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while( result_set.next() )
{
...
}
I have use System.nanoTime() and calculated the time, for each iteration the time taken is in milliseconds but the overall loop takes about 16s. I am considering a possible reason that the condition test is taking a lot of time, the next() function.
FYI I am connecting to a remote database server and the select query that I make is completed in milliseconds again calculated using the above mentioned method. Any reasons about why it's happening and how I can bring the time to iterate the resultset down to at max a second?
EDIT:
I am dealing with about 4000 records and each record contians about 10 columns each having a size of about 10 chars
EDIT2 Thanks setFetchsize() did the magic, awesome, awesome
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A ResultSet object maintains a cursor that points to the current row in the result set. The term "result set" refers to the row and column data contained in a ResultSet object. Navigational methods − Used to move the cursor around.
Simply iterate on ResultSet object and increment rowCount to obtain size of ResultSet object in java. rowCount = rs. getRow();
There are two types of result sets namely, forward only and, bidirectional.
executeQuery method to obtain the result table from the SELECT statement in a ResultSet object. In a loop, position the cursor using the next method, and retrieve data from each column of the current row of the ResultSet object using getXXX methods. XXX represents a data type. Invoke the ResultSet.
I have set up a table with 4000 rows and 10 columns with 10 characters each and made a simple performance test using the following approach (RealTimeCounter is a class which measures the real time between start() and stop()):
List<String> myResult = new ArrayList<>();
ResultSet rs = s.executeQuery("SELECT * FROM Performance");
RealTimeCounter rtc = new RealTimeCounter();
rtc.start();
while(rs.next()) {
myResult.add(rs.getString(1));
}
rtc.stop();
System.out.println(rtc);
Results:
So, the fetch size does have a significant impact on the execution speed.
Note that, on the other hand, the fetch size has some impact on memory consumption. Interestingly enough, a quick analysis using Runtime.getRuntime().freeMemory(); before and after the above code showed that the impact is much less than I would expect, though. The numbers I got are:
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