TAJO-2059: Binary search in BST reader does compare too frequently

[eminency]

Some simple test based on unit test was done with 1M tuples and searching 1M times. Two columns, which are long and double, are used as sort key. Count above is a number of invoking compare().

Current

find : 44 sec count : 42001207

Patch

find : 43 sec count : 20141495

[jihoonson]

Overall, this patch looks good to me. Would you check the test failures?

[eminency]

@jihoonson Thank you for the comment. I'm working on it. I will keep you posted.