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# HBase Performance Tuning

### Column Family

* Restrict to 2 o 3 column family
* Flushing and compactions are done per region basis i.e. if one column family is carrying the bulk of the data bringing on flushes, the adjacent families will also be flushed though the amount of data they carry is small.
* query one column family or the other but usually not both at the one time.

### Row-Key Design

* keep column family, column name as short as possible
* useful shorter rowkey

### Constants

Instead of 

```
Get get = new Get(rowkey);
Result r = htable.get(get);
byte[] b = r.getValue(Bytes.toBytes("cf"), Bytes.toBytes("attr"));  // returns current version of value
```

use

```
public static final byte[] CF = "cf".getBytes();
public static final byte[] ATTR = "attr".getBytes();
...
Get get = new Get(rowkey);
Result r = htable.get(get);
byte[] b = r.getValue(CF, ATTR);  // returns current version of value
```

### Writing to HBase

* Use pre-split regions
* AutoFlush - When performing a lot of Puts, make sure that setAutoFlush is set to false on your [HTable](http://hbase.apache.org/apidocs/org/apache/hadoop/hbase/client/HTable.html) instance. Otherwise, the Puts will be sent one at a time to the RegionServer. Puts added via `htable.add(Put)` and `htable.add( <List> Put)` wind up in the same write buffer. If `autoFlush = false`, these messages are not sent until the write-buffer is filled. To explicitly flush the messages, call `flushCommits`. Calling `close` on the `HTable` instance will invoke `flushCommits`.