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  • Need help optimizing MYSQL query with join

    - by makeee
    I'm doing a join between the "favorites" table (3 million rows) the "items" table (600k rows). The query is taking anywhere from .3 seconds to 2 seconds, and I'm hoping I can optimize it some. Favorites.faver_profile_id and Items.id are indexed. Instead of using the faver_profile_id index I created a new index on (faver_profile_id,id), which eliminated the filesort needed when sorting by id. Unfortunately this index doesn't help at all and I'll probably remove it (yay, 3 more hours of downtime to drop the index..) Any ideas on how I can optimize this query? In case it helps: Favorite.removed and Item.removed are "0" 98% of the time. Favorite.collection_id is NULL about 80% of the time. SELECT `Item`.`id`, `Item`.`source_image`, `Item`.`cached_image`, `Item`.`source_title`, `Item`.`source_url`, `Item`.`width`, `Item`.`height`, `Item`.`fave_count`, `Item`.`created` FROM `favorites` AS `Favorite` LEFT JOIN `items` AS `Item` ON (`Item`.`removed` = 0 AND `Favorite`.`notice_id` = `Item`.`id`) WHERE ((`faver_profile_id` = 1) AND (`collection_id` IS NULL) AND (`Favorite`.`removed` = 0) AND (`Item`.`removed` = '0')) ORDER BY `Favorite`.`id` desc LIMIT 50;

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  • How can I intercept a Tomcat request at socket level?

    - by Miguel Pardal
    Hi, I'm doing a performance study for a web application framework running on Apache Tomcat 6. I'm trying to measure the time overhead of handling HTTP requests. What I would like to do is: / // just before first request byte is read long t1 = System.nanoTime(); // request is processed... // just after final byte is written to response long t2 = System.nanoTime(); / Then I would compute the total time (t2 - t1). Is there a way to do this? Thanks for your help!

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  • Speed-up of readonly MyISAM table

    - by Ozzy
    We have a large MyISAM table that is used to archive old data. This archiving is performed every month, and except from these occasions data is never written to the table. Is there anyway to "tell" MySQL that this table is read-only, so that MySQL might optimize the performance of reads from this table? I've looked at the MEMORY storage engine, but the problem is that this table is so large that it would take a large portion of the servers memory, which I don't want. Hope my question is clear enough, I'm a novice when it comes to db administration so any input or suggestions are welcome.

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  • Wordpress Custom Query

    - by InnateDev
    I have posts that use a custom field for start date and end date. Query_posts returns an array of posts that exist in the category I'm filtering. How do I query posts using this custom field that has date i.e. 03/11/2010 and not the full array. Pagination works on the full array so it returns all posts. I can use an if else to only show the posts newer that today, then pagination doesn't work. Would I have to build a custom mysql query?

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  • Is memcached a dinosaur in comparison to Redis?

    - by Industrial
    Hi everyone, I have worked quite a bit with memcached the last weeks and just found out about Redis. When I read this part of their readme, I suddenly got a warm, cozy feeling in my stomach: Redis can be used as a memcached on steroids because is as fast as memcached but with a number of features more. Like memcached, Redis also supports setting timeouts to keys so that this key will be automatically removed when a given amount of time passes. This sounds amazing. I'd also found this page with benchmarks: http://www.ruturaj.net/redis-memcached-tokyo-tyrant-mysql-comparison So, honestly - Is memcache really that old dinousaur that is a bad choice from a performance perspective when compared to this newcomer called Redis? I haven't heard lot about Redis previously, thereby the approach for my question!

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  • sql query need a help.

    - by benjamin button
    If i have a table with two fields.customer id and order. let's say i have in total order ID 1,2,3,4 all the customer can have all the four orders.like below 1234 1 1234 2 1234 3 1234 4 3245 3 3245 4 5436 2 5436 4 you can see above that 3245 customer doesnt have order id 1 and 2. how could i print in the query output like 3245 1 3245 2 5436 1 5436 3 EDIT: i dont order table but i have list of order's like we can hard code it in the query(1,2,3,4) i dont have an orders table.

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  • Why do a small amount of add/deletes take several seconds in EF4?

    - by TomWij
    Using the Entity Framework 4. I have created a Code First database in the past and a piece of code needs to delete and add 16 objects, this takes 6 seconds each. That's 300+ ms for each query! The deletes/adds occur in a foreach scope and there is a SaveChanges() outside the foreach. In the above image you see that each takes 6 seconds, which is 34% of the time, for 16 calls. That doesn't sound normal to me... Why is this and how can I improve the performance? If there is no solution: Are there any workarounds I can use? It would be a pain to rewrite my project...

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  • CoreData and many NSArrayController

    - by unixo
    In my CoreData Application, I've an outline view on left of main window, acting as source list (like iTunes); on the right I display a proper view, based on outline selection. Each view has its components, such as table view, connected to array controller, owned by the specific view. Very often different views display same data, for example, a table view of the same entity. From a performance point of view, is better to have a single array controller per entity and share it between all views or does CoreData cache avoid memory waste?

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  • Multiple calculations on the same set of data: ruby or database?

    - by Pierre
    Hi, I have a model Transaction for which I need to display the results of many calculations on many fields for a subset of transactions. I've seen 2 ways to do it, but am not sure which is the best. I'm after the one that will have the least impact in terms of performance when data set grows and number of concurrent users increases. data[:total_before] = Transaction.where(xxx).sum(:amount_before) data[:total_after] = Transaction.where(xxx).sum(:amount_after) ... or transactions = Transaction.where(xxx) data[:total_before]= transactions.inject(0) {|s, e| s + e.amount_before } data[:total_after]= transactions.inject(0) {|s, e| s + e.amount_after } ... Which one should I choose? (or is there a 3rd, better way?) Thanks, P.

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  • Query multiple currencies

    - by TiuTalk
    I need store multiple currencies on my database... Here's the problem: Example Tables: [ Products ] id (INT, PK) name (VARCHAR) price (DECIMAL) currency (INT, FK) [ Currencies ] id (INT, PK) name (VARCHAR) conversion (DECIMAL) # To U$ I'll store the product price with the currency selected by the user... Later I need to search the products using a price interval like "Search products with price from U$ 50 to U$ 100" and I need the system convert these values "on the fly" to run the SQL Query and filter the products. And I really don't know how to make this query... :/

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  • How taxing would a game map grid be to a web browser?

    - by Vilx-
    Suppose we're making a strategy game (think Civilization) in a web browser. The game has a visible map portion - say 30x30 squares. Each square is 30x30px and has several overlaid images - the terrain, resources, units, roads, etc. The classical way of drawing this would be with a huge <table> where each cell would contain absolutely positioned images. It would probably be rendered in Javascript to reduce traffic. But it's still several thousand images and a huge table. Can the browser take it? Will the performance not drop below any acceptable limits? Alternatively I could keep a pre-rendered map image with as many overlays as possible, but that would be more work, I think.

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  • DataTable linq query iteration

    - by Ravi
    Hi, I want to Enumerate Linq Query. Below i specified example. EX: DataTable _slidingDataTable = new DataTable("test"); for(int i=0; i<5;i++) { DataRow row = _slidingDataTable.NewRow(); startPosition = DateTime.Now; for(int i=0; i<5;i++) { _slidingDataTable.Columns.Add("TransferTime"); row[columnName] = startPosition ; _slidingDataTable.Columns.Add("TransferData"); row[columnName] = "Test"+i; } _slidingDataTable.Rows.Add(row); } var query1 = from myRow in _slidingDataTable.AsEnumerable() where myRow.Field<DateTime>("TransferTime") == startPosition select myRow; This query output should be collection of rows. How to get collection row & iterate.

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  • MySQL - How do I insert an additional where clause into this full-text search query

    - by Steven
    I want to add a WHERE clause to a full text search query (to limit to past 24 hours), but wherever I insert it I get Low Level Error. Is it possible to add the clause and if so, how? $query = "SELECT * WHERE story_time > time()-86400 AND MATCH (story_title) AGAINST ('".validate_input($_GET['q'])."' IN BOOLEAN MODE) AS Relevance FROM ".$config['db']['pre']."stories WHERE MATCH (story_title) AGAINST ('+".validate_input($_GET['q'])."' IN BOOLEAN MODE) HAVING Relevance > 0.2 ORDER BY Relevance DESC, story_time DESC LIMIT ".validate_input(($_GET['page']-1)*10).",10";

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  • Performance issues in android game

    - by user1446632
    I am making an android game, but however, the game is functioning like it should, but i am experiencing some performance issues. I think it has something to do with the sound. Cause each time i touch the screen, it makes a sound. I am using the standard MediaPlayer. The method is onTouchEvent() and onPlaySound1(). Could you please help me with an alternate solution for playing the sound? Thank you so much in advance! It would be nice if you also came up with some suggestions on how i can improve my code. Take a look at my code here: package com.mycompany.mygame; import java.util.ArrayList; import android.content.Context; import android.content.Intent; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.Paint; import android.media.MediaPlayer; import android.os.Handler; import android.os.Message; import android.util.Log; import android.view.Menu; import android.view.MenuInflater; import android.view.MenuItem; import android.view.MotionEvent; import android.view.SurfaceHolder; import android.view.SurfaceView; import android.view.View; import android.webkit.WebView; import android.widget.TextView; import android.widget.Toast; public class ExampleView extends SurfaceView implements SurfaceHolder.Callback { class ExampleThread extends Thread { private ArrayList<Parachuter> parachuters; private Bitmap parachuter; private Bitmap background; private Paint black; private boolean running; private SurfaceHolder mSurfaceHolder; private Context mContext; private Context mContext1; private Handler mHandler; private Handler mHandler1; private GameScreenActivity mActivity; private long frameRate; private boolean loading; public float x; public float y; public float x1; public float y1; public MediaPlayer mp1; public MediaPlayer mp2; public int parachuterIndexToResetAndDelete; public int canvasGetWidth; public int canvasGetWidth1; public int canvasGetHeight; public int livesLeftValue; public int levelValue = 1; public int levelValue1; public int parachutersDown; public int difficultySet; public boolean isSpecialAttackAvailible; public ExampleThread(SurfaceHolder sHolder, Context context, Handler handler) { mSurfaceHolder = sHolder; mHandler = handler; mHandler1 = handler; mContext = context; mActivity = (GameScreenActivity) context; parachuters = new ArrayList<Parachuter>(); parachuter = BitmapFactory.decodeResource(getResources(), R.drawable.parachuteman); black = new Paint(); black.setStyle(Paint.Style.FILL); black.setColor(Color.GRAY); background = BitmapFactory.decodeResource(getResources(), R.drawable.gamescreenbackground); running = true; // This equates to 26 frames per second. frameRate = (long) (1000 / 26); loading = true; mp1 = MediaPlayer.create(getContext(), R.raw.bombsound); } @Override public void run() { while (running) { Canvas c = null; try { c = mSurfaceHolder.lockCanvas(); synchronized (mSurfaceHolder) { long start = System.currentTimeMillis(); doDraw(c); long diff = System.currentTimeMillis() - start; if (diff < frameRate) Thread.sleep(frameRate - diff); } } catch (InterruptedException e) { } finally { if (c != null) { mSurfaceHolder.unlockCanvasAndPost(c); } } } } protected void doDraw(Canvas canvas) { canvas.drawRect(0, 0, canvas.getWidth(), canvas.getHeight(), black); //Draw for (int i = 0; i < parachuters.size(); i++) { canvas.drawBitmap(parachuter, parachuters.get(i).getX(), parachuters.get(i).getY(), null); parachuters.get(i).tick(); } //Remove for (int i = 0; i < parachuters.size(); i++) { if (parachuters.get(i).getY() > canvas.getHeight()) { parachuters.remove(i); onPlaySound(); checkLivesLeftValue(); checkAmountOfParachuters(); } else if(parachuters.get(i).isTouched()) { parachuters.remove(i); } else{ //Do nothing } } } public void loadBackground(Canvas canvas) { //Load background canvas.drawBitmap(background, 0, 0, black); } public void checkAmountOfParachuters() { mHandler.post(new Runnable() { @Override public void run() { if(parachuters.isEmpty()) { levelValue = levelValue + 1; Toast.makeText(getContext(), "New level! " + levelValue, 15).show(); if (levelValue == 3) { drawParachutersGroup1(); drawParachutersGroup2(); drawParachutersGroup3(); drawParachutersGroup4(); } else if (levelValue == 5) { drawParachutersGroup1(); drawParachutersGroup2(); drawParachutersGroup3(); drawParachutersGroup4(); drawParachutersGroup5(); } else if (levelValue == 7) { drawParachutersGroup1(); drawParachutersGroup2(); drawParachutersGroup3(); drawParachutersGroup4(); drawParachutersGroup5(); drawParachutersGroup6(); } else if (levelValue == 9) { //Draw 7 groups of parachuters drawParachutersGroup1(); drawParachutersGroup2(); drawParachutersGroup3(); drawParachutersGroup4(); drawParachutersGroup5(); drawParachutersGroup6(); drawParachutersGroup1(); } else if (levelValue > 9) { //Draw 7 groups of parachuters drawParachutersGroup1(); drawParachutersGroup2(); drawParachutersGroup3(); drawParachutersGroup4(); drawParachutersGroup5(); drawParachutersGroup6(); drawParachutersGroup1(); } else { //Draw normal 3 groups of parachuters drawParachutersGroup1(); drawParachutersGroup2(); drawParachutersGroup3(); } } else { //Do nothing } } }); } private void checkLivesLeftValue() { mHandler.post(new Runnable() { @Override public void run() { Log.d("checkLivesLeftValue", "lives = " + livesLeftValue); // TODO Auto-generated method stub if (livesLeftValue == 3) { //Message to display: "You lost! Log.d("checkLivesLeftValue", "calling onMethod now"); parachuters.removeAll(parachuters); onMethod(); } else if (livesLeftValue == 2) { Toast.makeText(getContext(), "Lives left=1", 15).show(); livesLeftValue = livesLeftValue + 1; Log.d("checkLivesLeftValue", "increased lives to " + livesLeftValue); } else if (livesLeftValue == 1) { Toast.makeText(getContext(), "Lives left=2", 15).show(); livesLeftValue = livesLeftValue + 1; Log.d("checkLivesLeftValue", "increased lives to " + livesLeftValue); } else { //Set livesLeftValueText 3 Toast.makeText(getContext(), "Lives left=3", 15).show(); livesLeftValue = livesLeftValue + 1; Log.d("checkLivesLeftValue", "increased lives to " + livesLeftValue); } } }); } public void onMethod() { mHandler.post(new Runnable() { @Override public void run() { try { Toast.makeText(getContext(), "You lost!", 15).show(); livesLeftValue = 0; //Tell the user that he lost: android.content.Context ctx = mContext; Intent i = new Intent(ctx, playerLostMessageActivity.class); i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK); i.putExtra("KEY","You got to level " + levelValue + " And you shot down " + parachutersDown + " parachuters"); i.putExtra("levelValue", levelValue); ctx.startActivity(i); System.exit(0); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); //Exit activity and start playerLostMessageActivity Toast.makeText(getContext(), "You lost!", 15).show(); livesLeftValue = 0; //Tell the user that he lost: android.content.Context ctx = mContext; Intent i = new Intent(ctx, playerLostMessageActivity.class); i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK); i.putExtra("KEY","You got to level " + levelValue + " And you shot down " + parachutersDown + " parachuters"); i.putExtra("levelValue", levelValue); System.exit(0); ctx.startActivity(i); System.exit(0); } } }); } public void onPlaySound() { try { mp1.start(); } catch (Exception e) { e.printStackTrace(); mp1.release(); } } public void onDestroy() { try { parachuters.removeAll(parachuters); mp1.stop(); mp1.release(); } catch (Exception e) { e.printStackTrace(); } } public void onPlaySound1() { try { mp2 = MediaPlayer.create(getContext(), R.raw.airriflesoundeffect); mp2.start(); } catch (Exception e) { e.printStackTrace(); mp2.release(); } } public boolean onTouchEvent(MotionEvent event) { if (event.getAction() != MotionEvent.ACTION_DOWN) releaseMediaPlayer(); x1 = event.getX(); y1 = event.getY(); checkAmountOfParachuters(); removeParachuter(); return false; } public void releaseMediaPlayer() { try { mp1.release(); } catch (Exception e) { e.printStackTrace(); } } public void removeParachuter() { try { for (Parachuter p: parachuters) { if (x1 > p.getX() && x1 < p.getX() + parachuter.getWidth() && y1 > p.getY() && y1 < p.getY() + parachuter.getHeight()) { p.setTouched(true); onPlaySound1(); parachutersDown = parachutersDown + 1; p.setTouched(false); } } } catch (Exception e) { e.printStackTrace(); } } public void initiateDrawParachuters() { drawParachutersGroup1(); } public void drawParachutersGroup1() { // TODO Auto-generated method stub //Parachuter group nr. 1 //Parachuter nr. 2 x = 75; y = 77; Parachuter p1 = new Parachuter(x, y); parachuters.add(p1); //Parachuter nr.1 x = 14; y = 28; Parachuter p = new Parachuter(x, y); parachuters.add(p); //Parachuter nr. 3 x = 250; y = 94; Parachuter p3 = new Parachuter(x, y); parachuters.add(p3); //Parachuter nr. 3 x = 275; y = 80; Parachuter p2 = new Parachuter(x, y); parachuters.add(p2); //Parachuter nr. 5 x = 280; y = 163; Parachuter p5 = new Parachuter(x, y); parachuters.add(p5); x = 125; y = 118; Parachuter p4 = new Parachuter(x, y); parachuters.add(p4); //Parachuter nr. 7 x = 126; y = 247; Parachuter p7 = new Parachuter(x, y); parachuters.add(p7); //Parachuter nr. 6 x = 123; y = 77; Parachuter p6 = new Parachuter(x, y); parachuters.add(p6); } public void drawParachutersGroup2() { // TODO Auto-generated method stub //Parachuter group nr. 2 //Parachuter nr. 5 x = 153; y = 166; Parachuter p5 = new Parachuter(x, y); parachuters.add(p5); x = 133; y = 123; Parachuter p4 = new Parachuter(x, y); parachuters.add(p4); //Parachuter nr. 7 x = 170; y = 213; Parachuter p7 = new Parachuter(x, y); parachuters.add(p7); //Parachuter nr. 6 x = 190; y = 121; Parachuter p6 = new Parachuter(x, y); parachuters.add(p6); } public void drawParachutersGroup3() { // TODO Auto-generated method stub //Parachuter group nr. 3 //Parachuter nr. 2 x = 267; y = 115; Parachuter p1 = new Parachuter(x, y); parachuters.add(p1); //Parachuter nr.1 x = 255; y = 183; Parachuter p = new Parachuter(x, y); parachuters.add(p); //Parachuter nr. 3 x = 170; y = 280; Parachuter p3 = new Parachuter(x, y); parachuters.add(p3); //Parachuter nr. 3 x = 116; y = 80; Parachuter p2 = new Parachuter(x, y); parachuters.add(p2); //Parachuter nr. 5 x = 67; y = 112; Parachuter p5 = new Parachuter(x, y); parachuters.add(p5); x = 260; y = 89; Parachuter p4 = new Parachuter(x, y); parachuters.add(p4); //Parachuter nr. 7 x = 260; y = 113; Parachuter p7 = new Parachuter(x, y); parachuters.add(p7); //Parachuter nr. 6 x = 178; y = 25; Parachuter p6 = new Parachuter(x, y); parachuters.add(p6); } public void drawParachutersGroup4() { // TODO Auto-generated method stub //Parachuter group nr. 1 //Parachuter nr. 2 x = 75; y = 166; Parachuter p1 = new Parachuter(x, y); parachuters.add(p1); //Parachuter nr.1 x = 118; y = 94; Parachuter p = new Parachuter(x, y); parachuters.add(p); //Parachuter nr. 3 x = 38; y = 55; Parachuter p3 = new Parachuter(x, y); parachuters.add(p3); //Parachuter nr. 3 x = 57; y = 18; Parachuter p2 = new Parachuter(x, y); parachuters.add(p2); //Parachuter nr. 5 x = 67; y = 119; Parachuter p5 = new Parachuter(x, y); parachuters.add(p5); x = 217; y = 113; Parachuter p4 = new Parachuter(x, y); parachuters.add(p4); //Parachuter nr. 7 x = 245; y = 234; Parachuter p7 = new Parachuter(x, y); parachuters.add(p7); //Parachuter nr. 6 x = 239; y = 44; Parachuter p6 = new Parachuter(x, y); parachuters.add(p6); } public void drawParachutersGroup5() { // TODO Auto-generated method stub //Parachuter group nr. 1 //Parachuter nr. 2 x = 59; y = 120; Parachuter p1 = new Parachuter(x, y); parachuters.add(p1); //Parachuter nr.1 x = 210; y = 169; Parachuter p = new Parachuter(x, y); parachuters.add(p); //Parachuter nr. 3 x = 199; y = 138; Parachuter p3 = new Parachuter(x, y); parachuters.add(p3); //Parachuter nr. 3 x = 22; y = 307; Parachuter p2 = new Parachuter(x, y); parachuters.add(p2); //Parachuter nr. 5 x = 195; y = 22; Parachuter p5 = new Parachuter(x, y); parachuters.add(p5); x = 157; y = 132; Parachuter p4 = new Parachuter(x, y); parachuters.add(p4); //Parachuter nr. 7 x = 150; y = 183; Parachuter p7 = new Parachuter(x, y); parachuters.add(p7); //Parachuter nr. 6 x = 130; y = 20; Parachuter p6 = new Parachuter(x, y); parachuters.add(p6); } public void drawParachutersGroup6() { // TODO Auto-generated method stub //Parachuter group nr. 1 //Parachuter nr. 2 x = 10; y = 10; Parachuter p1 = new Parachuter(x, y); parachuters.add(p1); //Parachuter nr.1 x = 20; y = 20; Parachuter p = new Parachuter(x, y); parachuters.add(p); //Parachuter nr. 3 x = 30; y = 30; Parachuter p3 = new Parachuter(x, y); parachuters.add(p3); //Parachuter nr. 3 x = 60; y = 60; Parachuter p2 = new Parachuter(x, y); parachuters.add(p2); //Parachuter nr. 5 x = 90; y = 90; Parachuter p5 = new Parachuter(x, y); parachuters.add(p5); x = 120; y = 120; Parachuter p4 = new Parachuter(x, y); parachuters.add(p4); //Parachuter nr. 7 x = 150; y = 150; Parachuter p7 = new Parachuter(x, y); parachuters.add(p7); //Parachuter nr. 6 x = 180; y = 180; Parachuter p6 = new Parachuter(x, y); parachuters.add(p6); } public void drawParachuters() { Parachuter p = new Parachuter(x, y); parachuters.add(p); Toast.makeText(getContext(), "x=" + x + " y=" + y, 15).show(); } public void setRunning(boolean bRun) { running = bRun; } public boolean getRunning() { return running; } } /** Handle to the application context, used to e.g. fetch Drawables. */ private Context mContext; /** Pointer to the text view to display "Paused.." etc. */ private TextView mStatusText; /** The thread that actually draws the animation */ private ExampleThread eThread; public ExampleView(Context context) { super(context); // register our interest in hearing about changes to our surface SurfaceHolder holder = getHolder(); holder.addCallback(this); // create thread only; it's started in surfaceCreated() eThread = new ExampleThread(holder, context, new Handler() { @Override public void handleMessage(Message m) { // mStatusText.setVisibility(m.getData().getInt("viz")); // mStatusText.setText(m.getData().getString("text")); } }); setFocusable(true); } @Override public boolean onTouchEvent(MotionEvent event) { return eThread.onTouchEvent(event); } public ExampleThread getThread() { return eThread; } @Override public void surfaceChanged(SurfaceHolder arg0, int arg1, int arg2, int arg3) { // TODO Auto-generated method stub } public void surfaceCreated(SurfaceHolder holder) { if (eThread.getState() == Thread.State.TERMINATED) { eThread = new ExampleThread(getHolder(), getContext(), getHandler()); eThread.start(); } else { eThread.start(); } } @Override public void surfaceDestroyed(SurfaceHolder holder) { boolean retry = true; eThread.setRunning(false); while (retry) { try { eThread.join(); retry = false; } catch (InterruptedException e) { } } } }

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  • Referencing outer query's tables in a subquery

    - by soulmerge
    Is it possible to reference an outer query in a subquery with MySQL? I know there are some cases where this is possible: SELECT * FROM table t1 WHERE t1.date = ( SELECT MAX(date) FROM table t2 WHERE t2.id = t1.id)` ); But I'm wondering if something like this could work: SELECT u.username, c._postCount FROM User u INNER JOIN ( SELECT p.user, COUNT(*) AS _postCount FROM Posting p --# This is the reference I would need: WHERE p.user = u.id ) c ON c.user = u.id WHERE u.joinDate < '2009-10-10'; I know I could achieve the same using a GROUP BY or by pulling the outer WHERE clause into the sub-query, but I need this for automatic SQL generation and cannot use either alternative for various other reasons.

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  • MySQL Query involving column names containing math operators

    - by devil_fingers
    I'm a MySQL scrub, and I have asked around and checked around the internet for what I'm sure will turn out to be something obvious, but I'm very frustrated with what I thought would be a very, very simple query not working. So here goes. Please be gentle. Basically, in a large database, some of the column names contain mathematical operators like "/" and "+." (Don't ask, it's not my database, I can't do anything about it). Here is the "essence" of my query (I took out the irrelevant stuff for the sake of this question): SELECT PlayerId, Season, WPA/LI AS WPALI FROM tht.stats_batting_master WHERE Season = "2010" AND teamid > 0 AND PA >= 502 GROUP BY playerid ORDER BY WPALI DESC When I run this, it returns "Unknown column 'LI' in 'field list'," I assume because it sees the "/" in WPA/LI as a division sign. Like I said, I'm sure this is easy enough to work around (it must be given how much this database is used), but I haven't' been able to figure out how. Thanks in advance for any help.

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  • Help me write a nicer SQL query in Rails

    - by Sainath Mallidi
    Hi, I am trying to write an SQL query to update some of the attributes that are regularly pulled from source. the output will be a text file with the following fields: author, title, date, popularity I have two tables to update one is the author information and the other is popularity table. And the Author Active Record object has one popularity. Currently I'm doing it like this.\ arr.each { |x| x = x.split(" ") results = Author.find_by_sql("SELECT authors.id FROM authors, priorities WHERE authors.id=popularity.authors_id AND authors.author = x[0]") results[0].popularity.update_attribute("popularity", x[3]) I need two tables because the popularity keeps changing, and I need only the top 1000 popular ones, but I still need to keep the previously popular ones also. Is there any nicer way to do this, instead of one query for every new object. Thanks.

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  • sql query where parameters null not null

    - by Laziale
    I am trying to do a sql query and to build the where condition dynamically depending if the parameters are null or no. I have something like this: SELECT tblOrder.ProdOrder, tblOrder.Customer FROM tblOrder CASE WHEN @OrderId IS NOT NULL THEN WHERE tblOrder.OrderId = @OrderId ELSE END CASE WHEN @OrderCustomer IS NOT NULL THEN AND tblOrder.OrderCustomer = @OrderCustomer ELSE END END This doesn't work, but this is just a small prototype how to assemble the query, so if the orderid is not null include in the where clause, or if the ordercustomer is not null include in the where clause. But I see problem here, for example if the ordercustomer is not null but the orderid is null, there will be error because the where keyword is not included. Any advice how I can tackle this problem. Thanks in advance, Laziale

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  • Adding a Third Table to a Two-Table Join Query

    - by John
    Hello, The query below works just fine. It pulls fields from two MySQL tables, "comment" and "login". It does this for rows where "username" in the table "login" equals the variable "$profile." It also pulls fields for rows where "loginid" in the table "comment" equals the "loginid" that is also being pulled from "login." I would like to pull data from a third table called "submission," which has the following fields: submissionid loginid title url displayurl datesubmitted I would like to pull fields from rows in "submission" where "loginid" equals the "loginid" that is already being pulled from the other two tables, "login" and "comment." How can I do this? Thanks in advance, John Query: $sqlStrc = "SELECT l.username, l.loginid, c.loginid, c.commentid, c.submissionid, c.comment, c.datecommented FROM comment AS c INNER JOIN login AS l ON c.loginid = l.loginid WHERE l.username = '$profile' ORDER BY c.datecommented DESC LIMIT 10";

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  • NoSQL for concurrent reads/writes

    - by Mickael Marrache
    After getting some performance issues for an application using a MySQL database, I'm thinking of using NoSQL solutions. My architecture is as follows: One application receives messages from the network at a high throughput (i.e. 50000 messages/sec). Each message is stored in the DB, so it's important for the write rate to be as fast as the arrival rate. Then, I also have some PHP pages that accesses the DB to get the data stored by the other application. It's important for me that the retrieved data is as relevant as possible (i.e. not old data, let's say not more than 5 seconds old). Also, the data is not critical, so I don't need any security mechanism to avoid losing the data. I see there are a lot of NoSQL solutions, but I don't know if they are all relevant. Could you please provide me some directions. Thanks

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  • JQuery Optimization: Is there any way to speed up the rendering of the FlexSelect control?

    - by Sephrial
    Greetings, I am new to jQuery, and I have a performance problem with the FlexSelect control where it takes about 5 seconds to render the dropdown control (in the renderDropdown() function). The dropdown list contains about 5000 element. I believe all the runtime is attributed to the following block of code: var list = this.dropdownList.html(""); $.each(this.results, function() { list.append($("<li/>").html(this.name)); }); Question: Are there any alternatives that would build this list of elements in a more inefficient manner?

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  • Command Query Separation validating for retries

    - by Neil Barnwell
    So I'm comfortable with the basic concept of CQS, where you might have a command that writes to one database, and that updates the query database that you read from. However, consider the scenario where you are entering data, and want to prevent duplicates. Using new employee data entry an employee register as an example, working through a pile of application forms to key in the new employees' details: Take top sheet. Key in employee name and unique payroll number to UI. Submit. Put paper in "completed pile". Repeat. How would you now prevent the user from keying in the same payroll number again, say for instance if they get distracted and can't remember whether they've keyed one in already and the "message" hasn't got all the way back to the query db for the user to search?

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  • Adding more namespace in the code file affects performace ?

    - by Harikrishna
    If we imports more namespace in the code file(cs file) then it affects on perfomance ? Like we should add namespace in the cs file as needed. That is adding more namespace in the cs file affects performance ? Like using System; using System.Data.Sql; using System.Collections.Generic; using System.Data; using System.IO; using System.Linq; using System.Text.RegularExpressions; using System.Windows.Forms; using System.Xml; using System.Data.SqlClient; using System.ComponentModel;

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  • SQL query to select distinct record with 2 or more repetition in another field

    - by kyohiros
    So I have this table of book orders, it contains 2 columns, one is the order ID(primary key) and another is the ID of the book that the customer ordered. For example: | OrderID | BookID | | 0001 | B002 | | 0002 | B005 | | 0003 | B002 | | 0004 | B003 | | 0005 | B005 | | 0006 | B002 | | 0007 | B002 | What I want is to get the IDs of the books that got 2 or more purchases/orders, for example if I run the SQL query against the above data, I would get this as the result: | BookID | | B002 | | B005 | I don't know if this can be archived in SQL or I have to built a simpler statement and repetitive run the query against all the records in another language. I need some help and thanks for reading my question.

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