I have an application which has 10 million rows and 1000 columns in Oracle. Each value has a different set of calculations that are stored in User Defined PLSQL functions.
Data is displayed in form of data grid. When a user updates any value, the calculation is performed using plsql function and value is stored in database. Is there an easy way through which calculation is performed on the fly and i get maximum performance ?
I'm programming an android app where I want to send large sets of data from an MySQL Table to the app and write this data to an SQLite database.So I know i have send an HttpRequest and I can send data with json, but how can I handle large datasets like tables?I think its no good idea to just concatinate a string together in php and then send it?
View Replies View RelatedOur client has a user facing web application running on Jboss. There is a separate admin application (in its own ear) but deployed on same Jboss server on which user facing web application is running.
They need a screen to upload large amount of data into database. Their original files were in excel with size > 60 mb. We suggested following to them:
a. Change upload format to CSV - this brought down file sizes to 25-30 mb
b. Upload process will be MDB - asynchronous processing of data so that admin web app does not stop responding
We also suggested following to them:
a. Host admin app on a different machine so that user facing site does not respond slow during data processing
b. We can provide incremental upload feature and they should upload files in the chunks of 4-5 mb, specifically if they have user a web page to upload such files - they don't buy this argument though.
c. Data processing can be a separate script instead of a part of admin web application. They can FTP files to a designated location and this script will process those files.
I have following questions:
Q1 - Have you seen upload of such large datafiles to a web application? I see sites like Zoho CRM or Salesforce do not support such data imports and mostly fail or not respond.
Q2 - Is there a set of guidelines/best practices to upload large data files of this nature? How do insurance companies or others with enormous set of data accomplish such tasks (what is the architecture of such programs)?
I have a huge data set 10000+ rows which I need to show in the tableview. It take a lot of time to render the UI and is slow.
View Replies View Relatedi have to write more than 100000 rows in a excel sheet (file size more than 20 MB) via java.
when i use XSSF, i am getting below Error.
java.lang.OutOfMemoryError: Java heap space
at org.apache.xmlbeans.impl.store.Saver$TextSaver.resize(Saver.java:1592)
at org.apache.xmlbeans.impl.store.Saver$TextSaver.preEmit(Saver.java:1223)
at org.apache.xmlbeans.impl.store.Saver$TextSaver.emit(Saver.java:1144)
[Code]....
when i use HSSF , i am getting the below Error.
java.lang.OutOfMemoryError: Java heap space
I have tried increasing the java heap size , by giving upto -Xms1500m -Xmx2048m
I want to monitor performance of web application, running in java JVM(Java version 1.5.0_22) using tomcat web server, for a given functionality want to find, methods and sql queries how much time taking for execution. i am looking for setting and free tools available.
View Replies View RelatedHave you ever did a design for an application with requirements such as X number of anticipated users of the application in the next 5 years, and should still perform as expected.
How do you usually implement design solution for this? the only solution I am familiar with when faced with this type of requirement is the use of EJBs (is that even a correct design for it?).
How to improve jsp page load performance and i have use sessions in jsp page.i tried using with include tag rather than using jsp:include. also
View Replies View RelatedVisual effects such as Transitions perform very poor on linux "wheezy" compared to windows. I noticed this on different PC's, checked for Java7 and Java8. If the UI contains many objects then the transition sometimes does not even appear.
I do not think this is graphic card related since videos play quite ok.
I use the default ATI driver without Xorg.conf file and installed the xcompmgr
and tried several options, such as
Option "Composite" "Enable"
or
Option "backingstore" "true"
Option "AllowGLXWithComposite" "true"
This did not speed up things, are there other things that I could do to improve the performance ?
As the JRE environments and usage of applets has become more and more secure in through the evolution of enhancements to the JRE we have noticed a performance degradation in usage of these applets and launching of them.
As our customers are in the business to business environment they utilize our applets that are delivered from the server to the client. We are looking at ways to reduce the time to validate that the certificates are still valid. we are looking for ways to provide a means for our customers to validate against a CRL on our server or to cache the the checks against the OCSP so that not each and every client accessing our server needs to go out to the third party sites to get the checks completed.
Is there a means to store this information on our server and have the JRE validate against that system rather than the normal OSCP...
In our product we show search histories on the UI, means what ever user searches we make a history for that search in the database and show it on the UI.
At present we show duplicate histories also. for ex- if a user do a search with some criteria (say, abc), now if the user do search again with same criteria (abc), we show it twice on our history page.
What we need to do -
we need to remove the duplication, and only to show the search histories once if they have same criteria. also we need to save it only once in the database. means we neither display the same search histories nor store them in the database. ofcourse if we store it only once, it will be displayed only once. so we need logic in our storing part here.
Approaches we are trying -
Approach 1 - We thought to remove duplicate search histories by comparing their criteria's, but here the problem is that single search history itself can have so many criteria's and we store around 30 search histories in the database, so if we compare criteria of all of them one by one. we will loose the performance. so we dropped this approach.
Approach 2 - The second approach we are thinking is, at the time of creation of search histories, we will generate checksum based on their criteria, so if the criteria is same for two search histories the checksum generated would be same, and before creating (storing into database) the search history we first check if the checksum is already exist in the search history table for any search history or not, if it is already there, don't create the search history, as it is already there.
The problems with this approach is -
First Problem - we will need to create one more column in the Table which will impact our upgrade process, and we don't want to have an upgrade impact.
Second Problem - if user changed the sequence of criteria of search, for e.g. name criteria first and then number criteria but the values are same. and in the another search number criteria first then name criteria and values are same as first search, here the search results would be same as the criteria are same but only the sequence is different, so in this case two histories will get created (as we generate checksum based on criteria so if sequence gets changed checksum would also be different), however we want only one search history in this situation. we don't want to consider the sequence.
We store the search histories in XML format and we convert this xml to blob to store it into database, i thought to first sort them then generate checksum, but as they are in xml format, so i can't even sort them because the tags are similar to all the criteria's.
I am using infrared for monitoring performance of j2ee web application(using hibernate and spring),deploying on tomcat 7.0.23 and jdk 1.6.17.here infrared shows only http layer not sql and jsp layer.
View Replies View RelatedI found an exercise online to create a small program . I have this code that I have done so far:
import java.util.Scanner;
public class Test {
public static void main(String args[]) {
Scanner sc = new Scanner(System.in);
long a = sc.nextLong(); long b = sc.nextLong();
long count = 0; // counter
[code]....
The program should read the numbers a and b and list how many numbers between a and b are divisible by either 2, 3 or 5. If the user types the number 5 and then 8.... it would look at all the numbers in between - 5,6,7,8 and check if any of them are divasable by either 2,3 or 5. And since the numbers 5,6,8 are it would return the number 3 to the user..Now the problem is that this program only works for small numbers, but when I try to input numbers such as 123456789012345678 and 876543210987654321... it doesn't run at all.
So there needs to be a quicker way on how the program checks the numbers divisibility instead of checking each one. Here is where I am lost. How to fix the program that it will read bigger numbers such as a=123456789012345678 b=87654321098765432..There must be a quicker way ...something that can modify the code so it finishes in the matter of seconds not hours. Something that will fasten the process of checking if the numbers are dividable.
I want to migrate some large application code base's from jdk1.4 to jdk1.6.
1. Is there any tool/s available that can be used for this migration (Because manually it is very difficult for a application with almost 15,000 java files and 15 * 10^6 KLOC within a limited time frame).
2. Steps that should be followed in such cases.
3, If any tool is not available for such activity what are the salient points that are needed to be considered while migrating.
I have a simple display method in a java project as given below:
public void displayInfo() {
for(Student student : studentdB){
System.out.println(student.toString() + "
");
}
I would want to use one of Swing components to display the students instead of displaying them on the stdout. How I could go about calling this method in some Swing components that can display all the students in the studentdb?
I need to encrypt/decrypt file contents using RSA . But the default nature of RSA I could not upload files larger than 177 bytes for key length 1024 bytes . How it can avoid , I look it for a 100 times yet...
I attach my encryption files here ...
See attached files for more details ...
What I'm tasked to do, is to make a simple Java class that forms a "V" based on whatever height the user would desire, made out of stars "*", and spaces " ".
For example, if a user desires a "V" with a height of 3, it would look print out something like;
* *
* *
*
Where a "V" with a height of 5 would look something like:
* *
* *
* *
* *
*
(That one didn't look too good, but you get the point, it's suppose to be 5 "high" and shaped like a "V"). The problem I have, is that I don't see what loops within loops within loops I would need to build something like this.
All the easy stuff like asking the user what height they want and such, I can handle, but I don't see how this thing is suppose to be coded, to print out a decent-looking and right-sized "V" in the console.
public static void main(String[] args) {
int height = 3;
for (int i = 0; i < height; i++) {
for (int j = 0; j < 2/(height+1)+1; j++) {
if(j == i) {
[Code] ....
Looked like something of a good start, and it drew me half (!) of the "V" in the size I wanted. Am I on to it here, or am I on the moon in terms of progress? I need the entire "V", not just a nice "".
I am calculating an exponent without using BigInteger. However, I find that using long is not enough to handle my code. Is there a way to handle large numbers without using BigInteger?
public static void main (String[] args){
int base = 3;
int exponent;
long total = 1L;
boolean n;
Scanner input = new Scanner(System.in);
[code].....
In my programming class we need to create a large test array of Longs to iteratively sum/reverse the array and recursively sum/reverse the array.creating the array and where to go from there.
View Replies View RelatedWe have a website used for downloading large files as large as 6gb and sometimes larger. We have all files in FTP server. The websit is JSP/Servlet /Tomcat combination. Below is code sample. I need a solution to increase the download speed. I understand it is bound to network bandwidth but are the steps that we need to take while we have such large files.I read about multipart downloads,gunzip streaming.
//first connect to FTP server and login and keep connection
Calendar cal=Calendar.getInstance();
startTime=cal.getTime();
fis=ftp.downloadFile(ftpclient,separator+resourceID);
response.setContentType("application/*");
response.setHeader("Content-Disposition", "attachment; filename="" + downloadFileName + "";");
byte[] bytes = new byte[1024];
[code]....
I've written a small program that does factorial by recursion.
I think it works properly for small input like 10, but it stops working properly
if the input becomes large, like 100.
If I try any large input, I get a zero.
Why I am getting 0s.
import java.util.Scanner;
public class myFactorialRecursion {
public static void main(String[] args) {
[Code].....
reading a large json file which is really huge and it contains pair of id and URL in a array as shown below.. i need to get this all id and URL from this file in my java code and need to perform operations . how to read such a big file and store the contents in java code to process it further.
{
"Array": [
{
"id": "1test",
"URL": "http://servername/test/1test.html"
},
{
"id": "2test",
"URL": "http://servername/test/2test.html"
}
....................many id and URL in the same Array which makes the file Huge..
]
}
I have a program that works, but I would like to know an easier way to record and print from a large array.
Here is what I have
package pa2;
import java.io.IOException;
public class PA2Delegate {
//long[] array = new long[100000];
int arraySize = 100000;
int iterations = 9999;
Long[] array;
[code].....
I have application written in rest with Jersey-Jackson for JSON processing. All the resources produce and consume JSON. Now, the problem is, it is a server intensive application and large number of request will be hitting the server with large JSON request object. Now, because of this reason, when the JSON object gets converted in to Java object with String fields in it mapping to JSON request values large number of string objects are getting created which is resulting in frequent GC.
View Replies View RelatedRight now I have 12 methods, each roughly 40 lines long, and I am contemplating whether I should simplify some of the pairs (12 methods, but every other method is very similar to each other, so 6 pairs) into one method.
The main pro of simplifying them is that my class will be much smaller, right now its about 555 lines of code. However a con is that it might not be as straight forward, at first glance at least.
Here is what I am talking about. Two original methods that are very similar:
void rotateRightClockwise(int rotations){//rotates FRONTS's RIGHT! CONFIRMED
String a, b, c;//temp values
for(int i = 1; i <= rotations; i++){//confirmed
a = cube.cube[1][2].square[2];//3
b = cube.cube[1][2].square[5];//6
c = cube.cube[1][2].square[8];//9
[Code] ....
The only difference between these two methods, other than the last chunk for each method, is the I have to change the 2nd square bracket, [], values from lines 9-23 for cube[][]. That's it. So I am thinking of combining them into something like this...
private void rotateRight(int rotations, int x, int y){
String a, b, c;//temp values
for(int i = 1; i <= rotations; i++){//confirmed
a = cube.cube[1][2].square[2];//3
b = cube.cube[1][2].square[5];//6
c = cube.cube[1][2].square[8];//9
[Code] .....
And then after calling this similar method, I would finish off the last chunk from each methods, since they are too different (ie lines 26-38).
The reason why I ask this is because I am trying to build up my portfolio and I want to know if the employer would look at this and say "that was a good move by compacting your code" or "this is not that straight forward".
I need to download large amount files, what should I care, Is the following code have problem on download large files
private static byte[] load(String filename) throws IOException {
FileInputStream fis = new FileInputStream(filename);
byte[] data = new byte[fis.available()];
fis.read(data);
fis.close();
return data;
}