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• Hadoop reduce task gets hung

  - by user806098

  I set up a hadoop cluster with 4 nodes, When running a map-reduce task, the map task finishes quickly, while the reduce task hangs at 27% percent. I checked the log, it's that the reduce task fails to fetch map output from map nodes. The job tracker log of master shows messages like this: 2011-06-27 19:55:14,748 INFO org.apache.hadoop.mapred.JobTracker: Adding task (REDUCE) 'attempt_201106271953_0001_r_000000_0' to tip task_201106271953_0001_r_000000, for tracker 'tracker_web30.bbn.com.cn:localhost/127.0.0.1:56476' And the name node log of master shows messages like this: 2011-06-27 14:00:52,898 INFO org.apache.hadoop.ipc.Server: IPC Server handler 4 on 54310, call register(DatanodeRegistration(202.106.199.39:50010, storageID=DS-1989397900-202.106.199.39-50010-1308723051262, infoPort=50075, ipcPort=50020)) from 192.168.225.19:16129: error: java.io.IOException: verifyNodeRegistration: unknown datanode 202.106.199.3 9:50010 However, neither the "web30.bbn.com.cn" or 202.106.199.39, 202.106.199.3 is the slave node. I think such ip/domains appear because hadoop fails to resolve a node(first in the Intranet DNS server), then it goes to a higher-level DNS server, later to the top, still fails, then the "junk" ip/domains are returned. But I checked my config, it goes like this: /etc/hosts: 127.0.0.1 localhost.localdomain localhost ::1 localhost6.localdomain6 localhost6 192.168.225.16 master 192.168.225.66 slave1 192.168.225.20 slave5 192.168.225.17 slave17 conf/core-site.xml: hadoop.tmp.dir /root/hadoop_tmp/hadoop_${user.name} fs.default.name hdfs://master:54310 io.sort.mb 1024 hdfs-site.xml: dfs.replication 3 masters: master slaves: master slave1 slave5 slave17 Also, all firewalls(iptables) are turned off, and ssh between each 2 nodes is ok. so I don't know where exact the error comes from. Please help. Thanks a lot.

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• Long running transactions with Spring and Hibernate?

  - by jimbokun

  The underlying problem I want to solve is running a task that generates several temporary tables in MySQL, which need to stay around long enough to fetch results from Java after they are created. Because of the size of the data involved, the task must be completed in batches. Each batch is a call to a stored procedure called through JDBC. The entire process can take half an hour or more for a large data set. To ensure access to the temporary tables, I run the entire task, start to finish, in a single Spring transaction with a TransactionCallbackWithoutResult. Otherwise, I could get a different connection that does not have access to the temporary tables (this would happen occasionally before I wrapped everything in a transaction). This worked fine in my development environment. However, in production I got the following exception: java.sql.SQLException: Lock wait timeout exceeded; try restarting transaction This happened when a different task tried to access some of the same tables during the execution of my long running transaction. What confuses me is that the long running transaction only inserts or updates into temporary tables. All access to non-temporary tables are selects only. From what documentation I can find, the default Spring transaction isolation level should not cause MySQL to block in this case. So my first question, is this the right approach? Can I ensure that I repeatedly get the same connection through a Hibernate template without a long running transaction? If the long running transaction approach is the correct one, what should I check in terms of isolation levels? Is my understanding correct that the default isolation level in Spring/MySQL transactions should not lock tables that are only accessed through selects? What can I do to debug which tables are causing the conflict, and prevent those tables from being locked by the transaction?

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• Concatenate CLOB-rows with PL/SQL

  - by david K

  Hi, I've got a table which has an id and a clob content like: Create Table v_example_l ( nip number, xmlcontent clob ); We insert our data: Insert into V_EXAMPLE_L (NIP,XMLCONTENT) Values (17852,'<section><block><name>delta</name><content>548484646846484</content></block></section>'); Insert into V_EXAMPLE_L (NIP,XMLCONTENT) Values (17852,'<section><block><name>omega</name><content>545648468484</content></block></section>'); Insert into V_EXAMPLE_L (NIP,XMLCONTENT) Values (17852,'<section><block><name>gamma</name><content>54564846qsdqsdqsdqsd8484</content></block></section>'); I'm trying to do a function that concatenates the rows of the clob that gone be the result of a select, i mean without having to give multiple parameter about the name of table or such, i should only give here the column that contain the clobs, and it should handle the rest. CREATE OR REPLACE function assemble_clob(q varchar2) return clob is v_clob clob; tmp_lob clob; hold VARCHAR2(4000); --cursor c2 is select xmlcontent from V_EXAMPLE_L where id=17852 cur sys_refcursor; begin OPEN cur FOR q; LOOP FETCH cur INTO tmp_lob; EXIT WHEN cur%NOTFOUND; --v_clob := v_clob || XMLTYPE.getClobVal(tmp_lob.xmlcontent); v_clob := v_clob || tmp_lob; END LOOP; return (v_clob); --return (dbms_xmlquery.getXml( dbms_xmlquery.set_context("Select 1 from dual")) ) end assemble_clob; The function is broken... (if anybody could give me a help, thanks a lot, and i'm noob in sql so ....). Thanks!

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• $.ajax not loading data data everytime from server

  - by Ted

  I have written a simple jQuery.ajax function which loads a user control from the server on click of a button. The first time I click the button, it goes to the server and gets me the user control. But each subsequent click of the same button does not goes to the server to fetch me the user control. Since my user control fetches data from db, I need to reload the user control everytime i hit the button. But if anyhow I get my user control to unload from the page, and re-click the button, it goes to the server and fetches me the user control. Here's the code: $("#btnLoad").click(function() { if ($(this).attr("value") == "Load Control") { $.ajax({ url: "AJAXHandler.ashx", data: { "lt": "loadcontrol" }, dataType: "html", success: function(data) { content.html(data); } }); $(this).attr("value", "Unload Control"); } else { $.ajax({ url: "AJAXHandler.ashx", data: { "lt": "unloadcontrol" }, dataType: "html", success: function(data) { content.html(data); } }); $(this).attr("value", "Load Control"); } }); Please let me know if there is any other way I can get my user control loaded from server everytime I click the button.

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• save html-formatted text to database

  - by yozhik

  Hi all! I want to save html-formatted text to database, but when I do that it is don't save html-symbols like < / ' and others This is how I read article from database for editing: <p class="Title">??????????? ???????:</p> <textarea name="EN" cols="90" rows="20" value="<?php echo $articleArr['EN']; ?>" ></textarea> And this is how I save it to database: function UpdateArticle($ArticleID, $ParentName, $Title, $RU, $EN, $UKR) { //fetch data from database for dropdown lists //connect to db or die) $db = mysql_connect($GLOBALS["gl_dbName"], $GLOBALS["gl_UserName"], $GLOBALS["gl_Password"] ) or die ("Unable to connect"); //to prevenr ????? symbols in unicode - utf-8 coding mysql_query("SET NAMES 'UTF8'"); mysql_set_charset('utf8'); mysql_query("SET NAMES 'utf8' COLLATE 'utf8_general_ci'"); //select database mysql_select_db($GLOBALS["gl_adminDatabase"], $db); $sql = "UPDATE Articles SET AParentName='".$ParentName."', ATitle='".$Title."', RU='".$RU."', EN='".$EN."', UKR='".$UKR."' WHERE ArticleID='".$ArticleID."';"; //execute SQL-query $result = mysql_query($sql, $db); if (!$result) { die('Invalid query: ' . mysql_error()); } //close database = very inportant mysql_close($db); } Help me please, how can I save such texts properly, Thanx!

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• Do complex JOINs cause high coupling and maintenance problems ?

  - by ashkan.kh.nazary

  Our project has ~40 tables with complex relations.A colleague believes in using long join queries which enforces me to learn about tables outside of my module but I think I should not concern about tables not directly related to my module and use data access functions (written by those responsible for other modules) when I need data from them. Let me clarify: I am responsible for the ContactVendor module which enables the customers to contact the vendor and start a conversation about some specific product. Products module has it's own complex tables and relations with functions that encapsulate details (for example i18n, activation, product availability etc ...). Now I need to show the product title of some product related to some conversation between the vendor and customers. I may either write a long query that retrieves the product info along with conversation stuff in one shot (which enforces me to learn about Product tables) OR I may pass the relevant product_id to the get_product_info(int) function. First approach is obviously demanding and introduces many bad practices and things I normally consider fault in programming. The problem with the second approach seems to be the countless mini queries these access functions cause and performance loss is a concern when a loop tries to fetch product titles for 100 products using functions that each perform a separate query. So I'm stuck between "don't code to the implementation, code to interface" and performance. What is the right way of doing things ? UPDATE: I'm specially concerned about possible future modifications to those tables outside of my module. What if the Products module decided to change the way they are doing things? or for some reason modify the schema? It means some other modules would break or malfunction until the change is integrated to them. The usual ripple effect problem.

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• rest and client rights integration, and backbone.js

  - by Francois

  I started to be more and more interested in the REST architecture style and client side development and I was thinking of using backbone.js on the client and a REST API (using ASP.NET Web API) for a little meeting management application. One of my requirements is that users with admin rights can edit meetings and other user can only see them. I was then wondering how to integrate the current user rights in the response for a given resource? My problem is beyond knowing if a user is authenticated or not, I want to know if I need to render the little 'edit' button next to the meeting (let's say I'm listing the current meetings in a grid) or not. Let's say I'm GETing /api/meetings and this is returning a list of meetings with their respective individual URI. How can I add if the user is able to edit this resource or not? This is an interesting passage from one of Roy's blog posts: A REST API should be entered with no prior knowledge beyond the initial URI (bookmark) and set of standardized media types that are appropriate for the intended audience (i.e., expected to be understood by any client that might use the API). From that point on, all application state transitions must be driven by client selection of server-provided choices that are present in the received representations or implied by the user’s manipulation of those representations It states that all transitions must be driven by the choices that are present in the representation. Does that mean that I can add an 'editURI' and a 'deleteURI' to each of the meeting i'm returning? if this information is there I can render the 'edit' button and if it's not there I just don't? What's the best practices on how to integrate the user's rights in the entity's representation? Or is this a super bad idea and another round trip is needed to fetch that information?

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• Does complex JOINs causes high coupling and maintenance problems ?

  - by ashkan.kh.nazary

  Our project has ~40 tables with complex relations.A colleague believes in using long join queries which enforces me to learn about tables outside of my module but I think I should not concern about tables not directly related to my module and use data access functions (written by those responsible for other modules) when I need data from them. Let me clarify: I am responsible for the ContactVendor module which enables the customers to contact the vendor and start a conversation about some specific product. Products module has it's own complex tables and relations with functions that encapsulate details (for example i18n, activation, product availability etc ...). Now I need to show the product title of some product related to some conversation between the vendor and customers. I may either write a long query that retrieves the product info along with conversation stuff in one shot (which enforces me to learn about Product tables) OR I may pass the relevant product_id to the get_product_info(int) function. First approach is obviously demanding and introduces many bad practices and things I normally consider fault in programming. The problem with the second approach seems to be the countless mini queries these access functions cause and performance loss is a concern when a loop tries to fetch product titles for 100 products using functions that each perform a separate query. So I'm stuck between "don't code to the implementation, code to interface" and performance. What is the right way of doing things ? UPDATE: I'm specially concerned about possible future modifications to those tables outside of my module. What if the Products module decided to change the way they are doing things? or for some reason modify the schema? It means some other modules would break or malfunction until the change is integrated to them. The usual ripple effect problem.

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• Good guidelines for developing an ecommerce application

  - by kaciula

  I'm making an ecommerce application on Android and, as it is my first serious project, I'm trying to figure out beforehand the best approach to do this. The application talks to a web service (magento api, meaning soap or xml rpc unfortunately) and gets all the content on the phone (product categories, product details, user credentials etc.). I think it should do lazy loading or something like that. So, I was thinking to keep the user credentials in a custom Object which will be kept in a SharedPreferences so that every Activity cand easily access it. I'll use a couple of ListViews to show the content and AsyncTask to fetch the data needed. Should I keep all the data in memory in objects or should I use some sort of cache or a local database? Also, I'm planning to use a HashMap with SoftReferences to hold the bitmaps I am downloading. But wouldn't this eat a lot of memory? How cand all the activities have access to all these objects (ecommerce basket etc.)? I'm thinking of passing them using Intents but this doesn't seem right to me. Can SharedPreferences be used for a lot of objects and are there any concurrency issues? Any pointers would be really appreciated. What are some good guidelines? What classes should I look into? Do you know of any resources on the Internet for me to check out?

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• Updating a local sqlite db that is used for local metadata & caching from an service?

  - by Pharaun

  I've searched through the site and haven't found a question/answer that quite answer my question, the closest one I found was: Syncing objects between two disparate systems best approach. Anyway to begun, because there is no RSS feeds available, I'm screen scrapping a webpage, hence it does a fetch then it goes through the webpage to scrap out all of the information that I'm interested in and dumps that information into a sqlite database so that I can query the information at my leisure without doing repeat fetching from the website. However I'm also storing various metadata on the data itself that is stored in the sqlite db, such as: have I looked at the data, is the data new/old, bookmark to a chunk of data (Think of it as a collection of unrelated data, and the bookmark is just a pointer to where I am in processing/reading of the said data). So right now my current problem is trying to figure out how to update the local sqlite database with new data and/or changed data from the website in a manner that is effective and straightforward. Here's my current idea: Download the page itself Create a temporary table for the parsed data to go into Do a comparison between the official and the temporary table and copy updates and/or new information to the official table This process seems kind of complicated because I would have to figure out how to determine if the data in the temporary table is new, updated, or unchanged. So I am wondering if there isn't a better approach or if anyone has any suggestion on how to architecture/structure such system?

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• retrieving object information with Doctrine

  - by ajsie

  i want to fetch information from the database using objects. i really like this approach cause this is more OOP: $user = Doctrine_Core::getTable('User')->find(1); echo $user->Email['address']; echo $user->Phonenumbers[0]->phonenumber; rather than: $q = Doctrine_Query::create() ->from('User u') ->leftJoin('u.Email e') ->leftJoin('u.Phonenumbers p') ->where('u.id = ?', 1); $user = $q->fetchOne(); echo $user->Email['address']; echo $user->Phonenumbers[0]['phonenumber']; the problem is that the first one uses 3 queries (3 different tables), while the second one uses only 1 (and is therefore recommended technique). but i feel that it destroys the object oriented design. cause ORM is meant to give us an OOP approach so that we could focus on objects and not the relational database. but now they want us to go back to use SQL like pattern. there isn't a way to get information form multiple tables not using DQL? the above examples are taken from the documentation: doctrine

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• MySQL LEFT JOIN, INNER JOIN etc, complicated query, PHP + MySQL for a forum

  - by Sven Eriksson

  So I've got a little forum I'm trying to get data for, there are 4 tables, forum, forum_posts, forum_threads and users. What i'm trying to do is to get the latest post for each forum and giving the user a sneak peek of that post, i want to get the number of posts and number of threads in each forum aswell. Also, i want to do this in one query. So here's what i came up with: SELECT lfx_forum_posts.*, lfx_forum.*, COUNT(lfx_forum_posts.pid) as posts_count, lfx_users.username, lfx_users.uid, lfx_forum_threads.tid, lfx_forum_threads.parent_forum as t_parent, lfx_forum_threads.text as t_text, COUNT(lfx_forum_threads.tid) as thread_count FROM lfx_forum LEFT JOIN (lfx_forum_threads INNER JOIN (lfx_forum_posts INNER JOIN lfx_users ON lfx_users.uid = lfx_forum_posts.author) ON lfx_forum_threads.tid = lfx_forum_posts.parent_thread AND lfx_forum_posts.pid = (SELECT MAX(lfx_forum_posts.pid) FROM lfx_forum_posts WHERE lfx_forum_posts.parent_forum = lfx_forum.fid GROUP BY lfx_forum_posts.parent_forum) ) ON lfx_forum.fid = lfx_forum_posts.parent_forum GROUP BY lfx_forum.fid ORDER BY lfx_forum.fid ASC This get the latest post in each forum and gives me a sneakpeek of it, the problem is that lfx_forum_posts.pid = (SELECT MAX(lfx_forum_posts.pid) FROM lfx_forum_posts WHERE lfx_forum_posts.parent_forum = lfx_forum.fid GROUP BY lfx_forum_posts.parent_forum) Makes my COUNT(lfx_forum_posts.pid) go to one (aswell as the COUNT(lfx_forum_threads.tid) which isn't how i would like it to work. My question is: is there some somewhat easy way to make it show the correct number and at the same time fetch the correct post info (the latest one that is)? If something is unclear please tell and i'll try to explain my issue further, it's my first time posting something here.

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• Variable amount of columns returned in mysqli prepared statement

  - by manyxcxi

  I have a situation where a dynamic query is being generated that could select anywhere from 1 to over 300 different columns across multiple tables. It currently works fine just doing a query, however the issue I'm running into in using a prepared statement is that I do not know how to handle the fact that I don't know how many columns I will be asking for each time and therefor don't know how to process the results. The reason I believe a bind statement will help is because once this query is run once, it will most likely (though not always) be run again with the exact same parameters. Currently I have something like this: $rows = array(); $this->statement = $this->db->prepare($query); $this->statement->bind_param('i',$id); $this->statement->execute(); $this->statement->bind_result($result); while($this->statement->fetch()) { $rows[] = $result; } I know this doesn't work as I want it to, my question is how do I get the data back out of the query. Is it possible to bring the columns back in an associative array by column name, like a standard mysqli query?

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• fullCalendar: Implementing a custom event fetcher using event as function

  - by Nick-ACNB

  If I specify a json feed, the events are re-fetched everytime and the fetching time shows the item appearing which causes a delay which is undesirable (at least after initial fetch was done). I am using the latest version from gitHub 1.4.6. The lazyFetching property seems to only work when you change views and you previously fetched for example a month and are drilling down to week/day which is unusable since I only use agendaDay. Here is what I am trying to achieve: $("#calendar").fullCalendar({ events: function(start, end, callback) { $.getJSON( "/GetEvents", { start: start.valueOf() }, function(data, textStatus) { $.each(data, function(i, event) { //Goal here is to only add items that aren't already rendered. if ($("#calendar") .fullCalendar('clientEvents', event.id)=="") $("#calendar").fullCalendar('renderEvent', event, true); }); } ); }); The goal is to use the sticky property in the renderEvent method so that on-screen they aren't re-rendered if they we're previously fetched. I omitted a part where I manually delete those that we're deleted and modify those that we're updated since I am in multi-user settings but you get the point. My issue is that they are fetched once and added. But once I change day and come back, they don't render even if I used sticky... has anyone gotten this error or did I code anything wrong? Also, is this a wrong way to go? I will consider any input. :) Thank you very much.

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• Delphi RTTI unable to find interface

  - by conciliator

  I'm trying to fetch an interface using D2010 RTTI. program rtti_sb_1; {$APPTYPE CONSOLE} {$M+} uses SysUtils, Rtti, mynamespace in 'mynamespace.pas'; var ctx: TRttiContext; RType: TRttiType; MyClass: TMyIntfClass; begin ctx := TRttiContext.Create; MyClass := TMyIntfClass.Create; // This prints a list of all known types, including some interfaces. // Unfortunately, IMyPrettyLittleInterface doesn't seem to be one of them. for RType in ctx.GetTypes do WriteLn(RType.Name); // Finding the class implementing the interface is easy. RType := ctx.FindType('mynamespace.TMyIntfClass'); // Finding the interface itself is not. RType := ctx.FindType('mynamespace.IMyPrettyLittleInterface'); MyClass.Free; ReadLn; end. Both IMyPrettyLittleInterface and TMyIntfClass = class(TInterfacedObject, IMyPrettyLittleInterface) are declared in mynamespace.pas. Do anyone know why this doesn't work? Is there a way to solve my problem? Thanks in advance!

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• Delphi TRttiType.GetMethods return zero TRttiMethod instances

  - by conciliator

  I've recently been able to fetch a TRttiType for an interface using TRttiContext.FindType using Robert Loves "GetType"-workaround ("registering" the interface by an explicit call to ctx.GetType, e.g. RType := ctx.GetType(TypeInfo(IMyPrettyLittleInterface));). One logical next step would be to iterate the methods of said interface. Consider program rtti_sb_1; {$APPTYPE CONSOLE} uses SysUtils, Rtti, mynamespace in 'mynamespace.pas'; var ctx: TRttiContext; RType: TRttiType; Method: TRttiMethod; begin ctx := TRttiContext.Create; RType := ctx.GetType(TypeInfo(IMyPrettyLittleInterface)); if RType <> nil then begin for Method in RType.GetMethods do WriteLn(Method.Name); end; ReadLn; end. This time, my mynamespace.pas looks like this: IMyPrettyLittleInterface = interface ['{6F89487E-5BB7-42FC-A760-38DA2329E0C5}'] procedure SomeProcedure; end; Unfortunately, RType.GetMethods returns a zero-length TArray-instance. Are there anyone able to reproduce my troubles? (Note that in my example I've explicitly fetched the TRttiType using TRttiContext.GetType, not the workaround; the introduction is included to warn readers that there might be some unresolved issues regarding rtti and interfaces.) Thanks!

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• Seperate html pages for each screen in Jquery mobile

  - by vrs

  I am newbie to Jquery Mobile, so far what ever examples i searched contains only one html page for whole application, with multipe div tags where each page/screen is defined as div tag with data-role as page with some header and footers optionally. Based on user actions, we are hiding some div's(pages) and showing only expected page. Also, this multi-page template seems to be standard design, as written by some blogs. Are there any other designing ways? what I would like to have is multipe html pages, for ex one for login, one for home, one for contact etc. Other wise it is difficult to understand/code/debug issues, especially people from Java background like me.So, what I want is some kind of MVC design with JQueryMobile, like each view/screen as sepearate html associated with one js (Controller). Can we have multiple html pages in JqueryMobile app? If possible how to pass data/ maintain session between them? Any samples are most welcome. Thanks In Advance. Note: Also I don't want server side includes, may app contains 10 to 15 screens, each page will make a webservice call and fetch some data and map it to UI.

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• NHibernate collections: many-to-many relationships

  - by Brad Heller

  I've got two models, a Product model and a ShoppingCart model. The ShoppingCart model has a collection of products as a property called Products (List). Here is the mapping for my ShoppingCart model. <class name="MyProject.ShoppingCart, MyProject" table="ShoppingCarts"> <id name="Id" column="Id"> <generator class="native" /> </id> <many-to-one name="Company" class="MyProject.Company, MyProject" column="CompanyId" /> <property name="ExternalId" column="GUID" generated="insert" /> <property name="Name" column="Name" /> <property name="Total" column="Total" /> <property name="CreationDate" column="CreationDate" generated="insert" /> <property name="UpdatedDate" column="UpdatedDate" generated="always" /> <bag name="Products" table="ShoppingCartContents" lazy="false"> <key column="ShoppingCartId" /> <many-to-many column="ProductId" class="MyProjectMyProject.Product, MyProject" fetch="join" /> </bag> </class> When I try to save to the DB, the ShoppingCart is saved, but the mapping rows in ShoppingCartContents aren't save, making me thing that there's an issue with the mapping. Where am I going wrong here?

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• Distributing a bundle of files across an extranet

  - by John Zwinck

  I want to be able to distribute bundles of files, about 500 MB per bundle, to all machines on a corporate "extranet" (which is basically a few LANs connected using various private mechanisms, including leased lines and VPN). The total number of hosts is roughly 100, and the goal is to get a copy of the bundle from one host onto all the other hosts reliably, quickly, and efficiently. One important issue is that some hosts are grouped together on single fast LANs in which case the network I/O should be done once from one group to the next and then within each group between all the peers. This is as opposed to a strict central server system where multiple hosts might each fetch the same bundle over a slow link, rather than once via the slow link and then between each other quickly. A new bundle will be produced every few days, and occasionally old bundles will be deleted (but that problem can be solved separately). The machines in question happen to run recent Linuxes, but bonus points will go to solutions which are at least somewhat cross-platform (in which case the bundle might differ per platform but maybe the same mechanism can be used). That's pretty much it. I'm not opposed to writing some code to handle this, but it would be preferable if it were one of bash, Python, Ruby, Lua, C, or C++.

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• Parallel version of loop not faster than serial version

  - by Il-Bhima

  I'm writing a program in C++ to perform a simulation of particular system. For each timestep, the biggest part of the execution is taking up by a single loop. Fortunately this is embarassingly parallel, so I decided to use Boost Threads to parallelize it (I'm running on a 2 core machine). I would expect at speedup close to 2 times the serial version, since there is no locking. However I am finding that there is no speedup at all. I implemented the parallel version of the loop as follows: Wake up the two threads (they are blocked on a barrier). Each thread then performs the following: Atomically fetch and increment a global counter. Retrieve the particle with that index. Perform the computation on that particle, storing the result in a separate array Wait on a job finished barrier The main thread waits on the job finished barrier. I used this approach since it should provide good load balancing (since each computation may take differing amounts of time). I am really curious as to what could possibly cause this slowdown. I always read that atomic variables are fast, but now I'm starting to wonder whether they have their performance costs. If anybody has some ideas what to look for or any hints I would really appreciate it. I've been bashing my head on it for a week, and profiling has not revealed much.

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• Lost with hibernate - OneToMany resulting in the one being pulled back many times..

  - by Andy

  I have this DB design: CREATE TABLE report ( ID MEDIUMINT PRIMARY KEY NOT NULL AUTO_INCREMENT, user MEDIUMINT NOT NULL, created TIMESTAMP NOT NULL, state INT NOT NULL, FOREIGN KEY (user) REFERENCES user(ID) ON UPDATE CASCADE ON DELETE CASCADE ); CREATE TABLE reportProperties ( ID MEDIUMINT NOT NULL, k VARCHAR(128) NOT NULL, v TEXT NOT NULL, PRIMARY KEY( ID, k ), FOREIGN KEY (ID) REFERENCES report(ID) ON UPDATE CASCADE ON DELETE CASCADE ); and this Hibernate Markup: @Table(name="report") @Entity(name="ReportEntity") public class ReportEntity extends Report{ @Id @GeneratedValue(strategy = GenerationType.AUTO) @Column(name="ID") private Integer ID; @Column(name="user") private Integer user; @Column(name="created") private Timestamp created; @Column(name="state") private Integer state = ReportState.RUNNING.getLevel(); @OneToMany(mappedBy="pk.ID", fetch=FetchType.EAGER) @JoinColumns( @JoinColumn(name="ID", referencedColumnName="ID") ) @MapKey(name="pk.key") private Map<String, ReportPropertyEntity> reportProperties = new HashMap<String, ReportPropertyEntity>(); } and @Table(name="reportProperties") @Entity(name="ReportPropertyEntity") public class ReportPropertyEntity extends ReportProperty{ @Embeddable public static class ReportPropertyEntityPk implements Serializable{ /** * long#serialVersionUID */ private static final long serialVersionUID = 2545373078182672152L; @Column(name="ID") protected int ID; @Column(name="k") protected String key; } @EmbeddedId protected ReportPropertyEntityPk pk = new ReportPropertyEntityPk(); @Column(name="v") protected String value; } And i have inserted on Report and 4 Properties for that report. Now when i execute this: this.findByCriteria( Order.asc("created"), Restrictions.eq("user", user.getObject(UserField.ID)) ) ); I get back the report 4 times, instead of just the once with a Map with the 4 properties in. I'm not great at Hibernate to be honest, prefer straight SQL but I must learn, but i can't see what it is that is wrong.....? Any suggestions?

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• Nhibernate: Stop it from joining to a table that is not needed

  - by Aaron

  I have two tables (tbArea, tbPost) that relate to the following classes. class Area { int ID string Name ... } class Post { int ID string Title Area Area ... } These two classes map up with Fluent Nhibernate. Below is the post mapping. public class PostMapping : ClassMap<Post> { public PostMapping() { Cache.NonStrictReadWrite(); this.Table("tbPost"); Id(x => x.ID) .Column("PostID") .GeneratedBy .Identity(); References(x => x.Area) .ForeignKey("AreaID") .Column("AreaID"); ... } } Any time I perform a query on the Post table "where AreaID = 1(any AreaId)", nhibernate will join to the area table. (What Nhibernate generates for a query) SELECT post fields , area fields (automatically added) FROM tbPost p LEFT JOIN tbArea a on p.areaid = a.areaid where p.areaid = 1 I have tried setting Area to LazyLoad, to Fetch.Select, ReadOnly, and any other setting on the reference and still it will always join to Area. I am trying to optimize the backend database queries, and since I don't need the area object loaded just filtered I would like to eliminate the unnecessary join to Area each time I Query post. What configurations do I need to change or mappings to get area to still be related to post in my objects, but not query it when I filter on AreaID?

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• I'm trying to build a query to search against a fulltext index in mysql

  - by Rockinelle

  The table's schema is pretty simple. I have a child table that stores a customer's information like address and phone number. The columns are user_id, fieldname, fieldvalue and fieldname. So each row will hold one item like phone number, address or email. This is to allow an unlimited number of each type of information for each customer. The people on the phones need to look up these customers quickly as they call into our call center. I have experimented with using LIKE% and I'm working with a FULLTEXT index now. My queries work, but I want to make them more useful because if someone searches for a telephone area code like 805 that will bring up many people, and then they add the name Bill to narrow it down, '805 Bill'. It will show EVERY customer that has 805 OR Bill. I want it to do AND searches across multiple rows within each customer. Currently I'm using the query below to grab the user_ids and later I do another query to fetch all the details for each user to build their complete record. SELECT DISTINCT `user_id` FROM `user_details` WHERE MATCH (`fieldvalue`) AGAINST ('805 Bill') Again, I want to do the above query against groups of rows that belong to a single user, but those users have to match the search keywords. What should I do?

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• FQL query using stream table doesn't accept app access token

  - by tougher

  I've searched stackoverflow all day long to find an answer without luck, so here we go. I'm trying to fetch data from the stream table like this: FQL: SELECT post_id, message, created_time FROM stream WHERE source_id = 131559313586863 URL: http:// graph.facebook.com/fql?q=SELECT+post_id%2C+message%2C+created_time+FROM+stream+WHERE+source_id+%3D+131559313586863&access_token=10669xxxxx74470|PF-7GSdBx0Nxxxxxkdi1KwSQG-w But I get a 400 Bad Request as response with the error message: "An access token is required to request this resource.". I'm fetching an application access token with this url: https:// graph.facebook.com/oauth/access_token?client_id=FACEBOOK_APP_ID&client_secret=FACEBOOK_APP_SECRET&grant_type=client_credentials Facebook state in this blog post that "You will need to pass a valid app or user access token to access this functionality.". Functionality refers to /feed and /posts (the stream table). Futhermore this wiki tells the same story about using the stream table, "From June 3 2011 a token is required to query this table. You can use any application or user token to make the query.". Does anyone see my hopefully obvious flaw? Please note: The profile in the FQL query is public. I need this to run userless though a cronjob. No user interaction is possible. The request works if I replace the app access token with my own user token from https:// developers.facebook.com/tools/explorer Sorry for breaking the URL's. I need more reputation to post more than 2 links :-/

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• iPhone NSCFString leaks in fetchRequest

  - by camilo

  In the following code: - (NSMutableArray *) fetchNotesForGroup: (NSString *)groupName { // Variables declaration NSMutableArray *result; NSFetchRequest *fetchRequest; NSEntityDescription *entity; NSSortDescriptor *sortDescriptor; NSPredicate *searchPredicate; NSError *error = nil; // Creates the fetchRequest and executes it fetchRequest = [[[NSFetchRequest alloc] init] autorelease]; entity = [NSEntityDescription entityForName:@"Note" inManagedObjectContext:managedObjectContext]; [fetchRequest setEntity:entity]; sortDescriptor = [[[NSSortDescriptor alloc] initWithKey:@"noteName" ascending:YES] autorelease]; [fetchRequest setSortDescriptors:[NSArray arrayWithObject:sortDescriptor]]; [fetchRequest setReturnsDistinctResults:YES]; searchPredicate = [NSPredicate predicateWithFormat:@"categoryName like %@", groupName]; [fetchRequest setPredicate:searchPredicate]; [fetchRequest setPropertiesToFetch:[NSArray arrayWithObject:@"noteName"]]; result = [[managedObjectContext executeFetchRequest:fetchRequest error:&error] mutableCopy]; // Variables release return result; } ... I Fetch notes for a given categoryName. When I'm running Instruments, it says that a NSCFString is leaking. I know leaks are mean for iPhone developers... but I don't have any idea on how to plug this one. Any clues? All help is welcome. Thanks a lot!

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