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  • If I take a large datatype. Will it affect performance in sql server

    - by Shantanu Gupta
    If i takes larger datatype where i know i should have taken datatype that was sufficient for possible values that i will insert into a table will affect any performance in sql server in terms of speed or any other way. eg. IsActive (0,1,2,3) not more than 3 in any case. I know i must take tinyint but due to some reasons consider it as compulsion, i am taking every numeric field as bigint and every character field as nVarchar(Max) Please give statistics if possible, to let me try to overcoming that compulsion. I need some solid analysis that can really make someone rethink before taking any datatype.

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  • Improving the performance of an nHibernate Data Access Layer.

    - by Amitabh
    I am working on improving the performance of DataAccess Layer of an existing Asp.Net Web Application. The scenerios are. Its a web based application in Asp.Net. DataAccess layer is built using NHibernate 1.2 and exposed as WCF Service. The Entity class is marked with DataContract. Lazy loading is not used and because of the eager-fetching of the relations there is huge no of database objects are loaded in the memory. No of hits to the database is also high. For example I profiled the application using NHProfiler and there were about 50+ sql calls to load one of the Entity object using the primary key. I also can not change code much as its an existing live application with no NUnit test cases at all. Please can I get some suggestions here?

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  • Can using non primitive Integer/ Long datatypes too frequently in the application, hurt the performance??

    - by Marcos
    I am using Long/Integer data types very frequently in my application, to build Generic datatypes. I fear that using these wrapper objects instead of primitive data types may be harmful for performance since each time it needs to create objects which is an expensive operation. but also it seems that I have no other choice(when I have to use primtives with generics) rather than just using them. However, still it would be great if you can suggest if there is anything I could do to make it better. or any way if I could just avoid it ?? Also What may be the downsides of this ? Suggestions welcomed!

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  • Performance optimization for mssql: decrease stored procedures execution time or unload the server?

    - by tim
    Hello everybody! We have a web service which provides search over hotels. There is a problem with performance: a single request to the service takes around 5000 ms. Almost all of the time is spent in database by executing storing procedures. During the request our server (mssql2008) consumes ~90% of the processor time. When 2 requests are made in parallel the average time grows and is around 7000 ms. When number of request is increasing, the average time of response is increasing as well. We have 20-30 requests per minute. Which kind of optimization is the best in this case having in mind that the goal is to provide stable response time for the service: 1) Try to decrease the stored procedures execution time 2) Try to find the way how to unload the server It is interesting to hear from people who deal with booking sites. Thanks!

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  • How can I login to a website with Python?

    - by Shady
    How can I do it? I was trying to enter some specified link (with urllib), but to do it, I need to log in. I have this source from the site: <form id="login-form" action="auth/login" method="post"> <div> <!--label for="rememberme">Remember me</label><input type="checkbox" class="remember" checked="checked" name="remember me" /--> <label for="email" id="email-label" class="no-js">Email</label> <input id="email-email" type="text" name="handle" value="" autocomplete="off" /> <label for="combination" id="combo-label" class="no-js">Combination</label> <input id="password-clear" type="text" value="Combination" autocomplete="off" /> <input id="password-password" type="password" name="password" value="" autocomplete="off" /> <input id="sumbitLogin" class="signin" type="submit" value="Sign In" /> Is this possible?

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  • What's the most performance effective way to have a webbrowser inside a class library ?

    - by Xaqron
    I'm developing a class library. Need some data from internet and this cannot be done with HttpWebRequest in my case so I wanna use WebBrowser component. WebBrowser is used for opening a single page and fetch some data from it, so WebBrowser life-time is very short. Running thread is MTA and no message pump or STA thread is available by default (class library is used by an ASP.NET application). How to create a WebBrowser object, run it with a STA thread, fetch data from a web page and finally dispose it with the least performance impact on the application ? I just need the idea/concept and will find details myself. Thanks guys

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  • JavaScript: String Concatenation slow performance? Array.join('')?

    - by NickNick
    I've read that if I have a for loop, I should not use string concation because it's slow. Such as: for (i=0;i<10000000;i++) { str += 'a'; } And instead, I should use Array.join(), since it's much faster: var tmp = []; for (i=0;i<10000000;i++) { tmp.push('a'); } var str = tmp.join(''); However, I have also read that string concatention is ONLY a problem for Internet Explorer and that browsers such as Safari/Chrome, which use Webkit, actually perform FASTER is using string concatention than Array.join(). I've attempting to find a performance comparison between all major browser of string concatenation vs Array.join() and haven't been able to find one. As such, what is faster and more efficient JavaScript code? Using string concatenation or Array.join()?

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  • SQL SEVER – Finding Memory Pressure – External and Internal

    - by pinaldave
    Following query will provide details of external and internal memory pressure. It will return the data how much portion in the existing memory is assigned to what kind of memory type. SELECT TYPE, SUM(single_pages_kb) InternalPressure, SUM(multi_pages_kb) ExtermalPressure FROM sys.dm_os_memory_clerks GROUP BY TYPE ORDER BY SUM(single_pages_kb) DESC, SUM(multi_pages_kb) DESC GO What is your method to find memory pressure? Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Optimization, SQL Performance, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • Are SMART goals useful for programmers?

    - by Craig Schwarze
    Several organisations I know use SMART goals for their programmers. SMART is an acronym for Specific, Measurable, Achievable, Relevant and Time-Bound. They are fairly common in large corporations. My own prior experience with SMART goals has not been all that positive. Have other programmers found them an effective way to measure performance? What are some examples of good SMART goals for programmers (if they exist).

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  • SQL SERVER – Difference Between DATETIME and DATETIME2

    - by pinaldave
    Yesterday I have written a very quick blog post on SQL SERVER – Difference Between GETDATE and SYSDATETIME and I got tremendous response for the same. I suggest you read that blog post before continuing this blog post today. I had asked people to honestly take part and share their view about above two system function. There are few emails as well few comments on the blog post asking question how did I come to know the difference between the same. The answer is real world issues. I was called in for performance tuning consultancy where I was asked very strange question by one developer. Here is the situation he was facing. System had a single table with two different column of datetime. One column was datelastmodified and second column was datefirstmodified. One of the column was DATETIME and another was DATETIME2. Developer was populating them with SYSDATETIME respectively. He was always thinking that the value inserted in the table will be the same. This table was only accessed by INSERT statement and there was no updates done over it in application.One fine day he ran distinct on both of this column and was in for surprise. He always thought that both of the table will have same data, but in fact they had very different data. He presented this scenario to me. I said this can not be possible but when looked at the resultset, I had to agree with him. Here is the simple script generated to demonstrate the problem he was facing. This is just a sample of original table. DECLARE @Intveral INT SET @Intveral = 10000 CREATE TABLE #TimeTable (FirstDate DATETIME, LastDate DATETIME2) WHILE (@Intveral > 0) BEGIN INSERT #TimeTable (FirstDate, LastDate) VALUES (SYSDATETIME(), SYSDATETIME()) SET @Intveral = @Intveral - 1 END GO SELECT COUNT(DISTINCT FirstDate) D_GETDATE, COUNT(DISTINCT LastDate) D_SYSGETDATE FROM #TimeTable GO SELECT DISTINCT a.FirstDate, b.LastDate FROM #TimeTable a INNER JOIN #TimeTable b ON a.FirstDate = b.LastDate GO SELECT * FROM #TimeTable GO DROP TABLE #TimeTable GO Let us see the resultset. You can clearly see from result that SYSDATETIME() does not populate the same value in the both of the field. In fact the value is either rounded down or rounded up in the field which is DATETIME. Event though we are populating the same value, the values are totally different in both the column resulting the SELF JOIN fail and display different DISTINCT values. The best policy is if you are using DATETIME use GETDATE() and if you are suing DATETIME2 use SYSDATETIME() to populate them with current date and time to accurately address the precision. As DATETIME2 is introduced in SQL Server 2008, above script will only work with SQL SErver 2008 and later versions. I hope I have answered few questions asked yesterday. Reference: Pinal Dave (http://www.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL DateTime, SQL Optimization, SQL Performance, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • SQL SERVER – When are Statistics Updated – What triggers Statistics to Update

    - by pinaldave
    If you are an SQL Server Consultant/Trainer involved with Performance Tuning and Query Optimization, I am sure you have faced the following questions many times. When is statistics updated? What is the interval of Statistics update? What is the algorithm behind update statistics? These are the puzzling questions and more. I searched the Internet as well many official MS documents in order to find answers. All of them have provided almost similar algorithm. However, at many places, I have seen a bit of variation in algorithm as well. I have finally compiled the list of various algorithms and decided to share what was the most common “factor” in all of them. I would like to ask for your suggestions as whether following the details, when Statistics is updated, are accurate or not. I will update this blog post with accurate information after receiving your ideas. The answer I have found here is when statistics are expired and not when they are automatically updated. I need your help here to answer when they are updated. Permanent table If the table has no rows, statistics is updated when there is a single change in table. If the number of rows in a table is less than 500, statistics is updated for every 500 changes in table. If the number of rows in table is more than 500, statistics is updated for every 500+20% of rows changes in table. Temporary table If the table has no rows, statistics is updated when there is a single change in table. If the number of rows in table is less than 6, statistics is updated for every 6 changes in table. If the number of rows in table is less than 500, statistics is updated for every 500 changes in table. If the number of rows in table is more than 500, statistics is updated for every 500+20% of rows changes in table. Table variable There is no statistics for Table Variables. If you want to read further about statistics, I suggest that you read the white paper Statistics Used by the Query Optimizer in Microsoft SQL Server 2008. Let me know your opinions about statistics, as well as if there is any update in the above algorithm. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, Readers Question, SQL, SQL Authority, SQL Optimization, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: SQL Statistics

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  • SQL SERVER – Checklist for Analyzing Slow-Running Queries

    - by pinaldave
    I am recently working on upgrading my class Microsoft SQL Server 2005/2008 Query Optimization and & Performance Tuning with additional details and more interesting examples. While working on slide deck I realized that I need to have one solid slide which talks about checklist for analyzing slow running queries. A quick search on my saved [...]

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  • Add Free Google Apps to Your Website or Blog

    - by Matthew Guay
    Would you like to have an email address from your own domain, but prefer Gmail’s interface and integration with Google Docs?  Here’s how you can add the free Google Apps Standard to your site and get the best of both worlds. Note: To signup for Google Apps and get it setup on your domain, you will need to be able to add info to your WordPress blog or change Domain settings manually. Getting Started Head to the Google Apps signup page (link below), and click the Get Started button on the right.  Note that we are signing up for the free Google Apps which allows a max of 50 users; if you need more than 50 email addresses for your domain, you can choose Premiere Edition instead for $50/year. Select that you are the Administrator of the domain, and enter the domain or subdomain you want to use with Google Apps.  Here we’re adding Google Apps to the techinch.com site, but we could instead add Apps to mail.techinch.com if needed…click Get Started. Enter your name, phone number, an existing email address, and other Administrator information.  The Apps signup page also includes some survey questions about your organization, but you only have to fill in the required fields. On the next page, enter a username and password for the administrator account.  Note that the user name will also be the administrative email address as [email protected]. Now you’re ready to authenticate your Google Apps account with your domain.  The steps are slightly different depending on whether your site is on WordPress.com or on your own hosting service or server, so we’ll show how to do it both ways.   Authenticate and Integrate Google Apps with WordPress.com To add Google Apps to a domain you have linked to your WordPress.com blog, select Change yourdomain.com CNAME record and click Continue. Copy the code under #2, which should be something like googleabcdefg123456.  Do not click the button at the bottom; wait until we’ve completed the next step.   Now, in a separate browser window or tab, open your WordPress Dashboard.  Click the arrow beside Upgrades, and select Domains from the menu. Click the Edit DNS link beside the domain name you’re adding to Google Apps. Scroll down to the Google Apps section, and paste your code from Google Apps into the verification code field.  Click Generate DNS records when you’re done. This will add the needed DNS settings to your records in the box above the Google Apps section.  Click Save DNS records. Now, go back to the Google Apps signup page, and click I’ve completed the steps above. Authenticate Google Apps on Your Own Server If your website is hosted on your own server or hosting account, you’ll need to take a few more steps to add Google Apps to your domain.  You can add a CNAME record to your domain host using the same information that you would use with a WordPress account, or you can upload an HTML file to your site’s main directory.  In this test we’re going to upload an HTML file to our site for verification. Copy the code under #1, which should be something like googleabcdefg123456.  Do not click the button at the bottom; wait until we’ve completed the next step first. Create a new HTML file and paste the code in it.  You can do this easily in Notepad: create a new document, paste the code, and then save as googlehostedservice.html.  Make sure to select the type as All Files or otherwise the file will have a .txt extension. Upload this file to your web server via FTP or a web dashboard for your site.  Make sure it is in the top level of your site’s directory structure, and try visiting it at yoursite.com/googlehostedservice.html. Now, go back to the Google Apps signup page, and click I’ve completed the steps above. Setup Your Email on Google Apps When this is done, your Google Apps account should be activated and ready to finish setting up.  Google Apps will offer to launch a guide to step you through the rest of the process; you can click Launch guide if you want, or click Skip this guide to continue on your own and go directly to the Apps dashboard.   If you choose to open the guide, you’ll be able to easily learn the ropes of Google Apps administration.  Once you’ve completed the tutorial, you’ll be taken to the Google Apps dashboard. Most of the Google Apps will be available for immediate use, but Email may take a bit more setup.  Click Activate email to get your Gmail-powered email running on your domain.    Add Google MX Records to Your Server You will need to add Google MX records to your domain registrar in order to have your mail routed to Google.  If your domain is hosted on WordPress.com, you’ve already made these changes so simply click I have completed these steps.  Otherwise, you’ll need to manually add these records before clicking that button.   Adding MX Entries is fairly easy, but the steps may depend on your hosting company or registrar.  With some hosts, you may have to contact support to have them add the MX records for you.  Our site’s host uses the popular cPanel for website administration, so here’s how we added the MX Entries through cPanel. Add MX Entries through cPanel Login to your site’s cPanel, and click the MX Entry link under Mail. Delete any existing MX Records for your domain or subdomain first to avoid any complications or interactions with Google Apps.  If you think you may want to revert to your old email service in the future, save a copy of the records so you can switch back if you need. Now, enter the MX Records that Google listed.  Here’s our account after we added all of the entries to our account. Finally, return to your Google Apps Dashboard and click the I have completed these steps button at the bottom of the page. Activating Service You’re now officially finished activating and setting up your Google Apps account.  Google will first have to check the MX records for your domain; this only took around an hour in our test, but Google warns it can take up to 48 hours in some cases. You may then see that Google is updating its servers with your account information.  Once again, this took much less time than Google’s estimate. When everything’s finished, you can click the link to access the inbox of your new Administrator email account in Google Apps. Welcome to Gmail … at your own domain!  All of the Google Apps work just the same in this version as they do in the public @gmail.com version, so you should feel right at home. You can return to the Google Apps dashboard from the Administrative email account by clicking the Manage this domain at the top right. In the Dashboard, you can easily add new users and email accounts, as well as change settings in your Google Apps account and add your site’s branding to your Apps. Your Google Apps will work just like their standard @gmail.com counterparts.  Here’s an example of an inbox customized with the techinch logo and a Gmail theme. Links to Remember Here are the common links to your Google Apps online.  Substitute your domain or subdomain for yourdomain.com. Dashboard https://www.google.com/a/cpanel/yourdomain.com Email https://mail.google.com/a/yourdomain.com Calendar https://www.google.com/calendar/hosted/yourdomain.com Docs https://docs.google.com/a/yourdomain.com Sites https://sites.google.com/a/yourdomain.com Conclusion Google Apps offers you great webapps and webmail for your domain, and let’s you take advantage of Google’s services while still maintaining the professional look of your own domain.  Setting up your account can be slightly complicated, but once it’s finished, it will run seamlessly and you’ll never have to worry about email or collaboration with your team again. Signup for the free Google Apps Standard Similar Articles Productive Geek Tips Mysticgeek Blog: Create Your Own Simple iGoogle GadgetAccess Your Favorite Google Services in Chrome the Easy WayRevo Uninstaller Pro [REVIEW]Mysticgeek Blog: A Look at Internet Explorer 8 Beta 1 on Windows XPFind Similar Websites in Google Chrome TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips Xobni Plus for Outlook All My Movies 5.9 CloudBerry Online Backup 1.5 for Windows Home Server Snagit 10 Video preview of new Windows Live Essentials 21 Cursor Packs for XP, Vista & 7 Map the Stars with Stellarium Use ILovePDF To Split and Merge PDF Files TimeToMeet is a Simple Online Meeting Planning Tool Easily Create More Bookmark Toolbars in Firefox

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  • Directory structure for a website (js/css/img folders)

    - by nightcoder
    For years I've been using the following directory structure for my websites: <root> ->js ->jquery.js ->tooltip.js ->someplugin.js ->css ->styles.css ->someplugin.css ->images -> all website images... it seemed perfectly fine to me until I began to use different 3rd-party components. For example, today I've downloaded a datetime picker javascript component that looks for its images in the same directory where its css file is located (css file contains urls like "url('calendar.png')"). So now I have 3 options: 1) put datepicker.css into my css directory and put its images along. I don't really like this option because I will have both css and image files inside the css directory and it is weird. Also I might meet files from different components with the same name, such as 2 different components, which link to background.png from their css files. I will have to fix those name collisions (by renaming one of the files and editing the corresponding file that contains the link). 2) put datepicker.css into my css directory, put its images into the images directory and edit datepicker.css to look for the images in the images directory. This option is ok but I have to spend some time to edit 3rd-party components to fit them to my site structure. Again, name collisions may occur here (as described in the previous option) and I will have to fix them. 3) put datepicker.js, datepicker.css and its images into a separate directory, let's say /3rdParty/datepicker/ and place the files as it was intended by the author (i.e., for example, /3rdParty/datepicker/css/datepicker.css, /3rdParty/datepicker/css/something.png, etc.). Now I begin to think that this option is the most correct. Experienced web developers, what do you recommend?

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  • Easy Listening = CRM On Demand Podcasts

    - by Anne
    OK, here's my NEW favorite resource for CRM On Demand info -- podcasts! Specifically, the CRM On Demand Podcast site -- signed, sealed, and delivered with humor and know-how. Yes, I admit, I know the cast of characters. But let's face it, sometimes dealing with software is just soooo dry! Not so when discussed by the two main commentators, Louis Peters and Robert Davidson, whom someone once referred to as CRM On Demand's "Click and Clack." (Thought that was too good not to pass along!) Anyhow, another huge plus about the site is the option to listen OR to read. Out walking my dog or doing the dishes? Just turn up the podcast. Listening to music or watching TV? I'll read Louis's entertaining write-ups to glean great info about CRM On Demand in a very short period of time. So that you get a better understanding of why I like this site so much, here's a sampling of what's discussed: Five Things about Books of Business As Louis Peters put it in his entry, when you see "Five Things" in the title, "you'll know you're going to get some concrete advice that you can put to work right away." Well, Louis and Robert do just that, pointing you in the right direction when using Books of Business to segment data. Moving to Indexed Fields - A Rough Guide (only an article, not a podcast) I've read all about performance and even helped develop material around it. But nowhere have I heard indexed custom fields referred to as "super heroes." Louis and Robert use imaginative language to describe the process for moving your data to indexed fields for optimal performance. Data Access QA from the Forums I think that everyone would admit that data access and visibility is the most difficult topic to understand in CRM On Demand. Following up on their previous podcast on the same topic, Louis and Robert answer a few key questions from the many postings on the Oracle CRM On Demand forums. And I bet that the scenarios match many companies' business requirements...maybe even yours! We Need to Talk About Adoption Another expert, Tim Koehler, joins Louis to talk about how to drive user adoption: aligning product usage with business results, communicating why and how to use the product, getting feedback on usability, and so on. Hope I've made my point -- turn to these podcasts to hear knowledgeable folks discuss CRM On Demand tips and tricks in entertaining ways. One podcast is even called "SaaS Talk"!

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  • Certificate Revocation checking affecting system performance [migrated]

    - by Colm Clarke
    I have a .NET 3.5 desktop application that had been showing periodic slow downs in functionality whenever the test machine it was on was out of the office. I managed to replicate the error on a machine in the office without an internet connection, but it was only when i used ANTS performance profiler that i got a clearer picture of what was going on. In ANTS I saw a "Waiting for synchronization" taking up to 16 seconds that corresponded to the delay I could see in the application when NHibernate tried to load the System.Data.SqlServerCE.dll assembly. If I tried the action again immediately it would work with no delay but if I left it for 5 minutes then it would be slow to load again the next time I tried it. From my research so far it appears to be because the SqlServerCE dll is signed and so the system is trying to connect to get the certificate revocation lists and timing out. Disabling the "Automatically detect settings" setting in the Internet Options LAN settings makes the problem go away, as does disabling the "Check for publishers certificate revocation". But the admins where this application will be deployed are not going to be happy with the idea of disabling certificate checking on a per machine or per user basis so I really need to get the application level disabling of the CRL check working. There is the well documented bug in .net 2.0 which describes this behaviour, and offers a possible fix with a config file element. <?xml version="1.0" encoding="utf-8"?> <configuration> <runtime> <generatePublisherEvidence enabled="false"/> </runtime> </configuration> This is NOT working for me however even though I am using .net 3.5. The SQLServerCE dll is being loaded dynamically by NHibernate and I wonder if the fact that it's dynamic could somehow be why the setting isn't working, but I don't know how I could check that. Can anyone offer suggestions as to why the config setting might not work? Or is there another way I could disable the check at the application level, perhaps a CAS policy setting that I can use to set an exception for the application when it's installed? Or is there something I can change in the application to up the trust level or something like that? I have also tried using to no advantage ServicePointManager.CheckCertificateRevocationList = false; http://rusanu.com/2009/07/24/fix-slow-application-startup-due-to-code-sign-validation/ I have also tried those registry settings out and unfortunately they didn't help. The dlls that appear to be the cause of the hold up are native SQL Server CE dlls, and looking at the stack traces in ProcMon mscorwks.dll doesn't appear to be involved even though the checks on crypto and cert registry keys are being done under the .NET application. It's definitely still something to do with publisher certificate checking because unticking "Check for publisher revocation certificate" still works but something odd is going on.

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  • Switching website DNS with minimal downtime

    - by Gavin
    I need to change my domain's DNS, but here in Thailand the ISPs don't follow any standards for renewing their cache of records, so it can take the full two days. I have a new website with about 1,000 members currently who are sending messages and uploading photos. I don't want both sites on the old and new server running at the same time because then I'd have to manually merge the database and transfer uploaded photos. It would be a huge pain. Both servers also a unique URL from my host, e.g. website12345.hostingcompany.com (old host) and website67890.hostingcompany.com (new host). I don't have much experience with this, but I think what I can do is on www.mysite.com, use .htaccess to do a masked redirect to the new server's URL (website67890.hostingcompany.com). Is it possible to do this and keep all URLs being masked? For example, www.mysite.com/profile/username will actually be loading website12345.hostingcompany.com/profile/username. From Google searches it sounds like this is possible, but I don't understand why this is possible due to security issues, since what's keeping people from masking their site to URLs like facebook.com? I could really use some advice here! Thanks!

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  • The blocking nature of aggregates

    - by Rob Farley
    I wrote a post recently about how query tuning isn’t just about how quickly the query runs – that if you have something (such as SSIS) that is consuming your data (and probably introducing a bottleneck), then it might be more important to have a query which focuses on getting the first bit of data out. You can read that post here.  In particular, we looked at two operators that could be used to ensure that a query returns only Distinct rows. and The Sort operator pulls in all the data, sorts it (discarding duplicates), and then pushes out the remaining rows. The Hash Match operator performs a Hashing function on each row as it comes in, and then looks to see if it’s created a Hash it’s seen before. If not, it pushes the row out. The Sort method is quicker, but has to wait until it’s gathered all the data before it can do the sort, and therefore blocks the data flow. But that was my last post. This one’s a bit different. This post is going to look at how Aggregate functions work, which ties nicely into this month’s T-SQL Tuesday. I’ve frequently explained about the fact that DISTINCT and GROUP BY are essentially the same function, although DISTINCT is the poorer cousin because you have less control over it, and you can’t apply aggregate functions. Just like the operators used for Distinct, there are different flavours of Aggregate operators – coming in blocking and non-blocking varieties. The example I like to use to explain this is a pile of playing cards. If I’m handed a pile of cards and asked to count how many cards there are in each suit, it’s going to help if the cards are already ordered. Suppose I’m playing a game of Bridge, I can easily glance at my hand and count how many there are in each suit, because I keep the pile of cards in order. Moving from left to right, I could tell you I have four Hearts in my hand, even before I’ve got to the end. By telling you that I have four Hearts as soon as I know, I demonstrate the principle of a non-blocking operation. This is known as a Stream Aggregate operation. It requires input which is sorted by whichever columns the grouping is on, and it will release a row as soon as the group changes – when I encounter a Spade, I know I don’t have any more Hearts in my hand. Alternatively, if the pile of cards are not sorted, I won’t know how many Hearts I have until I’ve looked through all the cards. In fact, to count them, I basically need to put them into little piles, and when I’ve finished making all those piles, I can count how many there are in each. Because I don’t know any of the final numbers until I’ve seen all the cards, this is blocking. This performs the aggregate function using a Hash Match. Observant readers will remember this from my Distinct example. You might remember that my earlier Hash Match operation – used for Distinct Flow – wasn’t blocking. But this one is. They’re essentially doing a similar operation, applying a Hash function to some data and seeing if the set of values have been seen before, but before, it needs more information than the mere existence of a new set of values, it needs to consider how many of them there are. A lot is dependent here on whether the data coming out of the source is sorted or not, and this is largely determined by the indexes that are being used. If you look in the Properties of an Index Scan, you’ll be able to see whether the order of the data is required by the plan. A property called Ordered will demonstrate this. In this particular example, the second plan is significantly faster, but is dependent on having ordered data. In fact, if I force a Stream Aggregate on unordered data (which I’m doing by telling it to use a different index), a Sort operation is needed, which makes my plan a lot slower. This is all very straight-forward stuff, and information that most people are fully aware of. I’m sure you’ve all read my good friend Paul White (@sql_kiwi)’s post on how the Query Optimizer chooses which type of aggregate function to apply. But let’s take a look at SQL Server Integration Services. SSIS gives us a Aggregate transformation for use in Data Flow Tasks, but it’s described as Blocking. The definitive article on Performance Tuning SSIS uses Sort and Aggregate as examples of Blocking Transformations. I’ve just shown you that Aggregate operations used by the Query Optimizer are not always blocking, but that the SSIS Aggregate component is an example of a blocking transformation. But is it always the case? After all, there are plenty of SSIS Performance Tuning talks out there that describe the value of sorted data in Data Flow Tasks, describing the IsSorted property that can be set through the Advanced Editor of your Source component. And so I set about testing the Aggregate transformation in SSIS, to prove for sure whether providing Sorted data would let the Aggregate transform behave like a Stream Aggregate. (Of course, I knew the answer already, but it helps to be able to demonstrate these things). A query that will produce a million rows in order was in order. Let me rephrase. I used a query which produced the numbers from 1 to 1000000, in a single field, ordered. The IsSorted flag was set on the source output, with the only column as SortKey 1. Performing an Aggregate function over this (counting the number of rows per distinct number) should produce an additional column with 1 in it. If this were being done in T-SQL, the ordered data would allow a Stream Aggregate to be used. In fact, if the Query Optimizer saw that the field had a Unique Index on it, it would be able to skip the Aggregate function completely, and just insert the value 1. This is a shortcut I wouldn’t be expecting from SSIS, but certainly the Stream behaviour would be nice. Unfortunately, it’s not the case. As you can see from the screenshots above, the data is pouring into the Aggregate function, and not being released until all million rows have been seen. It’s not doing a Stream Aggregate at all. This is expected behaviour. (I put that in bold, because I want you to realise this.) An SSIS transformation is a piece of code that runs. It’s a physical operation. When you write T-SQL and ask for an aggregation to be done, it’s a logical operation. The physical operation is either a Stream Aggregate or a Hash Match. In SSIS, you’re telling the system that you want a generic Aggregation, that will have to work with whatever data is passed in. I’m not saying that it wouldn’t be possible to make a sometimes-blocking aggregation component in SSIS. A Custom Component could be created which could detect whether the SortKeys columns of the input matched the Grouping columns of the Aggregation, and either call the blocking code or the non-blocking code as appropriate. One day I’ll make one of those, and publish it on my blog. I’ve done it before with a Script Component, but as Script components are single-use, I was able to handle the data knowing everything about my data flow already. As per my previous post – there are a lot of aspects in which tuning SSIS and tuning execution plans use similar concepts. In both situations, it really helps to have a feel for what’s going on behind the scenes. Considering whether an operation is blocking or not is extremely relevant to performance, and that it’s not always obvious from the surface. In a future post, I’ll show the impact of blocking v non-blocking and synchronous v asynchronous components in SSIS, using some of LobsterPot’s Script Components and Custom Components as examples. When I get that sorted, I’ll make a Stream Aggregate component available for download.

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  • The blocking nature of aggregates

    - by Rob Farley
    I wrote a post recently about how query tuning isn’t just about how quickly the query runs – that if you have something (such as SSIS) that is consuming your data (and probably introducing a bottleneck), then it might be more important to have a query which focuses on getting the first bit of data out. You can read that post here.  In particular, we looked at two operators that could be used to ensure that a query returns only Distinct rows. and The Sort operator pulls in all the data, sorts it (discarding duplicates), and then pushes out the remaining rows. The Hash Match operator performs a Hashing function on each row as it comes in, and then looks to see if it’s created a Hash it’s seen before. If not, it pushes the row out. The Sort method is quicker, but has to wait until it’s gathered all the data before it can do the sort, and therefore blocks the data flow. But that was my last post. This one’s a bit different. This post is going to look at how Aggregate functions work, which ties nicely into this month’s T-SQL Tuesday. I’ve frequently explained about the fact that DISTINCT and GROUP BY are essentially the same function, although DISTINCT is the poorer cousin because you have less control over it, and you can’t apply aggregate functions. Just like the operators used for Distinct, there are different flavours of Aggregate operators – coming in blocking and non-blocking varieties. The example I like to use to explain this is a pile of playing cards. If I’m handed a pile of cards and asked to count how many cards there are in each suit, it’s going to help if the cards are already ordered. Suppose I’m playing a game of Bridge, I can easily glance at my hand and count how many there are in each suit, because I keep the pile of cards in order. Moving from left to right, I could tell you I have four Hearts in my hand, even before I’ve got to the end. By telling you that I have four Hearts as soon as I know, I demonstrate the principle of a non-blocking operation. This is known as a Stream Aggregate operation. It requires input which is sorted by whichever columns the grouping is on, and it will release a row as soon as the group changes – when I encounter a Spade, I know I don’t have any more Hearts in my hand. Alternatively, if the pile of cards are not sorted, I won’t know how many Hearts I have until I’ve looked through all the cards. In fact, to count them, I basically need to put them into little piles, and when I’ve finished making all those piles, I can count how many there are in each. Because I don’t know any of the final numbers until I’ve seen all the cards, this is blocking. This performs the aggregate function using a Hash Match. Observant readers will remember this from my Distinct example. You might remember that my earlier Hash Match operation – used for Distinct Flow – wasn’t blocking. But this one is. They’re essentially doing a similar operation, applying a Hash function to some data and seeing if the set of values have been seen before, but before, it needs more information than the mere existence of a new set of values, it needs to consider how many of them there are. A lot is dependent here on whether the data coming out of the source is sorted or not, and this is largely determined by the indexes that are being used. If you look in the Properties of an Index Scan, you’ll be able to see whether the order of the data is required by the plan. A property called Ordered will demonstrate this. In this particular example, the second plan is significantly faster, but is dependent on having ordered data. In fact, if I force a Stream Aggregate on unordered data (which I’m doing by telling it to use a different index), a Sort operation is needed, which makes my plan a lot slower. This is all very straight-forward stuff, and information that most people are fully aware of. I’m sure you’ve all read my good friend Paul White (@sql_kiwi)’s post on how the Query Optimizer chooses which type of aggregate function to apply. But let’s take a look at SQL Server Integration Services. SSIS gives us a Aggregate transformation for use in Data Flow Tasks, but it’s described as Blocking. The definitive article on Performance Tuning SSIS uses Sort and Aggregate as examples of Blocking Transformations. I’ve just shown you that Aggregate operations used by the Query Optimizer are not always blocking, but that the SSIS Aggregate component is an example of a blocking transformation. But is it always the case? After all, there are plenty of SSIS Performance Tuning talks out there that describe the value of sorted data in Data Flow Tasks, describing the IsSorted property that can be set through the Advanced Editor of your Source component. And so I set about testing the Aggregate transformation in SSIS, to prove for sure whether providing Sorted data would let the Aggregate transform behave like a Stream Aggregate. (Of course, I knew the answer already, but it helps to be able to demonstrate these things). A query that will produce a million rows in order was in order. Let me rephrase. I used a query which produced the numbers from 1 to 1000000, in a single field, ordered. The IsSorted flag was set on the source output, with the only column as SortKey 1. Performing an Aggregate function over this (counting the number of rows per distinct number) should produce an additional column with 1 in it. If this were being done in T-SQL, the ordered data would allow a Stream Aggregate to be used. In fact, if the Query Optimizer saw that the field had a Unique Index on it, it would be able to skip the Aggregate function completely, and just insert the value 1. This is a shortcut I wouldn’t be expecting from SSIS, but certainly the Stream behaviour would be nice. Unfortunately, it’s not the case. As you can see from the screenshots above, the data is pouring into the Aggregate function, and not being released until all million rows have been seen. It’s not doing a Stream Aggregate at all. This is expected behaviour. (I put that in bold, because I want you to realise this.) An SSIS transformation is a piece of code that runs. It’s a physical operation. When you write T-SQL and ask for an aggregation to be done, it’s a logical operation. The physical operation is either a Stream Aggregate or a Hash Match. In SSIS, you’re telling the system that you want a generic Aggregation, that will have to work with whatever data is passed in. I’m not saying that it wouldn’t be possible to make a sometimes-blocking aggregation component in SSIS. A Custom Component could be created which could detect whether the SortKeys columns of the input matched the Grouping columns of the Aggregation, and either call the blocking code or the non-blocking code as appropriate. One day I’ll make one of those, and publish it on my blog. I’ve done it before with a Script Component, but as Script components are single-use, I was able to handle the data knowing everything about my data flow already. As per my previous post – there are a lot of aspects in which tuning SSIS and tuning execution plans use similar concepts. In both situations, it really helps to have a feel for what’s going on behind the scenes. Considering whether an operation is blocking or not is extremely relevant to performance, and that it’s not always obvious from the surface. In a future post, I’ll show the impact of blocking v non-blocking and synchronous v asynchronous components in SSIS, using some of LobsterPot’s Script Components and Custom Components as examples. When I get that sorted, I’ll make a Stream Aggregate component available for download.

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  • Someone using my website for Email and significant increase in spam

    - by Joy
    Let me give you the background in context so that you know the full story. Last summer my web guy (he put my website together) got in a fight with someone who attempted to register on my site using the name of my company as part of his user name. I was not aware of this at all until it had escalated dramatically. I don't know why my web guy was so unprofessional in his response to this person. I really don't know him - met him via SCORE and have never met in person. He is a vendor. Anyway, this guy who got into it with my web guy then threatened to do all he could to hurt my business and said he was internet savvy, etc. So, nothing seemed to happen for a while then not long ago this guy attempted to send me a friend request on Linkedin. After his behavior I declined it. Shortly afterwards I began seeing a dramatic increase in spammers posting comments on the blog part of my site. Just lately I have been receiving Emails from a variety of names but all with the "@___" that I own - for my business. I had additional security added so now they have to register in order to comment on my blog and I am seeing a lot of registration attempts from the same (and similar) IP addresses with bogus names and weird Email addresses being blocked. So, it is not creating more work as it is all automatic. The Email addresses are of more concern. Is there a way to identify a person through an IP address or a place to report the behavior or the Email usage? This guy lives in South Carolina so he is not overseas. Any help/advice you can provide will be greatly appreciated. Thanks Joy

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  • Virtualhost entries gets over-written when apache httpd.conf is rebuilt

    - by Amitabh
    Background: We have been trying to get a wildcard SSL working on multiple sub domains on a single dedicated address.. We have two sub domains next.my-personal-website.com and blog.my-personal-website.com Part of our strategy has been to edit the httpd.conf and add the NameVirtualHost xx.xx.144.72:443 directive and the virtualhost entries for port 443 for the subdomains there. This works good if we just edit the httpd.conf, add the entries, save it and restart the apache. The problem: But if we add a new sub domain from cpanel or we run the # /usr/local/cpanel/bin/apache_conf_distiller --update # /scripts/rebuildhttpdconf the virtualhost entries that we added manually are no more there in the newly generated httpd.conf file. Only the virtualhost entry for the main domain for port 443 that was there before we made edits to the httpd.conf is there(assuming we are not discussing virtualhost entries for port 80). I understand we need to put the new virtualhost entries in some include files as mentioned here in the cpanel documentation. But am not sure where to. So the question would be where do I put the NameVirtualHost xx.xx.144.72:443 directive and the two virtualhost directive for port 443, so that they are not overwritten when httpd.conf is rebuilt/regenerated later. Virtualhost entries: The two virtualhost entries for the subdomains are: <VirtualHost xx.xx.144.72:443> ServerName next.my-personal-website.com ServerAlias www.next.my-personal-website.com DocumentRoot /home/myguardi/public_html/next.my-personal-website.com ServerAdmin [email protected] UseCanonicalName On CustomLog /usr/local/apache/domlogs/next.my-personal-website.com combined CustomLog /usr/local/apache/domlogs/next.my-personal-website.com-bytes_log "%{%s}t %I .\n%{%s}t %O ." ## User myguardi # Needed for Cpanel::ApacheConf <IfModule mod_suphp.c> suPHP_UserGroup myguardi myguardi </IfModule> <IfModule !mod_disable_suexec.c> SuexecUserGroup myguardi myguardi </IfModule> ScriptAlias /cgi-bin/ /home/myguardi/public_html/next.my-personal-website.com/cgi-bin/ SSLEngine on SSLCertificateFile /etc/ssl/certs/my-personal-website.com.crt SSLCertificateKeyFile /etc/ssl/private/my-personal-website.com.key SSLCACertificateFile /etc/ssl/certs/my-personal-website.com.cabundle CustomLog /usr/local/apache/domlogs/next.my-personal-website.com-ssl_log combined SetEnvIf User-Agent ".*MSIE.*" nokeepalive ssl-unclean-shutdown <Directory "/home/myguardi/public_html/cgi-bin"> SSLOptions +StdEnvVars </Directory> and <VirtualHost xx.xx.144.72:443> ServerName blog.my-personal-website.com ServerAlias www.blog.my-personal-website.com DocumentRoot /home/myguardi/public_html/blog.my-personal-website.com ServerAdmin [email protected] UseCanonicalName On CustomLog /usr/local/apache/domlogs/blog.my-personal-website.com combined CustomLog /usr/local/apache/domlogs/blog.my-personal-website.com-bytes_log "%{%s}t %I .\n%{%s}t %O ." ## User myguardi # Needed for Cpanel::ApacheConf <IfModule mod_suphp.c> suPHP_UserGroup myguardi myguardi </IfModule> <IfModule !mod_disable_suexec.c> SuexecUserGroup myguardi myguardi </IfModule> ScriptAlias /cgi-bin/ /home/myguardi/public_html/blog.my-personal-website.com/cgi-bin/ SSLEngine on SSLCertificateFile /etc/ssl/certs/my-personal-website.com.crt SSLCertificateKeyFile /etc/ssl/private/my-personal-website.com.key SSLCACertificateFile /etc/ssl/certs/my-personal-website.com.cabundle CustomLog /usr/local/apache/domlogs/blog.my-personal-website.com-ssl_log combined SetEnvIf User-Agent ".*MSIE.*" nokeepalive ssl-unclean-shutdown <Directory "/home/myguardi/public_html/cgi-bin"> SSLOptions +StdEnvVars </Directory> and the automatically generated virtualhost entry for the main domain for port 443 is <VirtualHost xx.xx.144.72:443> ServerName my-personal-website.com ServerAlias www.my-personal-website.com DocumentRoot /home/myguardi/public_html ServerAdmin [email protected] UseCanonicalName Off CustomLog /usr/local/apache/domlogs/my-personal-website.com combined CustomLog /usr/local/apache/domlogs/my-personal-website.com-bytes_log "%{%s}t %I .\n%{%s}t %O ." ## User myguardi # Needed for Cpanel::ApacheConf <IfModule mod_suphp.c> suPHP_UserGroup myguardi myguardi </IfModule> <IfModule !mod_disable_suexec.c> SuexecUserGroup myguardi myguardi </IfModule> ScriptAlias /cgi-bin/ /home/myguardi/public_html/cgi-bin/ SSLEngine on SSLCertificateFile /etc/ssl/certs/my-personal-website.com.crt SSLCertificateKeyFile /etc/ssl/private/my-personal-website.com.key SSLCACertificateFile /etc/ssl/certs/my-personal-website.com.cabundle CustomLog /usr/local/apache/domlogs/my-personal-website.com-ssl_log combined SetEnvIf User-Agent ".*MSIE.*" nokeepalive ssl-unclean-shutdown <Directory "/home/myguardi/public_html/cgi-bin"> SSLOptions +StdEnvVars </Directory> # To customize this VirtualHost use an include file at the following location # Include "/usr/local/apache/conf/userdata/ssl/2/myguardi/my-personal-website.com/*.conf" I really appreciate if somebody can tell me how to proceed on this. Thank you. Update: Include directives present are: `Include "/usr/local/apache/conf/includes/pre_main_global.conf" Include "/usr/local/apache/conf/includes/pre_main_2.conf" Include "/usr/local/apache/conf/php.conf" Include "/usr/local/apache/conf/includes/errordocument.conf" Include "/usr/local/apache/conf/modsec2.conf" Include "/usr/local/apache/conf/includes/pre_virtualhost_global.conf" Include "/usr/local/apache/conf/includes/pre_virtualhost_2.conf" ` These are the entries that are generated before any virtualhost entry is defined. Towards the end of the httpd.conf file , the following two entries are added Include "/usr/local/apache/conf/includes/post_virtualhost_global.conf" Include "/usr/local/apache/conf/includes/post_virtualhost_2.conf" The older httpd.conf file before we added the virtualhost entries for sub domains for port 443 can be viewed here

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  • Extreme Performance and Scale Delivered by SOA on Oracle Exalogic

    - by J Swaroop
    Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-family:"Calibri","sans-serif"; mso-ascii- mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi- mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-family:"Calibri","sans-serif"; mso-ascii- mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi- mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Demands to incorporate internet-scale applications, data, and social media traffic with existing IT infrastructure require extreme availability, reliability, and scalability. In this session on industrial-strength SOA, learn how Oracle Exalogic and Oracle Exadata engineered systems address these requirements. Topics covered: (1) how SOA and BPM benefit from “hardware and software engineered for each other,” (2) how Oracle Exadata provides the data tier with unparalleled scalability and performance for SOA and BPM running on Oracle Exalogic (3) customer case studies (4) best practices and topology guidelines (5) information on tools that help operate, manage, provision, and deploy—to help reduce overall TCO. Extreme engineering at its best! Session details: 10/2/12 (Tuesday) 11:45 AM - Moscone South -308

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  • Have You Heard About Project Lucy?

    - by KKline
    Lucy, You Got Some 'Splainin to Do!' Quest Software's latest community initiative, Windows Azure-based Project Lucy, has debuted! Project Lucy is part infrastructure analytics, part social media experiment, and part performance data warehouse. The best things about Project Lucy include: It’s Free - just like our SQLServerPedia website, Project Lucy is free to anyone who wants to upload a trace file It’s 1oo% web-based - you don’t have to download or maintain anything and updates roll out seamlessly,...(read more)

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