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• JVM tuning on Amazon EC2

  - by Shadowman

  We will be deploying a production application to Amazon EC2 very shortly. Initially, we'll just be using a "small" instance, but have plans to scale up not long afterwards. My question is, has any investigation been done on JVM tuning for the EC2 environment? Are there any specific changes that we should make to our JVM parameters to compensate for quirks/characteristics of Amazon EC2? Or, do the normal tuning methodologies apply here as they would in a physical environment? Our application will be deployed on Tomcat 6.x. It is built using JBoss Seam 2.2.x, and uses PostgreSQL 8.x as the backend database. Any advice you can give is greatly appreciated!

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• Create MySQL user and database from PHP

  - by snaken

  Hi, Is there a way to create a new MySQL database, a new MySQL user and give the new user priviledges on the new database all using PHP? I've seen examples where mysql_query is used like this: mysql_query("CREATE DATABASE ".$dbname)or die(mysql_error()); but i don't see how this would work as there's no database connection. Help please!

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• Trying to display text from mysql field starting 30 words into paragraph?

  - by brandon

  I can't figure this out for the life of me... Using wordpress trying to display excerpt from posts starting 30 words in.. php mysql Please help!

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• Hanging Forms When I Drag And Move My Forms

  - by hosseinsinohe

  I Write a Windows Application By C Sharp. I Use a Picture in Background of my Form (MainForm) And I Use Many Picture in Buttons in This Form,And also I Use Some Panel And Label with Transparent Background Color. My Forms,Panels And Buttons has flicker. I solve this problem by a method in this thread. But Still when other Forms Start over this Form,my Forms hangs when I Drag and Move my Forms over this Form.How can I Solve this Problem to Move And Drags my Forms easily And Speed? Edit:: My Forms Load Data From Access 2007 DataBase file.I Use Datasets,DataGridViews And Other Components to Load And show Data in My Forms.

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• SQL select statement from 2 tables

  - by Steven

  Hi, I have a small sql question. I have 2 tables Members and Managers Members has: memberID, Name, Address Managers has: memberID, EditRights, DeleteRights EditRights and DeleteRights are of type bit. Mangers have a relationship with Members, because they are members themselves. I want to select all members id's, name and adress and for the members that are managers show if they have editrights and/or deleterights. SO: Exmaple data Members: ID, Name, Address 1, tom, 2 flat 2, dan, 3 flat 3, ben, 4 flat 4, bob, 6 flat 5, sam, 9 flat Managers: ID, Editrights, deleterights 2, 0, 1 4, 1, 1 5, 0, 0 I would like to display a select like this: 1, tom, 2 flat, no rights 2, dan, 3 flat, Delete 3, ben, 4 flat, no rights 4, bob, 6 flat, Edit&Delete 5, sam, 9 flat, no rights Any help would be great

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• Fast read of certain bytes of multiple files in C/C++

  - by Alejandro Cámara

  I've been searching in the web about this question and although there are many similar questions about read/write in C/C++, I haven't found about this specific task. I want to be able to read from multiple files (256x256 files) only sizeof(double) bytes located in a certain position of each file. Right now my solution is, for each file: Open the file (read, binary mode): fstream fTest("current_file", ios_base::out | ios_base::binary); Seek the position I want to read: fTest.seekg(position*sizeof(test_value), ios_base::beg); Read the bytes: fTest.read((char *) &(output[i][j]), sizeof(test_value)); And close the file: fTest.close(); This takes about 350 ms to run inside a for{ for {} } structure with 256x256 iterations (one for each file). Q: Do you think there is a better way to implement this operation? How would you do it?

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• can we use join inside join in mysql?

  - by I Like PHP

  i have 3 tables structure is below tbl_login login_id | login_name 1 | keshav tbl_role role_id | login_id( refer to tbl_login.login_id) 1 | 1 tbl_stuff stuff_id | role_id( refer to tbl_role.role_id) 1 | 1 i need data in follow format stuff_id | login_name 1 | keshav how to use JOIN to retrive the above data in mysql?

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• Any disadvantages to this tagging approach

  - by donpal

  I have a table of tags ID tag --- ------ 1 tagt 2 tagb 3 tagz 4 tagn In my items table, I'm using those tags in serialized format, comma delimited ID field1 tags ---- ------ ----- 1 value1 tagt,tagb 2 value2 tagb 3 value3 tagb,tagn 4 value4 When I need to find items that have this tag, I plan to deserialize the tags. But I'm not actually sure how to do it, and if it's better to have a third table for associations instead between the tags and the items.

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• Advanced SQL query with lots of joins

  - by lund.mikkel

  Hey fellow programmers Okay, first let me say that this is a hard one. I know the presentation may be a little long. But I how you'll bare with me and help me through anyway :D So I'm developing on an advanced search for bicycles. I've got a lot of tables I need to join to find all, let's say, red and brown bikes. One bike may come in more then one color! I've made this query for now: SELECT DISTINCT p.products_id, #simple product id products_name, #product name products_attributes_id, #color id pov.products_options_values_name #color name FROM products p LEFT JOIN products_description pd ON p.products_id = pd.products_id INNER JOIN products_attributes pa ON pa.products_id = p.products_id LEFT JOIN products_options_values pov ON pov.products_options_values_id = pa.options_values_id LEFT JOIN products_options_search pos ON pov.products_options_values_id = pos.products_options_values_id WHERE pos.products_options_search_id = 4 #code for red OR pos.products_options_search_id = 5 #code for brown My first concern is the many joins. The Products table mainly holds product id and it's image and the Products Description table holds more descriptive info such as name (and product ID of course). I then have the Products Options Values table which holds all the colors and their IDs. Products Options Search is containing the color IDs along with a color group ID (products_options_search_id). Red has the color group code 4 (brown is 5). The products and colors have a many-to-many relationship managed inside Products Attributes. So my question is first of all: Is it okay to make so many joins? Is i hurting the performance? Second: If a bike comes in both red and brown, it'll show up twice even though I use SELECT DISTINCT. Think this is because of the INNER JOIN. Is this possible to avoid and do I have to remove the doubles in my PHP code? Third: Bikes can be double colored (i.e. black and blue). This means that there are two rows for that bike. One where it says the color is black and one where is says its blue. (See second question). But if I replace the OR in the WHERE clause it removes both rows, because none of them fulfill the conditions - only the product. What is the workaround for that? I really hope you will and can help me. I'm a little desperate right now :D Regards Mikkel Lund

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• Tricking the server to load files faster?

  - by Yongho

  If we have a website with multiple images and videos, I've read that it's best to serve them from other domains so that the browser can simultaneously download a bunch of files, rather than waiting one by one for each file to be downloaded. For example, if we have a website http://example.com/, we might consider serving: Videos from http://video.example.com/ Images from http://images.example.com/ etc. Question: can we achieve the simultaneous downloading by tricking the browser into believing that the files are hosted there, or do they actually need to be at that location? We can, for example, pretend to serve video from http://video.example.com/ when actually it's just a clever htaccess rewrite that ACTUALLY serves from http://example.com/video.php. In this case, the video is being served from the main domain but because we refer it as http://video.example.com/, it may think that it's another domain and thus load files simultaneously, rather than one by one. Is this feasible?

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• C# DynamicMethod prelink

  - by soywiz

  I'm the author of a psp emulator made in C#. I'm generating lots of "DynamicMethod" using ILGenerator. I'm converting assembly code into an AST, and then generating IL code and building that DynamicMethod. I'm doing this in another thread, so I can generate new methods while the program is executing others so it can run smoothly. My problem is that the native code generation is lazy, so the machine code is generated when the function is called, not when the IL is generated. So it generates in the program executing thread, native code generation is prettly slow as it is the asm-ast-il step. I have tried the Marshal.Prelink method that it is suposed to generate the machine code before executing the function. It does work on Mono, but it doesn't work on MS .NET. Marshal.Prelink(MethodInfo); Is there a way of prelinking a DynamicMethod on MS .NET? I thought adding a boolean parameter to the function that if set, exits the function immediately so no code is actually executed. I could "prelink" that way, but I think that's a nasty solution I want to avoid. Any idea?

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• Correlate GROUP BY and LEFT JOIN on multiple criteria to show latest record?

  - by Sunbird

  In a simple stock management database, quantity of new stock is added and shipped until quantity reaches zero. Each stock movement is assigned a reference, only the latest reference is used. In the example provided, the latest references are never shown, the stock ID's 1,4 should have references charlie, foxtrot respectively, but instead show alpha, delta. How can a GROUP BY and LEFT JOIN on multiple criteria be correlated to show the latest record? http://sqlfiddle.com/#!2/6bf37/107 CREATE TABLE stock ( id tinyint PRIMARY KEY, quantity int, parent_id tinyint ); CREATE TABLE stock_reference ( id tinyint PRIMARY KEY, stock_id tinyint, stock_reference_type_id tinyint, reference varchar(50) ); CREATE TABLE stock_reference_type ( id tinyint PRIMARY KEY, name varchar(50) ); INSERT INTO stock VALUES (1, 10, 1), (2, -5, 1), (3, -5, 1), (4, 20, 4), (5, -10, 4), (6, -5, 4); INSERT INTO stock_reference VALUES (1, 1, 1, 'Alpha'), (2, 2, 1, 'Beta'), (3, 3, 1, 'Charlie'), (4, 4, 1, 'Delta'), (5, 5, 1, 'Echo'), (6, 6, 1, 'Foxtrot'); INSERT INTO stock_reference_type VALUES (1, 'Customer Reference'); SELECT stock.id, SUM(stock.quantity) as quantity, customer.reference FROM stock LEFT JOIN stock_reference AS customer ON stock.id = customer.stock_id AND stock_reference_type_id = 1 GROUP BY stock.parent_id

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• What's the quickest way to remove an element from a Map by value in Java?

  - by Supertux

  What's the quickest way to remove an element from a Map by value in Java? Currently I'm using: DomainObj valueToRemove = new DomainObj(); String removalKey = null; for (Map.Entry<String, DomainObj> entry : map.entrySet()) { if (valueToRemove.equals(entry.getValue())) { removalKey = entry.getKey(); break; } } if (removalKey != null) { map.remove(removalKey); }

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• Does the order of columns matter in a group by clause?

  - by Jeff Meatball Yang

  If I have two columns, one with very high cardinality and one with very low cardinality (unique # of values), does it matter in which order I group by? Here's an example: select dimensionName, dimensionCategory, sum(someFact) from SomeFact f join SomeDim d on f.dimensionKey = d.dimensionKey group by d.dimensionName, -- large number of unique values d.dimensionCategory -- small number of unique values Are there situations where it matters?

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• MySQL, Implementing a ViewCount that automatically add +1 every time

  - by nobosh

  I'm MySQL, I have a table full of docs. Each row represents a doc. I'd like to have a data column for "VIEWS" that automatically adds +1 every time the row is accessed and avoid needing to write a SQL UPDATE that hits the DB after the SELECT to get the doc in the web app. Any smart clever ways to solve for this? Thanks

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• mysql display each day in a month

  - by Jason

  during a month, display the infor each date, order by date, but this infor is empty in some day. how can i still display each day as a row? Product date ----------------- 20 2008-01-01 10 2008-01-02 20 2008-01-03 10 2008-01-05 09 2008-01-08 30 2008-01-09 result: Product date ----------------- 20 2008-01-01 10 2008-01-02 20 2008-01-03 0 2008-01-04 10 2008-01-05 0 2008-01-06 0 2008-01-07 09 2008-01-08 30 2008-01-09

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• WCF high instance count: anyone knows negative sideffects?

  - by Alex

  Hi there! Did anyone experience or know of negative side effects from having a high service instance count like 60k? Aside from the memory consumption of course. I am planning to increase the threshold for the maximum allowed instance count in our production environments. I am basically sick of severe production incidents just because "something" forgot to close a proxy properly. I plan to go to something like 60k instances which will allow the service to survive using default session timeouts at a call rate average for our clients. Thanks, Alex

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• WordPress: Prevent Showing of Sub Category Posts

  - by Carlos Pattrezzi

  Hi, I'd like to know how to prevent showing of sub-category posts. My home page lists all posts from three "main categories" (parent category), but unfortunately it's also listing some posts from the sub-categories. Here's the code that I'm using to get the posts from specific category: <h2>Category Name</h2> <ul> <?php $category_query = new WP_Query(array('category_name' => 'category1', 'showposts' => 5)); ?> <?php while ($profissionais_query->have_posts()) : $profissionais_query->the_post(); ?> <li> <a class="title" href="<?php the_permalink(); ?>"><?php the_title(); ?></a> <?php the_excerpt(); ?> </li> <?php endwhile; ?> </ul> Does anyone have an idea? Thank you.

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• Unknown column even thoug it exits

  - by george

  I have SELECT servisler.geo_location, servisler.ADRES_MERKEZ, servisler.ADRES_ILCE, servisler.ADRES_IL, servisler.FIRMA_UNVANI, servisler.ADRES_ISTEL, servisler.YETKILI_ADISOYADI, urun_gruplari.GRUP_ADI FROM servisler INNER JOIN urun_gruplari ON kullanici_cihaz.URUN_GRUP_NO= urun_gruplari.RECNO INNER JOIN kullanici ON kullanici.SERVIS_RECNO = servisler.RECNO INNER JOIN kullanici_cihaz ON kullanici.RECNO = kullanici_cihaz.KUL_RECNO AND kullanici_cihaz.URUN_GRUP_NO = urun_gruplari.RECNO where kullanici.kullanici = 'MAR.EDI.003' but it says [Err] 1054 - Unknown column 'kullanici_cihaz.URUN_GRUP_NO' in 'on clause' enen though the column exits. What is its problem? schema Server version: 5.1.33-community-log

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• SQL: GROUP BY after JOIN without overriding rows?

  - by krismeld

  I have a table of basketball leagues, a table af teams and a table of players like this: LEAGUES ID | NAME | ------------------ 1 | NBA | 2 | ABA | TEAMS: ID | NAME | LEAGUE_ID ------------------------------ 20 | BULLS | 1 21 | KNICKS | 2 PLAYERS: ID | TEAM_ID | FIRST_NAME | LAST_NAME | --------------------------------------------- 1 | 21 | John | Starks | 2 | 21 | Patrick | Ewing | Given a League ID, I would like to retrieve all the players' names and their team ID from all the teams in that league, so I do this: SELECT t.id AS team_id, p.id AS player_id, p.first_name, p.last_name FROM teams AS t JOIN players AS p ON p.team_id = t.id WHERE t.league_id = 1 which returns: [0] => stdClass Object ( [team_id] => 21 [player_id] => 1 [first_name] => John [last_name] => Starks ) [1] => stdClass Object ( [team_id] => 21 [player_id] => 2 [first_name] => Patrick [last_name] => Ewing ) + around 500 more objects... Since I will use this result to populate a dropdown menu for each team containing each team's list of players, I would like to group my result by team ID, so the loop to create these dropdowns will only have to cycle through each team ID instead of all 500+ players each time. But when I use the GROUP BY like this: SELECT t.id AS team_id, p.id AS player_id, p.first_name, p.last_name FROM teams AS t JOIN players AS p ON p.team_id = t.id WHERE t.league_id = 1 GROUP BY t.id it only returns one player from each team like this, overriding all the other players on the same team because of the use of the same column names. [0] => stdClass Object ( [team_id] => 21 [player_id] => 2 [first_name] => Patrick [last_name] => Ewing ) [1] => stdClass Object ( [team_id] => 22 [player_id] => 31 [first_name] => Shawn [last_name] => Kemp ) etc... I would like to return something like this: [0] => stdClass Object ( [team_id] => 2 [player_id1] => 1 [first_name1] => John [last_name1] => Starks [player_id2] => 2 [first_name2] => Patrick [last_name2] => Ewing +10 more players from this team... ) +25 more teams... Is it possible somehow?

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• Database time data retrieval, time based queries

  - by Raphael Pineda

  I am new to time manipulation or time arithmetic operations and am currently developing a navigation system with Web server based information and currently I have this Database that contains a table peek hours whose columns are id, start_time, end_time , edge_id, day_of_the_week, edge_weight ------------------------------------------------------------------------ | Peek Hours | ------------------------------------------------------------------------ | | | | | | | | id | start_time | end_time | edge_id | day_of_the_week | edge_weight | | | | | | | | ------------------------------------------------------------------------ I am using PHP as a webservice and so based on the current time i want to get all the records that would fit this equation start_time< current_time < end_time

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• Why does dojo parsing time depend on css and images availability?

  - by Kniganapolke

  I have been profiling javascript on my page that uses dojo widgets. I don't use explicit parsing - the parser runs on page load. What I noticed is that if I clear browser cache before refreshing the page, dojo parsing takes much more time than if all the files are already cached. Note that we build all the required dojo modules into a layer (a single file), so we don't lazy-load any js files. I wonder if dojo parsing process depends on images and css resources, as far as I know it only instantiates widgets and injects dom nodes. Do you have any ideas why dojo parser runs longer (2-3 times longer in my case) when the cache is cleared?

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• How to perform COUNT() or COUNT(*)

  - by ninumedia

  I have a list of tags in a database. Ex: villan hero spiderman superman superman I wanted to obtain a sorted list of the tag names in ascending order and the number of times the unique tag appeared in the database. I wrote this code: Ex: SELECT hashtag.tag_name, COUNT( * ) AS number FROM hashtag GROUP BY hashtag.tag_name ORDER BY hashtag.tag_name ASC This yields the correct result: hero - 1 spiderman - 1 superman - 2 villan - 1 How can I obtain the full COUNT of this entire list. The answer should be 4 in this case because there are naturally 4 rows. I can't seem to get a correct COUNT() without the statement failing. Thanks so much for the help! :)

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• How to get grade A on these Yslow rules?

  - by metal-gear-solid

  Use a Content Delivery Network (CDN) Compress components with gzip Configure entity tags (ETags) Add Expires headers If i don't have access to Apache configuration.

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• PHP Object References in Frameworks

  - by bigstylee

  Before I dive into the disscusion part a quick question; Is there a method to determine if a variable is a reference to another variable/object? For example $foo = 'Hello World'; $bar = &$foo; echo (is_reference($bar) ? 'Is reference' : 'Is orginal'; I have been using PHP5 for a few years now (personal use only) and I would say I am moderately reversed on the topic of Object Orientated implementation. However the concept of Model View Controller Framework is fairly new to me. I have looked a number of tutorials and looked at some of the open source frameworks (mainly CodeIgnitor) to get a better understanding how everything fits together. I am starting to appreciate the real benefits of using this type of structure. I am used to implementing object referencing in the following technique. class Foo{ public $var = 'Hello World!'; } class Bar{ public function __construct(){ global $Foo; echo $Foo->var; } } $Foo = new Foo; $Bar = new Bar; I was surprised to see that CodeIgnitor and Yii pass referencs of objects and can be accessed via the following method: $this->load->view('argument') The immediate advantage I can see is a lot less code and more user friendly. But I do wonder if it is more efficient as these frameworks are presumably optimised? Or simply to make the code more user friendly? This was an interesting article Do not use PHP references.

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