public class CheckAndDeleteExample {
public static void main(String[] args) throws IOException {
Configuration conf = HBaseConfiguration.create();
HBaseHelper helper = HBaseHelper.getHelper(conf);
helper.dropTable("testtable");
helper.createTable("testtable", "colfam1", "colfam2");
helper.put("testtable",
new String[] { "row1" },
new String[] { "colfam1", "colfam2" },
new String[] { "qual1", "qual1", "qual2", "qual2", "qual3", "qual3" },
new long[] { 1, 2, 3, 4, 5, 6 },
new String[] { "val1", "val2", "val3", "val4", "val5", "val6" });
System.out.println("Before delete call...");
helper.dump("testtable", new String[]{ "row1" }, null, null);
HTable table = new HTable(conf, "testtable");
// vv CheckAndDeleteExample
Delete delete1 = new Delete(Bytes.toBytes("row1"));
delete1.deleteColumns(Bytes.toBytes("colfam1"), Bytes.toBytes("qual3")); // co CheckAndDeleteExample-1-Delete1 Create a new Delete instance.
boolean res1 = table.checkAndDelete(Bytes.toBytes("row1"),
Bytes.toBytes("colfam2"), Bytes.toBytes("qual3"), null, delete1); // co CheckAndDeleteExample-2-CAS1 Check if column does not exist and perform optional delete operation.
System.out.println("Delete successful: " + res1); // co CheckAndDeleteExample-3-SOUT1 Print out the result, should be "Delete successful: false".
Delete delete2 = new Delete(Bytes.toBytes("row1"));
delete2.deleteColumns(Bytes.toBytes("colfam2"), Bytes.toBytes("qual3")); // co CheckAndDeleteExample-4-Delete2 Delete checked column manually.
table.delete(delete2);
boolean res2 = table.checkAndDelete(Bytes.toBytes("row1"),
Bytes.toBytes("colfam2"), Bytes.toBytes("qual3"), null, delete1); // co CheckAndDeleteExample-5-CAS2 Attempt to delete same cell again.
System.out.println("Delete successful: " + res2); // co CheckAndDeleteExample-6-SOUT2 Print out the result, should be "Delete successful: true" as the column now already exists.
Delete delete3 = new Delete(Bytes.toBytes("row2"));
delete3.deleteFamily(Bytes.toBytes("colfam1")); // co CheckAndDeleteExample-7-Delete3 Create yet another Delete instance, but using a different row.
try{
boolean res4 = table.checkAndDelete(Bytes.toBytes("row1"),
Bytes.toBytes("colfam1"), Bytes.toBytes("qual1"), // co CheckAndDeleteExample-8-CAS4 Try to delete while checking a different row.
Bytes.toBytes("val1"), delete3);
System.out.println("Delete successful: " + res4); // co CheckAndDeleteExample-9-SOUT4 We will not get here as an exception is thrown beforehand!
} catch (Exception e) {
System.err.println("Error: " + e);
}
// ^^ CheckAndDeleteExample
System.out.println("After delete call...");
helper.dump("testtable", new String[]{ "row1" }, null, null);
}