[jira] [Commented] (HBASE-10254) Optionally return null when attempting to Increment KeyValue that doesn't exist

[James Taylor (JIRA)]

    [ 
https://issues.apache.org/jira/browse/HBASE-10254?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13859064#comment-13859064
 ] 

James Taylor commented on HBASE-10254:
--------------------------------------

Here's the simplified version of Increment. How will this perform relative to 
HRegion.increment() ? If all increments are done through my new coprocessor, 
are there edge cases that aren't covered

package com.salesforce.phoenix.coprocessor;

import java.io.IOException;

import org.apache.hadoop.hbase.KeyValue;
import org.apache.hadoop.hbase.client.Get;
import org.apache.hadoop.hbase.client.Put;
import org.apache.hadoop.hbase.client.Result;
import org.apache.hadoop.hbase.coprocessor.BaseEndpointCoprocessor;
import org.apache.hadoop.hbase.coprocessor.RegionCoprocessorEnvironment;
import org.apache.hadoop.hbase.io.TimeRange;
import org.apache.hadoop.hbase.regionserver.HRegion;

import com.salesforce.phoenix.schema.PDataType;
import com.salesforce.phoenix.util.KeyValueUtil;

public class SequenceEndpointImpl extends BaseEndpointCoprocessor {

    @Override
    public RegionCoprocessorEnvironment getEnvironment() {
        return (RegionCoprocessorEnvironment)super.getEnvironment();
    }

    public Long incrementColumnValue(byte[] row, byte[] family, byte[] 
qualifier, 
            long amount, TimeRange tr, long incrementTimestamp, boolean 
writeToWAL) throws IOException {
        RegionCoprocessorEnvironment env = this.getEnvironment();
        HRegion region = env.getRegion();
        
        region.startRegionOperation();
        try {
            Integer lid = region.getLock(null, row, true);
            try {
                Get get = new Get(row);
                get.setTimeRange(tr.getMin(), tr.getMax());
                get.addColumn(family, qualifier);
                Result result = region.get(get);
                if (result.isEmpty()) {
                    return null;
                }
                KeyValue existingKV = result.raw()[0];
                long value = 
PDataType.LONG.getCodec().decodeLong(existingKV.getBuffer(), 
existingKV.getValueOffset(), null);
                value += amount;
                byte[] valueBuffer = new byte[PDataType.LONG.getByteSize()];
                PDataType.LONG.getCodec().encodeLong(value, valueBuffer, 0);
                Put put = new Put(row);
                KeyValue newKV = KeyValueUtil.newKeyValue(row, family, 
qualifier, incrementTimestamp, valueBuffer);
                put.add(newKV);
                region.put(put, writeToWAL);
                return value;
            } finally {
                region.releaseRowLock(lid);
            }
        } finally {
            region.closeRegionOperation();
        }
    }

}


> Optionally return null when attempting to Increment KeyValue that doesn't 
> exist
> -------------------------------------------------------------------------------
>
>                 Key: HBASE-10254
>                 URL: https://issues.apache.org/jira/browse/HBASE-10254
>             Project: HBase
>          Issue Type: Bug
>            Reporter: James Taylor
>
> Instead of creating a new KeyValue starting from 0 when an Increment is done 
> on a row that doesn't exist, we should optionally return null. A Get is 
> already being done, so it's easy to detect this case. This can be done in a 
> backward compatible manner if the behavior is done optionally. In addition, 
> Increment does not allow me to specify the timestamp to use for the KeyValue. 
> This should be added as well.



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