[HBASE-6269] Lazyseek should use the maxSequenseId StoreFile's KeyValue as the latest KeyValue

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.94.0
• Fix Version/s: 0.94.1, 0.95.0
• Component/s: regionserver
• Hadoop Flags: Reviewed
• Assignee: ShiXing
• Reporter: ShiXing
• Created: 26/Jun/12 09:21
• Updated: 26/Feb/13 08:16
• Resolved: 03/Jul/12 10:44

Description

When I fix the bug HBASE-6195, there is happened to find sometimes the test case will fail, https://builds.apache.org/job/HBase-0.94/259/.

If there are two Put/Increment with same row, family, qualifier, timestamp and different memstoreTS, after each Put/Increment, we do a memstore flush. So there will be two StoreFile with same KeyValue(except memstoreTS and SequenceId).

When I got the row, I always got the old records, the test case like this:

  public void testPutWithMemStoreFlush() throws Exception {
    Configuration conf = HBaseConfiguration.create();
    String method = "testPutWithMemStoreFlush";
    byte[] tableName = Bytes.toBytes(method);
    byte[] family = Bytes.toBytes("family");;
    byte[] qualifier = Bytes.toBytes("qualifier");
    byte[] row = Bytes.toBytes("putRow");
    byte[] value = null;
    this.region = initHRegion(tableName, method, conf, family);
    Put put = null;
    Get get = null;
    List<KeyValue> kvs = null;
    Result res = null;
    
    put = new Put(row);
    value = Bytes.toBytes("value0");
    put.add(family, qualifier, 1234567l, value);
    region.put(put);
    System.out.print("get value before flush after put value0 : ");
    get = new Get(row);
    get.addColumn(family, qualifier);
    get.setMaxVersions();
    res = this.region.get(get, null);
    kvs = res.getColumn(family, qualifier);
    for (int i = 0; i < kvs.size(); i++) {
      System.out.println(Bytes.toString(kvs.get(i).getValue()));
    }

    region.flushcache();
    
    System.out.print("get value after flush after put value0 : ");
    get = new Get(row);
    get.addColumn(family, qualifier);
    get.setMaxVersions();
    res = this.region.get(get, null);
    kvs = res.getColumn(family, qualifier);
    for (int i = 0; i < kvs.size(); i++) {
      System.out.println(Bytes.toString(kvs.get(i).getValue()));
    }
    
    put = new Put(row);
    value = Bytes.toBytes("value1");
    put.add(family, qualifier, 1234567l, value);
    region.put(put);
    System.out.print("get value before flush after put value1 : ");
    get = new Get(row);
    get.addColumn(family, qualifier);
    get.setMaxVersions();
    res = this.region.get(get, null);
    kvs = res.getColumn(family, qualifier);
    for (int i = 0; i < kvs.size(); i++) {
      System.out.println(Bytes.toString(kvs.get(i).getValue()));
    }
    region.flushcache();
    System.out.print("get value after flush after put value1 : ");
    get = new Get(row);
    get.addColumn(family, qualifier);
    get.setMaxVersions();
    res = this.region.get(get, null);
    kvs = res.getColumn(family, qualifier);
    for (int i = 0; i < kvs.size(); i++) {
      System.out.println(Bytes.toString(kvs.get(i).getValue()));
    }
    
    put = new Put(row);
    value = Bytes.toBytes("value2");
    put.add(family, qualifier, 1234567l, value);
    region.put(put);
    System.out.print("get value before flush after put value2 : ");
    get = new Get(row);
    get.addColumn(family, qualifier);
    get.setMaxVersions();
    res = this.region.get(get, null);
    kvs = res.getColumn(family, qualifier);
    for (int i = 0; i < kvs.size(); i++) {
      System.out.println(Bytes.toString(kvs.get(i).getValue()));
    }
    region.flushcache();
    System.out.print("get value after flush after put value2 : ");
    get = new Get(row);
    get.addColumn(family, qualifier);
    get.setMaxVersions();
    res = this.region.get(get, null);
    kvs = res.getColumn(family, qualifier);
    for (int i = 0; i < kvs.size(); i++) {
      System.out.println(Bytes.toString(kvs.get(i).getValue()));
    } 
  }

and the result print as followed:

get value before flush after put value0 : value0
get value after flush after put value0 : value0
get value before flush after put value1 : value1
get value after flush after put value1 : value0
get value before flush after put value2 : value2
get value after flush after put value2 : value0

I analyze the code for StoreFileScanner with lazy seek, the StoreFileScanners are sorted by SequenceId, so the latest StoreFile is on the top KeyValueHeap, and the KeyValue for latest StoreFile will comapre to the second latest StoreFile, but the second latest StoreFile generated the fake row for same row, family, qualifier excepts the timestamp( maximum), memstoreTS(0). And the latest KeyValue recognized as not latest than the second latest.

Issue Links

• is related to: HBASE-6195 Increment data will be lost when the memstore is flushed