.hbase.regionserver.HRegion.checkAndMutate(HRegion.java:1616)
	at org.apache.hadoop.hbase.regionserver.HRegionServer.checkAndMutate(HRegionServer.java:1751)
	... 6 more

On Sat, Aug 14, 2010 at 6:34 PM, Ryan Rawson <ryanobjc@gmail.com> wrote:
> Nulls end up being transformed into byte[0] in HTable and all is well.
>
> On Aug 14, 2010 6:33 PM, "John Beatty" <john.beatty@gmail.com> wrote:
>> There appears to be a disconnect between the API [1] and the
>> implementation [2] of checkAndPut() regarding the expected value
>> parameter when the caller wants to make the put conditional on the row
>> not existing. The javadoc states that the caller should use a null
>> expected value for this purpose, whereas the implementation is
>> checking for a 0-length byte[]. If a null expected value is given,
>> checkAndPut() will NPE; see HRegion.java:1520 in trunk.
>>
>> I believe that null, rather than 0-length byte[], should be used for
>> requiring row non-existence in checkAndPut(). Besides seeming like the
>> right API, a 0-length byte[] is technically a valid row key (and least
>> for a little put/get test I did; I found this surprising).
>>
>> Thoughts?
>>
>> john
>>
>> [1]
> http://hbase.apache.org/docs/r0.89.20100726/apidocs/org/apache/hadoop/hbase/ipc/HRegionInterface.html#checkAndPut(byte[]
> ,
>> byte[], byte[], byte[], byte[], org.apache.hadoop.hbase.client.Put)
>>
>> [2]
> http://svn.apache.org/viewvc/hbase/trunk/src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java?view=markup
>> -- line 1520
>

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