Note that edits sent through this method cannot be batched, and won't be subject to the {@link #setFlushInterval flush interval}. This entails that write throughput will be lower with this method as edits have to be sent out to the wire one by one.
This request enables you to atomically update the value of an existing cell in HBase using a CAS operation. It's like a {@link PutRequest}except that you also pass an expected value. If the last version of the cell identified by your {@code PutRequest} matches the expected value,HBase will atomically update it to the new value.
If the expected value is the empty byte array, HBase will atomically create the cell provided that it doesn't exist already. This can be used to ensure that your RPC doesn't overwrite an existing value. Note however that this trick cannot be used the other way around to delete an expected value atomically. @param edit The new value to write. @param expected The expected value of the cell to compare against.This byte array will NOT be copied. @return A deferred boolean, if {@code true} the CAS succeeded, otherwisethe CAS failed because the value in HBase didn't match the expected value of the CAS request. @since 1.3
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