@Test
  public void testQualifierFilterWithEmptyColumn() throws IOException {
    long colsPerRow = 2;
    long expectedKeys = colsPerRow / 2;
    Filter f = new QualifierFilter(CompareOperator.EQUAL, new BinaryComparator(QUALIFIERS[0]));
    Scan s = new Scan();
    s.setFilter(f);
    verifyScanNoEarlyOut(s, this.numRows, expectedKeys);

    expectedKeys = colsPerRow / 2;
    f = new QualifierFilter(CompareOperator.EQUAL, new BinaryComparator(QUALIFIERS[1]));
    s = new Scan();
    s.setFilter(f);
    verifyScanNoEarlyOut(s, this.numRows, expectedKeys);

    expectedKeys = colsPerRow / 2;
    f = new QualifierFilter(CompareOperator.GREATER, new BinaryComparator(QUALIFIERS[0]));
    s = new Scan();
    s.setFilter(f);
    verifyScanNoEarlyOut(s, this.numRows, expectedKeys);

    expectedKeys = colsPerRow;
    f = new QualifierFilter(CompareOperator.GREATER_OR_EQUAL, new BinaryComparator(QUALIFIERS[0]));
    s = new Scan();
    s.setFilter(f);
    verifyScanNoEarlyOut(s, this.numRows, expectedKeys);
  }
Test qualifierFilter with empty qualifier column
hbase-server/src/test/java/org/apache/hadoop/hbase/filter/TestQualifierFilterWithEmptyQualifier.java