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  • rookie MySql question about paging; Is one query enough?

    - by Camran
    I have managed to get paging to work, almost. I want to display to the user, total nr of records found, and the currently displayed records. Ex: 4000 found, displaying 0-100. I am testing this with the nr 2 (because I don't have that many records, have like 20). So I am using LIMIT $start, $nr_results; Do I have to make two queries in order to display the results the way I want, one query fetching all records and then make a mysql_num_rows to get all records, then the one with the LIMIT ? I have this: mysql_num_rows($qry_result); $total_pages = ceil($num_total / $res_per_page); //$res_per_page==2 and $num_total = 2 if ($p - 10 < 1) { $pagemin=1; } else { $pagemin = $p - 10; } if ($p + 10 $total_pages) { $pagemax = $total_pages; } else { $pagemax = $p + 10; } Here is the query: SELECT mt.*, fordon.*, boende.*, elektronik.*, business.*, hem_inredning.*, hobby.* FROM classified mt LEFT JOIN fordon ON fordon.classified_id = mt.classified_id LEFT JOIN boende ON boende.classified_id = mt.classified_id LEFT JOIN elektronik ON elektronik.classified_id = mt.classified_id LEFT JOIN business ON business.classified_id = mt.classified_id LEFT JOIN hem_inredning ON hem_inredning.classified_id = mt.classified_id LEFT JOIN hobby ON hobby.classified_id = mt.classified_id ORDER BY modify_date DESC LIMIT 0, 2 Thanks, if you need more input let me know. Basically Q is, do I have to make two queries?

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  • Twitter api - no more than 150 requests per hour....

    - by RenegadeAndy
    Hi. I am writing a twitter app using jtwitter - and its running inside a server inside my work. Anyway - whenever i run it from work it returns the error below and I am only making a couple requests per hour: HTTP/1.1 400 Bad Request {"request":"/1/statuses/user_timeline.json?count=6&id=cicsdemo&","error":"Rate limit exceeded. Clients may not make more than 150 requests per hour."} ] 2010-06-03 18:44:49 zero.timer.TimerTask::run Thread-3 SEVERE [ CWPZA3100E: Exception during processing for timer task, "twitterTimer". Exception: java.lang.ClassCastException: winterwell.jtwitter.Twitter$Status incompatible with java.lang.String ] I run the same code from home - its fine. So obviously at some point twitter thinks our work is all coming from one direct IP - which is why its hitting a limit which it shouldnt. Do I have any choice or workaround - can i make the limit be counted from my direct machine IP - or to my account instead of IP? Can i use a proxy? Has any body else had this problem and solved it?! Before anyone asks the APP must live inside my work - it cannot run anywhere else! Cheers, Andy

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  • GROUP BY ID range?

    - by d0ugal
    Given a data set like this; +-----+---------------------+--------+ | id | date | result | +-----+---------------------+--------+ | 121 | 2009-07-11 13:23:24 | -1 | | 122 | 2009-07-11 13:23:24 | -1 | | 123 | 2009-07-11 13:23:24 | -1 | | 124 | 2009-07-11 13:23:24 | -1 | | 125 | 2009-07-11 13:23:24 | -1 | | 126 | 2009-07-11 13:23:24 | -1 | | 127 | 2009-07-11 13:23:24 | -1 | | 128 | 2009-07-11 13:23:24 | -1 | | 129 | 2009-07-11 13:23:24 | -1 | | 130 | 2009-07-11 13:23:24 | -1 | | 131 | 2009-07-11 13:23:24 | -1 | | 132 | 2009-07-11 13:23:24 | -1 | | 133 | 2009-07-11 13:23:24 | -1 | | 134 | 2009-07-11 13:23:24 | -1 | | 135 | 2009-07-11 13:23:24 | -1 | | 136 | 2009-07-11 13:23:24 | -1 | | 137 | 2009-07-11 13:23:24 | -1 | | 138 | 2009-07-11 13:23:24 | 1 | | 139 | 2009-07-11 13:23:24 | 0 | | 140 | 2009-07-11 13:23:24 | -1 | +-----+---------------------+--------+ How would I go about grouping the results by day 5 records at a time. The above results is part of the live data, there is over 100,000 results rows in the table and its growing. Basically I want to measure the change over time, so want to take a SUM of the result every X records. In the real data I'll be doing it ever 100 or 1000 but for the data above perhaps every 5. If i could sort it by date I would do something like this; SELECT DATE_FORMAT(date, '%h%i') ym, COUNT(result) 'Total Games', SUM(result) as 'Score' FROM nn_log GROUP BY ym; I can't figure out a way of doing something similar with numbers. The order is sorted by the date but I hope to split the data up every x results. It's safe to assume there are no blank rows. Doing it above with the data you could do multiple selects like; SELECT SUM(result) FROM table LIMIT 0,5; SELECT SUM(result) FROM table LIMIT 5,5; SELECT SUM(result) FROM table LIMIT 10,5; Thats obviously not a very good way to scale up to a bigger problem. I could just write a loop but I'd like to reduce the number of queries.

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  • What should be the potential reason to get runtime error for this program?

    - by MiNdFrEaK
    #include<iostream> #include<stack> #include<vector> #include<string> #include<fstream> #include<cstdlib> /*farnaws,C++,673,08/12/2012*/ using namespace std; string verifier(string input_line) { stack <char> braces; for(int i=0; i<input_line.size(); i++) { if(input_line[i]=='(' || input_line[i]=='[') { braces.push(input_line[i]); } else if(input_line[i]==')' || input_line[i]==']') { braces.pop(); } } if(braces.size()==0) { return "YES"; } else { return "NO"; } } int main() { ifstream file_input("input.in"); string read_file; vector<string> file_contents; if(file_input.is_open()) { while(file_input>>read_file) { file_contents.push_back(read_file); } } else { cout<<"File cant be open!"<<endl; } int limit=atoi(file_contents[0].c_str()); //cout<< limit; ofstream file_output("output.out"); if(file_output.is_open()) { for(int i=1; i<=limit; i++ ) { file_output<<verifier(file_contents[i])<<endl; } } else { cout<<"File cant be open!"<<endl; } return 0; }

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  • Rails log shows unexpected data as to the time spent on a DB stuff

    - by Arhimed
    I'm running on WinXP + Ruby 1.8.6 + Rails 2.3.5 (frozen to the project) in development environment. Looking at development.log I observe inconsistent data as to the time spent on a database stuff. Example #1 (good): Processing PagesController#index (for 127.0.0.1 at 2010-05-11 12:15:54) [GET] Parameters: {"action"=>"index", "controller"=>"pages"} City Columns (563.0ms) SHOW FIELDS FROM `cities` City Load (15.0ms) SELECT * FROM `cities` WHERE (`cities`.`short_name` = 'NY') LIMIT 1 Redirected to http://xyz:3000/sightings Completed in 953ms (DB: 578) | 302 Found [http://xyz/] Example #2 (unexpected): Processing PagesController#index (for 127.0.0.1 at 2010-05-11 12:15:36) [GET] Parameters: {"action"=>"index", "controller"=>"pages"} City Columns (0.0ms) SHOW FIELDS FROM `cities` City Load (0.0ms) SELECT * FROM `cities` WHERE (`cities`.`short_name` = 'NY') LIMIT 1 Redirected to http://xyz:3000/sightings Completed in 47ms (DB: 32) | 302 Found [http://xyz/] Example #2 shows 32ms were spent on DB while there were just 2 sql querries and both of zero time spent. Example #3 (unexpected): Processing PagesController#index (for 127.0.0.1 at 2010-05-11 11:21:24) [GET] Parameters: {"action"=>"index", "controller"=>"pages"} City Columns (63.0ms) SHOW FIELDS FROM `cities` City Load (62.0ms) SELECT * FROM `cities` WHERE (`cities`.`short_name` = 'NY') LIMIT 1 Redirected to http://xyz:3000/sightings Completed in 1187ms (DB: 297) | 302 Found [http://xyz/] Example #3 shows 297ms while there were querries of 63ms and 62ms (125ms in total). Can't understand it. Could someone explain? Thanks in advance.

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  • How to query multiple tables with multiple selects MySQL

    - by brybam
    I'm trying to write a php function that gets all the basic food data(this part works fine in my code) Then grabs all the ingredients related to the ids of the selected items from the query before. Anyone have have any idea why my second array keeps coming back as false? I should be getting 1 array with the list of foods (this works) Then, the second one should be an array with all the ingredients for all the foods that were previously selected...then in my code im planning to work with the array and sort them with the proper foods based on the ids. function getFood($start, $limit) { $one = mysql_query("SELECT a.id, a.name, a.type, AVG(b.r) AS fra, COUNT(b.id) as tvotes FROM `foods` a LEFT JOIN `foods_ratings` b ON a.id = b.id GROUP BY a.id ORDER BY fra DESC, tvotes DESC LIMIT $start, $limit;"); $row = mysql_fetch_array($one); $qry = ""; foreach ($row as &$value) { $fid = $value['id']; $qry = $qry . "SELECT ing, amount FROM foods_ing WHERE fid='$fid';"; } $two = mysql_query($qry); return array ($one, $two); }

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  • Patterns / Solutions to complicated Feature Management

    - by yclian
    Hi all, My company develops CDN / Web-Hosting solution. We have a middleware that's served as a business logic layer and exposes web service for the front-end. I would like to seek for a clean solution to feature management - there're uncertainties and ugly workarounds/solutions in the software that the dev would say "when it happens or is broken, we will fix it". For example, here're the following features that a web publisher can have: Sites limit Bandwidth limit SSL feature + SSL configuration per site If we downgrade a web publisher, when he's having 10 sites, down to 5 sites, we can choose not to suspend the rest of the 5 sites, or we shall prompt for suspension before the downgrade. For the case of bandwidth limit, the downgrade is easy, when the bandwidth check happens, if the publisher has it exceeded, then we will suspend his account. For the case of SSL feature. Every SSL configuration is tied to a site, what shall happen to these configuration object when the SSL feature is downgraded from enabled to disabled? So as you can see, there're many different situations and there are different ways of handling it. I can make a system that examines the impacts and prompts the user to make changes before the downgrade/upgrade. Or a system that ignores the impacts and just upgrade/downgrade. Bad. Or a system designed in a way that the client code need to be aware of the complex feature matrix (or I can expose a helper to the client code to check if a feature is not DEFUNCT) There can be many ways that I am still thinking but puzzled. I am wondering, how would you tackle this issue and is there any recommended patterns or books or software that you think I can refer to? Appreciate your help.

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  • how to allow unamed user in svn authz file?

    - by dtrosset
    I have a subversion server running with apache. It authenticates users using LDAP in apache configuration and uses SVN authorizations to limit user access to certain repositories. This works perfectly. Apache DAV svn SVNParentPath /srv/svn SVNListParentPath Off SVNPathAuthz Off AuthType Basic AuthName "Subversion Repository" AuthBasicProvider ldap AuthLDAPBindDN # private stuff AuthLDAPBindPassword # private stuff AuthLDAPURL # private stuff Require valid-user AuthzSVNAccessFile /etc/apache2/dav_svn.authz Subversion [groups] soft = me, and, all, other, developpers Adding anonymous access from one machine Now, I have a service I want to setup (rietveld, for code reviews) that needs to have an anonymous access to the repository. As this is a web service, accesses are always done from the same server. Thus I added apache configuration to allow all accesses from this machine. This did not work until I add an additional line in the authorization file to allow read access to user -. Apache <Limit GET PROPFIND OPTIONS REPORT> Order allow,deny Allow from # private IP address Satisfy Any </Limit> Subversion [Software:/] @soft = rw - = r # <-- This is the added line For instance, before I add this, all users were authenticated, and thus had a name. Now, some accesses are done without a user name! I found this - user name in the apache log files. But does this line equals to * = r that I absolutely do not want to enable, or does it only allows the anonymous unnamed user (that is allowed access only from the rietveld server)?

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  • SQL Server 2008 R2

    - by kevchadders
    Hi all, I heard on the grapevine that Microsoft will be releasing SQL Server 2008 R2 within a year. Though I initially thought this was a patch for the just released 2008 version, I realised that it’s actually a completely different version that you would have to pay for. (Am I correct, if you had SQL Server 2008, would you have to pay again if you wanted to upgrade to 2008 R2?) If you’re already running SQL Server 2008, would you say it’s still worth the upgrade? Or does it depend on the size of your company and current setup. For what I’ve initially read, I do get the impression that this version would be more useful for the very high end hardware setup where you want to have very good scalability. With regard to programming, is there any extra enhancements/support in there which you’re aware of that will significantly help .NET Products/Web Development? Initially found a couple of links on it, but I was wondering if anyone had anymore info to share on subject as I couldn’t find nothing on SO about it? Thanks. New SQL Server R2 Microsoft Link on it. Microsoft SQL 2008 R2 EDIT: More information based on the Express Edition One very interesting thing about SQL Server 2008 R2 concerns the Express edition. Previous express versions of SQL Server Express had a database size limit of 4GB. With SQL Server Express 2008 R2, this has now been increased to 10GB !! This now makes the FREE express edition a much more viable option for small & medium sized applications that are relatively light on database requirements. Bear in mind, that this limit is per database, so if you coded your application cleverly enough to use a separate database for historical/archived data, you could squeeze even more out of it! For more information, see here: http://blogs.msdn.com/sqlexpress/archive/2010/04/21/database-size-limit-increased-to-10gb-in-sql-server-2008-r2-express.aspx

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  • Rationale of C# iterators design (comparing to C++)

    - by macias
    I found similar topic: http://stackoverflow.com/questions/56347/iterators-in-c-stl-vs-java-is-there-a-conceptual-difference Which basically deals with Java iterator (which is similar to C#) being unable to going backward. So here I would like to focus on limits -- in C++ iterator does not know its limit, you have by yourself compare the given iterator with the limit. In C# iterator knows more -- you can tell without comparing to any external reference, if the iterator is valid or not. I prefer C++ way, because once having iterator you can set any iterator as a limit. In other words if you would like to get only few elements instead of entire collection, you don't have to alter the iterator (in C++). For me it is more "pure" (clear). But of course MS knew this and C++ while designing C#. So what are the advantages of C# way? Which approach is more powerful (which leads to more elegant functions based on iterators). What do I miss? If you have thoughts on C# vs. C++ iterators design other than their limits (boundaries), please also answer. Note: (just in case) please, keep the discussion strictly technical. No C++/C# flamewar.

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  • Deleting unneeded rows from a table with 2 criteria

    - by stormbreaker
    Hello. I have a many-to-many relations table and I need to DELETE the unneeded rows. The lastviews table's structure is: | user (int) | document (int) | time (datetime) | This table logs the last users which viewed the document. (user, document) is unique. I show only the last 10 views of a document and until now I deleted the unneeded like this: DELETE FROM `lastviews` WHERE `document` = ? AND `user` NOT IN (SELECT * FROM (SELECT `user` FROM `lastviews` WHERE `document` = ? ORDER BY `time` DESC LIMIT 10) AS TAB) However, now I need to also show the last 5 documents a user has viewed. This means I can no longer delete rows using the previous query because it might delete information I need (say a user didn't view documents in 5 minutes and the rows are deleted) To sum up, I need to delete all the records that don't fit these 2 criterias: SELECT ... FROM `lastviews` WHERE `document` = ? ORDER BY `time` DESC LIMIT 10 and SELECT * FROM `lastviews` WHERE `user` = ? ORDER BY `time` DESC LIMIT 0, 5 I need the logic. Thanks in advance.

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  • mysql query not running correctly from inside the application

    - by Mala
    I am completely stumped. Here is my php (CodeIgniter) code: function mod() { $uid = $this->session->userdata('uid'); $pid = $this->input->post('pid'); if ($this->_verify($uid,$pid)) { $name = $this->input->post('name'); $price = $this->input->post('price'); $curr = $this->input->post('curr'); $url = $this->input->post('url'); $query = $this->db->query("UPDATE items SET name=".$this->db->escape($name).", price=".$this->db->escape($price).", currency=".$this->db->escape($curr),", url=".$this->db->escape($url)." WHERE pid=".$this->db->escape($pid)." LIMIT 1"); } header('location: '.$this->session->userdata('current')); } The purpose of this code is to modify the properties (name, price, currency, url) of a row in the 'items' table (priary key is pid). However, for some reason, allowing this function to run once modifies the name, price, currency and url of ALL entries in the table, regardless of their pid and of the LIMIT 1 thing I tacked on the end of the query. It's as if the last line of the query is being completely ignored. As if this wasn't strance enough, I replaced "$query = $this->db->query(" with an "echo" to see the SQL query being run, and it outputs a query much like I would expect: UPDATE items SET name='newname', price='newprice', currency='newcurrency', url='newurl' WHERE pid='10' LIMIT 1 Copy-pasting this into a MySQL window acts exactly as I want: it modifies the row with the selected pid. What is going on here???

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  • Use where clause with Like in codeigniter

    - by user2524013
    I am working on a project. I am implementing the Search functionality in my System. I will have to show the search record from two tables base on the current use login. I have tried the following code: function searchActivity($limit,$offset,$keyword1,$keyword2,$recruiter_id) { $q=$this->db->select('*')->from('tbl_activity')->limit($limit,$offset); $this->db->join('tbl_job', 'tbl_job.job_id = tbl_activity.job_id_fk', 'left outer'); $this->db->order_by("activity_id", "ASC"); $this->db->like('job_title',$keyword1,'both'); $this->db->or_like('job_title',$keyword2,'both'); $this->db->or_like('activity_subject',$keyword1,'both'); $this->db->or_like('activity_subject',$keyword2,'both'); $this->db->or_like('activity_details',$keyword1,'both'); $this->db->or_like('activity_details',$keyword2,'both'); $this->db->where('tbl_activity.recruiter_id_fk',$recruiter_id); $ret['rows']=$q->get()->result(); return $ret; } I want to show search results based on the current user id, which is currently store in $recruiter. Thanks in advance.

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  • Page_Load or Page_Init

    - by balexandre
    Let's take a really simple example on using jQuery to ajaxify our page... $.load("getOrders.aspx", {limit: 25}, function(data) { // info as JSON is available in the data variable }); and in the ASP.NET (HTML part) page (only one line) <%@ Page Language="C#" AutoEventWireup="true" CodeFile="getOrders.aspx.cs" Inherits="getOrders" %> and in the ASP.NET (Code Behind) page public partial class getOrders : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { string lmt = Request["limit"]; List<Orders> ords = dll.GetOrders(limit); WriteOutput( Newtonsoft.Json.JsonConvert.SerializeObject(ords) ); } private void WriteOutput(string s) { Response.Clear(); Response.Write(s); Response.Flush(); Response.End(); } } my question is Should it be protected void Page_Load(object sender, EventArgs e) or protected void Page_Init(object sender, EventArgs e) So we can save some milliseconds as we don't actually need to process the events for the page, or will Page_Init lack of some sorting of a method by the time it is called? P.S. Currently works fine in both methods, but I just want to understand the ins and outs of choosing one method over the other

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  • Query syntax error selecting from 3 tables

    - by Toni Michel Caubet
    Given info about an object: id, user_id, group_id Given info about an user: id_user, id_loc I need to get i one query: The name of the user (in table users) The name of the location of the user (in table locs) The name of the group of the object (in table groups) I am trying like this: SELECT usuarios.first_name as username, usuarios.id as userid, usuarios.avatar as useravatar, usuarios.id_loc, locs.name as locname, groups.name as groupname FROM usuarios,groups,locs WHRE usuarios.id_loc = locs.id AND usuarios.id = 1 AND group.id = LIMIT 1 having an error saying You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'AND locs.id = 3 LIMIT 1' at line 3 What am i doing wrong? can i do this in one query? -EDIT- This is the query generator code (php+mysql): $query_loc_group_user = 'SELECT usuarios.first_name as username, usuarios.id as userid, usuarios.avatar as useravatar, usuarios.id_loc, locs.name as locname, groups.name as groupname FROM usuarios,groups,locs WHRE usuarios.id_loc = locs.id AND usuarios.id = '.$this->id_user.' AND group.id = '.$this->id_group.' LIMIT 1'; In case it helps, i am trying to do in one query this function get_info(){ $info; $result = cache_query('SELECT first_name,last_name,avatar FROM usuarios WHERE id = '.$this->id_user); foreach($result as $extra){ $info['username'] = $extra['first_name'].' '.$extra['last_name']; $info['avatar'] = $extra['avatar']; } $result1 = cache_query('SELECT name FROM locs WHERE id = '.$this->id_user); foreach($result1 as $extra){ $info['locname'] = $extra['name']; } $result2 = cache_query('SELECT name FROM locs WHERE id = '.$this->id_user); foreach($result2 as $extra){ $info['groupname'] = $extra['name']; } return $info; }

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  • PHP: How to know if a user is currently downloading a file?

    - by metrobalderas
    I'm developing a quick rapidshare-like site where the user can download files. First, I created a quick test setting headers and using readfile() but then I found in the comments section there's a way to limit the speed of the download, which is great, here's the code: $local_file = 'file.zip'; $download_file = 'name.zip'; // set the download rate limit (=> 20,5 kb/s) $download_rate = 20.5; if(file_exists($local_file) && is_file($local_file)) { header('Cache-control: private'); header('Content-Type: application/octet-stream'); header('Content-Length: '.filesize($local_file)); header('Content-Disposition: filename='.$download_file); flush(); $file = fopen($local_file, "r"); while(!feof($file)) { // send the current file part to the browser print fread($file, round($download_rate * 1024)); // flush the content to the browser flush(); // sleep one second sleep(1); } fclose($file);} else { die('Error: The file '.$local_file.' does not exist!'); } But now my question is, how to limit the number of downloads at the same time? How can I check there's still a connection with some user's IP? Thanks.

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  • How do I create a self referential association (self join) in a single class using ActiveRecord in Rails?

    - by Daniel Chang
    I am trying to create a self join table that represents a list of customers who can refer each other (perhaps to a product or a program). I am trying to limit my model to just one class, "Customer". The schema is: create_table "customers", force: true do |t| t.string "name" t.integer "referring_customer_id" t.datetime "created_at" t.datetime "updated_at" end add_index "customers", ["referring_customer_id"], name: "index_customers_on_referring_customer_id" My model is: class Customer < ActiveRecord::Base has_many :referrals, class_name: "Customer", foreign_key: "referring_customer_id", conditions: {:referring_customer_id => :id} belongs_to :referring_customer, class_name: "Customer", foreign_key: "referring_customer_id" end I have no problem accessing a customer's referring_customer: @customer.referring_customer.name ... returns the name of the customer that referred @customer. However, I keep getting an empty array when accessing referrals: @customer.referrals ... returns []. I ran binding.pry to see what SQL was being run, given a customer who has a "referer" and should have several referrals. This is the SQL being executed. Customer Load (0.3ms) SELECT "customers".* FROM "customers" WHERE "customers"."id" = ? ORDER BY "customers"."id" ASC LIMIT 1 [["id", 2]] Customer Exists (0.2ms) SELECT 1 AS one FROM "customers" WHERE "customers"."referring_customer_id" = ? AND "customers"."referring_customer_id" = 'id' LIMIT 1 [["referring_customer_id", 3]] I'm a bit lost and am unsure where my problem lies. I don't think my query is correct -- @customer.referrals should return an array of all the referrals, which are the customers who have @customer.id as their referring_customer_id.

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  • Jquery Ajax refresh not working in IE.

    - by Probocop
    Hi, I have a <ul> which refreshes every ten seconds to check if there have been any new tweets (its pulling from a twitter feed). This works fine in Firefox and Chrome etc, but it does not work in any version if Internet Explorer. My code is as follows: setInterval(function() { $("#banter .scroll-pane").load(location.href+" #banter .scroll-pane>*",""); }, 10000); My PHP function creating the list is as follows: function showTweets($section, $limit, $class) { $result = mysql_query("SELECT * FROM hash WHERE section = '".$section."' ORDER BY date DESC LIMIT ".$limit); echo '<ul class="scroll-pane '.$class.'">'; while($row = mysql_fetch_array($result)) { echo '<li>'; echo '<p>'.html_entity_decode($row['tweet']).'</p>'; echo '<a href="'.$row['user_url'].'">'.$row['user'].'</a>'; echo '</li>'; } echo '</ul>'; } Any idea what's going wrong? Thanks

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  • BIOS interrupts, privilege levels and paging

    - by Jack
    Hi, I was learning about Intel 8086-80486 CPUs and their interactions with HW. But I still don´t understand it quite well. Please, help me fill blank spots. First, I know that CPU communicates with HW using BIOS interrupts. But, what really happens in PC, when I call some INT instruction? I know that according the interrupt table some instructions begin to execute, but how by executing some instructions can BIOS recognize what I want to do? Becouse as far as I know, CPU has no extra communication channel with BIOS, it can only adress memory and receive data. So how can I instruct BIOS to do something, when I can only address RAM? Next thing I don't understand is about privilege levels. I know about ring model, and access rights, but how does the CPU know which privilege level has executed an instruction? I think that these privileges apply only when intruction is trying to address memory, but how does an application get its privilege level? I mean I know its level 3, but how is it set? And last thing, I know that paging is address scheme that is used to support aplication-transparent virtual memory, or swapping, but I could not find any information about how paging is tied with protected mode. Like if paging is like next mode independent of protected mode, or its somehow implemented within protected mode. And if it is implemented in protected mode, isn´t it too slow, to first address application space, then offset, and then paging folder, page and offset once again?

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  • BIOS interrupts, priviledge levels and paging

    - by Jack
    Hi, I was learning about Intel 8086-80486 CPUs and their interactions with HW. But I still don´t understand it quite well. Please, help me fill blank spots. First, I know that CPU communicates with HW using BIOS interrupts. But, what really happens in PC, when I call some INT instruction? I know that according the interrupt table some instructions begin to execute, but how by executing some instructions can BIOS recognize what I want to do? Becouse as far as I know, CPU has no extra communication channel with BIOS, it can only adress memory and receive data. So how can I instruct BIOS to do something, when I can only adress RAM? Next thing I dont understand is about priviledge levels. I know about ring model, and acess rights, but how CPU knows which priviledge level has executed instruction? I think that these priviledges apply only when intruction is trying to adress memory, but how applications gets its priviledge level? I mean I know its level 3, but how its set? And last thing, I know that paging is adress scheme that is used to support aplication-transparent virtual memory, or swaping, but I could not find any informations about how is paging tied with protected mode. Like if paging is like next mode independent of protectet mode, or its somehow implemented within protected mode. And if it is implemented in protected mode, isn´t it too slow, to first adress application space, than offset, and than paging folder, page and offset once again? Thank you for every response.

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  • PHP-FPM and APC for shared hosting?

    - by Tiffany Walker
    We are looking into finding a way to get APC to only create one cache per account / site. This can be done with Fastcgi (last update 2006…) but with Fastcgid APC will have to create multiple caches for multiple processes run by the same account. To get around this problem, we have been looking into PHP-FPM PHP process manager allows multiple PHP processes to share a single APC cache. But from what I have read (I hope I'm wrong) , even if you create a pool per process, all sites accross all pools will share the same APC cache. This brings us back to the same problem as with shared Memcached: it's not secure ! On php-fpm's site I read that you can chroot php-fpm pools and define a specific UID and GID per pool… if this is the case then shouldn't APC have to use this user and not have access to other pools cache ? An article here (in 2011) suggests that you would need to run one process per pool creating multiple launchers on different ports and different config files with one pool per config file : http://groups.drupal.org/node/198168 Is this still neceessary ? If so what would be the impact of running say 800 processes of php-fpm ? Would it be mainly memory ? If so how can I work out what the memory impact would be ? I guess that it would be better to run 800 times php-fpm then to have accounts creating multiple APC caches for a single site ? If on average an account creates a 50MB cache and creates 3 caches per account that makes 150Mb per account which makes 120GB… However if each account uses on average only 50Mb that would make 40GB We will have at least 128GB of ram on our next server so 40GB is acceptable if running 800 x PHP-FPM does not create an overhead of more than 20GB ! What do you think is PHP-FPM the best way to go to provide secure APC cache on shared hosting with a server that has a decent amount of memory ? Or should I be looking at another system ? Thanks !

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  • The boot selection failed because a required device is inaccessible 0xc000000e

    - by bbodenmiller
    A family member of mine recently went on vacation and turned off their computer, something they normally do not do, upon returning home it would not turn on and now returns the error message below. Generally friends and family come to me for help with computers and I have no problem, however this time I am a bit stumped. Any suggestions would be greatly appreciated. As you can see the error message is: Status: 0xc000000e Info: The best selection failed because a required device is inaccessible. Before going to this error message it briefly flashes the Windows loading screen. I have been able to confirm through the Windows RE Command Line and the dir command that the C: drive is accessible and likely is just suffering a bootup issue. I have tried: Launching the repair process discussed in the error message three times however each time it requires a restart and then returns to the same error message. Changing the boot order to be hard drive first Getting into safe mode; F8 just results in the same error message before I can get to the menu to select safe mode I have checked to make sure the BCD (bcdedit, Boot Configuration Data) is still intact as per https://www.symantec.com/business/support/index?page=content&id=TECH160475 I plan to try (but would like additional comments on): sfc /scannow; requires a restart and thus will likely result in the error message again A memory scan Bootrec as per http://support.microsoft.com/kb/927392#method1 Swapping IDE cables/ports Resetting the BIOS I noticed others with similar issues around the web are dual-booting however this machine is not setup in a dual-boot environment. Additionally at one point this error message supposedly showed up before I started working on the computer: The instruction at 0xfbe2584d referenced memory at 0x00000008. The memory could not be read. As previously stated any additional suggestions or words of advice would be greatly apprecaited.

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  • How to set shmall, shmmax, shmni, etc ... in general and for postgresql

    - by jpic
    I've used the documentation from PostgreSQL to set it for example this config: >>> cat /proc/meminfo MemTotal: 16345480 kB MemFree: 1770128 kB Buffers: 382184 kB Cached: 10432632 kB SwapCached: 0 kB Active: 9228324 kB Inactive: 4621264 kB Active(anon): 7019996 kB Inactive(anon): 548528 kB Active(file): 2208328 kB Inactive(file): 4072736 kB Unevictable: 0 kB Mlocked: 0 kB SwapTotal: 0 kB SwapFree: 0 kB Dirty: 3432 kB Writeback: 0 kB AnonPages: 3034588 kB Mapped: 4243720 kB Shmem: 4533752 kB Slab: 481728 kB SReclaimable: 440712 kB SUnreclaim: 41016 kB KernelStack: 1776 kB PageTables: 39208 kB NFS_Unstable: 0 kB Bounce: 0 kB WritebackTmp: 0 kB CommitLimit: 8172740 kB Committed_AS: 14935216 kB VmallocTotal: 34359738367 kB VmallocUsed: 399340 kB VmallocChunk: 34359334908 kB HardwareCorrupted: 0 kB AnonHugePages: 456704 kB HugePages_Total: 0 HugePages_Free: 0 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 2048 kB DirectMap4k: 12288 kB DirectMap2M: 16680960 kB >>> ipcs -l ------ Shared Memory Limits -------- max number of segments = 4096 max seg size (kbytes) = 4316816 max total shared memory (kbytes) = 4316816 min seg size (bytes) = 1 ------ Semaphore Limits -------- max number of arrays = 128 max semaphores per array = 250 max semaphores system wide = 32000 max ops per semop call = 32 semaphore max value = 32767 ------ Messages Limits -------- max queues system wide = 31918 max size of message (bytes) = 8192 default max size of queue (bytes) = 16384 sysctl.conf extract: kernel.shmall = 1079204 kernel.shmmax = 4420419584 postgresql.conf non defaults: max_connections = 60 # (change requires restart) shared_buffers = 4GB # min 128kB work_mem = 4MB # min 64kB wal_sync_method = open_sync # the default is the first option checkpoint_segments = 16 # in logfile segments, min 1, 16MB each checkpoint_completion_target = 0.9 # checkpoint target duration, 0.0 - 1.0 effective_cache_size = 6GB Is this appropriate ? If not (or not necessarily), in which case would it be appropriate ? We did note nice performance improvements with this config, how would you improve it ? How should kernel memory management parameters be set ? Can anybody explain how to really set them from the ground up ?

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  • Laptop choice for development: MacBook Pro 17 vs Dell Studio XPS 16 vs HP Envy 15

    - by Shalan
    Hey! First things first - let me state that I am not intending to play games on this - I have narrowed down to these 3 purely based on specs and its individual brand reliability in the market. I intend to primarily use: Visual Studio 2008 Pro a lot (develop and deploy on Windows platforms) SQL Server 2005 Oracle 10g Adobe Photoshop CS4 Microsoft Expression Studio Google Sketchup I currently use a desktop PC (Core2Duo 2.66Ghz with 3GB DDRII memory) running Vista Business 32-bit - and I have to admit that, especially for Visual Studio, its quite sluggish to a point where it affects productivity. Furthermore, I intend to only use the notebook on a table - with a cooled surface, like granite :) - so I would appreciate people's input with regard to heat issues. Im aware that the Dell's primary exhaust gets blocked by the lid when open, but some reviews don't seem to place extraordinary emphasis on heat issues resulting from this. My options for the Dell/Alienware: Core i7 720QM 4GB DDRIII memory ATI mobility 3670 (512) 128GB Solid State Drive 16-inch Full HD RGB-LED LCD display (1080p) 3-year next-business-day support My configuration for the Apple MBP: Core2Duo 2.8Ghz (Im assuming the T9600) 4GB DDRIII memory 128GB Solid State Drive standard 1 year support The one advantage I think of with the MBP is that I can have the addition of OSX (though Im unsure what I would use it for, but purely to play around with a much-boasted-about OS) What are your thoughts on this, especially regarding build-quality, heat, performance and battery-life? Much thanks! ~shalan

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  • Why does my computer crash randomly?

    - by Donavon Decker
    The other day I went out to my van to get my Tower and when I opened the trunk it fell out. I brought it into the house and opened it, and everything looked ok. When I started it up, about 1-3 minutes afterwards it would crash. It did this over and over until I reseated the cooler. Everything seemed normal again, until after about 10 minutes of gameplay (any game), it would crash. I reseated my GPU + reinstalled the drivers, however I still get the same error. A while back, I'd check my 'Windows Rating' periodically, and all of them were in the '6.0-6.9' range except for my hard disk usage (always been like that [not relative]). Today I went in and looked, and my Processor and Memory was rated 5.4. I reseated my cpu and my memory, refreshed the windows rating, and then my processor and memory went from 5.4, to 5.1. A few minutes ago I reseated them once again, and now it's back to 5.4. Note: Not sure if this is relevant to the issue, but I updated my bios earlier today I honestly have no idea what the issue is, but I'm getting aggravated at the problem. Here are some images which contain images of my specifications: i1271.photobucket.com/albums/jj623/donxdeck/1_zps09f0607c.jpg i1271.photobucket.com/albums/jj623/donxdeck/4_zps381cd00a.jpg i1271.photobucket.com/albums/jj623/donxdeck/3_zps54bba720.jpg i1271.photobucket.com/albums/jj623/donxdeck/2_zps945d3d72.jpg Thanks for the help

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