Scala: Creating a HBase table with pre splitting region based on Row Key - scala

Question

I have three RegionServers. I want to evenly distribute a HBase table onto three regionservres based on rowkeys which I have already identified (say, rowkey_100 and rowkey_200). It can be done from hbase shell using:
create 'tableName', 'columnFamily', {SPLITS => ['rowkey_100','rowkey_200']}
If I am not mistaken, this 2 split points will create 3 regions, and the first 100 rows will go to the 1st regionserver, next 100 rows will be in 2nd regionserver and the remaining rows in last regionserver. I want to do the same thing using scala code. How can I specify this in scala code to split table into regions?

Answer 1

Below is a Scala snippet for creating a HBase table with splits:
val admin = new HBaseAdmin(conf)
if (!admin.tableExists(myTable)) {
val htd = new HTableDescriptor(myTable)
val hcd = new HColumnDescriptor(myCF)
val splits = Array[Array[Byte]](splitPoint1.getBytes, splitPoint2.getBytes)
htd.addFamily(hcd)
admin.createTable(htd, splits)
}
There are some predefined region split policies, but in case you want to create your own way of setting split points that span your rowkey range, you can create a simple function like the following:
def autoSplits(n: Int, range: Int = 256) = {
val splitPoints = new Array[Array[Byte]](n)
for (i <- 0 to n-1) {
splitPoints(i) = Array[Byte](((range / (n + 1)) * (i + 1)).asInstanceOf[Byte])
}
splitPoints
}
Just comment out the val splits = ... line and replace createTable's splits parameter with autoSplits(2) or autoSplits(4, 128), etc.

Answer 2

This java code can help
HTableDescriptor td = new HTableDescriptor(TableName.valueOf("tableName"));
HColumnDescriptor cf = new HColumnDescriptor("cf".getBytes());
td.addFamily(cf);
byte[][] splitKeys = new byte[] {key1.getBytes(), key2.getBytes()};
HBaseAdmin dbAdmin = new HBaseAdmin(conf);
dbAdmin.createTable(td, splitKeys);