Get Column Names in HBase Thrift C++? - visual-c++

Question

I need to get the list of column qualifiers available in a HBase table.
Suppose I have a table 'Customers' with column 'info:Age' and 'contact:PhoneNo'. To get the list of column families I see there's a method 'getColumnDescriptors' which returns the value 'info' and 'contact'.
But how to retrieve the full column names 'info:Age' and 'contact:PhoneNo' from the table or atleast the qualifiers 'Age' and 'PhoneNo' alone.
With the method 'getRowWithColumns' I am able to get the list of column names where I have to pass the row key value.
Will I be able to achieve this through any other convenient way?

Answer 1

Here is a working solution in Java as you asked, you just have to change a few things to translate it to C++.
Basically this method will scan the table and retrieves the column qualifiers, then I add them into a list if this list does not already contains it.
Here, I look at all the rows, but if all your rows always have the same columns, you can just scan the first row, using a Get for example (look at the HBase documentation, I've written several examples there).
public ArrayList<String> getColumnName(String tablename) {
ArrayList<String> properties = new ArrayList<String>();
try {
Table table = this.connection.getTable(TableName.valueOf(tablename));
Scan scan = new Scan();
ResultScanner rs = table.getScanner(scan);
try {
for (Result r = rs.next(); r != null; r = rs.next()) {
for (Cell c : r.rawCells()) {
String family = new String(CellUtil.cloneFamily(c));
String qualifier = new String(CellUtil.cloneQualifier(c));
System.out.println("Column Family : "+ family);
System.out.println("Column Qualifier : " + qualifier);
if (!properties.contains(qualifier))
properties.add(new String(CellUtil.cloneQualifier(c)));
}
}
} finally {
rs.close(); // always close the ResultScanner!
}
} catch (IOException e) {
e.printStackTrace();
}
return properties;
}