Question

In my java code, I access an oracle database table with an select statement.
I receive a lot of rows (about 50.000 rows), so the rs.next() needs some time to process all of the rows.

using ResultSet, the processing of all rows (rs.next) takes about 30 secs

My goal is to speed up this process, so I changed the code and now using a CachedRowSet:

using CachedRowSet, the processing of all rows takes about 35 secs

I don’t understand why the CachedRowSet is slower than the normal ResultSet, because the CachedRowSet retrieves all data at once, while the ResultSet retrieves the data every time the rs.next is called.

Here is a part of the code:

try {
    stmt = masterCon.prepareStatement(sql);
    rs = stmt.executeQuery();

    CachedRowSet crset = new CachedRowSetImpl();
    crset.populate(rs);

    while (rs.next()) {
        int countStar = iterRs.getInt("COUNT");
        ...
    }
} finally {
    //cleanup
}

Answer 1

What makes you think that ResultSet will retrieve the data each time rs.next() is called? It’s up to the implementation exactly how it works – and I wouldn’t be surprised if it fetches a chunk at a time; quite possibly a fairly large chunk.

I suspect you’re basically seeing the time it takes to copy all the data into the CachedRowSet and then access it all – basically you’ve got an extra copying operation for no purpose.