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  • Is it possible to repair a Cisco 3500 XL (3548) switch with POST Error messages?

    - by Alex
    I've got an old Cisco 3500 XL, and it seems to have hardware issues. I've loaded the latest IOS and cleared all config. Does anyone have any experience fixing the switch core? I'm a reasonably competent SMD solderer, can I replace/reflow some chips? I've checked the power supply voltages and it's all within tolerance, and no visible signs of any component damage. Some chips are hot to the touch. I understand that these were EOL as of 2007, but should have a lifetime warranty for the electronics. I don't have a Cisco support contract, so I can't file a ticket. What should I do? Console output: switch: dir flash: Directory of flash:/ 2 -rwx 1811584 <date> c3500xl-c3h2s-mz.120-5.WC17.bin 1799680 bytes available (1812992 bytes used) switch: boot Loading "flash:c3500xl-c3h2s-mz.120-5.WC17.bin"...################################################################################################################################################################################### File "flash:c3500xl-c3h2s-mz.120-5.WC17.bin" uncompressed and installed, entry point: 0x3000 executing... Restricted Rights Legend Use, duplication, or disclosure by the Government is subject to restrictions as set forth in subparagraph (c) of the Commercial Computer Software - Restricted Rights clause at FAR sec. 52.227-19 and subparagraph (c) (1) (ii) of the Rights in Technical Data and Computer Software clause at DFARS sec. 252.227-7013. cisco Systems, Inc. 170 West Tasman Drive San Jose, California 95134-1706 Cisco Internetwork Operating System Software IOS (tm) C3500XL Software (C3500XL-C3H2S-M), Version 12.0(5)WC17, RELEASE SOFTWARE (fc1) Copyright (c) 1986-2007 by cisco Systems, Inc. Compiled Tue 13-Feb-07 15:04 by antonino Image text-base: 0x00003000, data-base: 0x00352924 Initializing C3500XL flash... flashfs[1]: 1 files, 1 directories flashfs[1]: 0 orphaned files, 0 orphaned directories flashfs[1]: Total bytes: 3612672 flashfs[1]: Bytes used: 1812992 flashfs[1]: Bytes available: 1799680 flashfs[1]: flashfs fsck took 3 seconds. flashfs[1]: Initialization complete. ...done Initializing C3500XL flash. C3500XL POST: System Board Test: Passed C3500XL POST: Daughter Card Test: Passed C3500XL POST: CPU Buffer Test: Passed C3500XL POST: CPU Notify RAM Test: Passed C3500XL POST: CPU Interface Test: Passed C3500XL POST: Testing Switch Core: Passed Error with Switch Core BIST test Phase 0. Returns: Test Complete Low : 0x0FFFFFFF, Test Complete High : 0xFFFFFFFE Test Phase Low : 0x00000040, Test Phase High : 0x00000000 Test Phase Third : 0x00000000, Test Complete Third : 0x000001F8 C3500XL POST FAILURE: Testing Switch Core: Failed C3500XL POST FAILURE: Testing Buffer Table: Failed C3500XL POST FAILURE: Data Buffer Test: Failed C3500XL POST FAILURE: Configuring Switch Parameters: Failed C3500XL POST FAILURE: Switch Core BIST failed. C3500XL POST FAILURE: Cannot test Modules due to failure of Switch Core POST Del Mar Failure (0th Del Mar): req system failed to init C3500XL POST FAILURE: C3500XL POST FAILURE: ATM: required system failed to init C3500XL POST: Ethernet Controller Test: Passed C3500XL POST FAILURE: MII Test: Failed C3500XL POST FAILURE: Error waiting for Ethernet Controller and SW_PARAMS C3500XL POST FAILURE: Initialization/POST failed C3500XL POST FAILURE: AT: Failing because system POST failed Exception (8192)! Debug Exception (Could be NULL pointer dereference) CPU Register Context: Vector = 0x00002000 PC = 0x000F36F4 MSR = 0x00029200 CR = 0x22000024 LR = 0x000F6964 CTR = 0x001DE46C XER = 0x00000000 R0 = 0x00000000 R1 = 0x004E2580 R2 = 0x00000000 R3 = 0x00000000 R4 = 0x00000001 R5 = 0x00000000 R6 = 0x004E2718 R7 = 0x004E2718 R8 = 0x00000008 R9 = 0x00000000 R10 = 0x0000FFFF R11 = 0x00480000 R12 = 0x42000024 R13 = 0x00000000 R14 = 0x00000000 R15 = 0x00000000 R16 = 0x00000000 R17 = 0x00000000 R18 = 0x00000000 R19 = 0x00000000 R20 = 0x00000000 R21 = 0x00000000 R22 = 0x00000000 R23 = 0x00000000 R24 = 0x00000000 R25 = 0x00000020 R26 = 0x004E2718 R27 = 0x004E2718 R28 = 0x00000020 R29 = 0x00002513 R30 = 0x00000001 R31 = 0x00000000 Stack trace: PC = 0x000F36F4, SP = 0x004E2580 Frame 00: SP = 0x004E25A0 PC = 0x40000016 Frame 01: SP = 0x004E2618 PC = 0x000F6964 Frame 02: SP = 0x004E26A8 PC = 0x000F76DC Frame 03: SP = 0x004E26C8 PC = 0x000E8114 Frame 04: SP = 0x004E26F0 PC = 0x001F5BF8 Frame 05: SP = 0x004E2710 PC = 0x001F5CF4 Frame 06: SP = 0x004E2748 PC = 0x0023F4DC Frame 07: SP = 0x004E2750 PC = 0x0023E650 Frame 08: SP = 0x004E27C8 PC = 0x0023E89C Frame 09: SP = 0x004E27E0 PC = 0x0028AF34 Frame 10: SP = 0x004E27E8 PC = 0x001E38F8 Frame 11: SP = 0x004E2808 PC = 0x001E39A8 Frame 12: SP = 0x004E2820 PC = 0x0014E220 Frame 13: SP = 0x004E28C8 PC = 0x0014E39C Frame 14: SP = 0x00000000 PC = 0x001EB510

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  • Tip/Trick: Fix Common SEO Problems Using the URL Rewrite Extension

    - by ScottGu
    Search engine optimization (SEO) is important for any publically facing web-site.  A large % of traffic to sites now comes directly from search engines, and improving your site’s search relevancy will lead to more users visiting your site from search engine queries.  This can directly or indirectly increase the money you make through your site. This blog post covers how you can use the free Microsoft URL Rewrite Extension to fix a bunch of common SEO problems that your site might have.  It takes less than 15 minutes (and no code changes) to apply 4 simple URL Rewrite rules to your site, and in doing so cause search engines to drive more visitors and traffic to your site.  The techniques below work equally well with both ASP.NET Web Forms and ASP.NET MVC based sites.  They also works with all versions of ASP.NET (and even work with non-ASP.NET content). [In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu] Measuring the SEO of your website with the Microsoft SEO Toolkit A few months ago I blogged about the free SEO Toolkit that we’ve shipped.  This useful tool enables you to automatically crawl/scan your site for SEO correctness, and it then flags any SEO issues it finds.  I highly recommend downloading and using the tool against any public site you work on.  It makes it easy to spot SEO issues you might have in your site, and pinpoint ways to optimize it further. Below is a simple example of a report I ran against one of my sites (www.scottgu.com) prior to applying the URL Rewrite rules I’ll cover later in this blog post:   Search Relevancy and URL Splitting Two of the important things that search engines evaluate when assessing your site’s “search relevancy” are: How many other sites link to your content.  Search engines assume that if a lot of people around the web are linking to your content, then it is likely useful and so weight it higher in relevancy. The uniqueness of the content it finds on your site.  If search engines find that the content is duplicated in multiple places around the Internet (or on multiple URLs on your site) then it is likely to drop the relevancy of the content. One of the things you want to be very careful to avoid when building public facing sites is to not allow different URLs to retrieve the same content within your site.  Doing so will hurt with both of the situations above.  In particular, allowing external sites to link to the same content with multiple URLs will cause your link-count and page-ranking to be split up across those different URLs (and so give you a smaller page rank than what it would otherwise be if it was just one URL).  Not allowing external sites to link to you in different ways sounds easy in theory – but you might wonder what exactly this means in practice and how you avoid it. 4 Really Common SEO Problems Your Sites Might Have Below are 4 really common scenarios that can cause your site to inadvertently expose multiple URLs for the same content.  When this happens external sites linking to yours will end up splitting their page links across multiple URLs - and as a result cause you to have a lower page ranking with search engines than you deserve. SEO Problem #1: Default Document IIS (and other web servers) supports the concept of a “default document”.  This allows you to avoid having to explicitly specify the page you want to serve at either the root of the web-site/application, or within a sub-directory.  This is convenient – but means that by default this content is available via two different publically exposed URLs (which is bad).  For example: http://scottgu.com/ http://scottgu.com/default.aspx SEO Problem #2: Different URL Casings Web developers often don’t realize URLs are case sensitive to search engines on the web.  This means that search engines will treat the following links as two completely different URLs: http://scottgu.com/Albums.aspx http://scottgu.com/albums.aspx SEO Problem #3: Trailing Slashes Consider the below two URLs – they might look the same at first, but they are subtly different. The trailing slash creates yet another situation that causes search engines to treat the URLs as different and so split search rankings: http://scottgu.com http://scottgu.com/ SEO Problem #4: Canonical Host Names Sometimes sites support scenarios where they support a web-site with both a leading “www” hostname prefix as well as just the hostname itself.  This causes search engines to treat the URLs as different and split search rankling: http://scottgu.com/albums.aspx/ http://www.scottgu.com/albums.aspx/ How to Easily Fix these SEO Problems in 10 minutes (or less) using IIS Rewrite If you haven’t been careful when coding your sites, chances are you are suffering from one (or more) of the above SEO problems.  Addressing these issues will improve your search engine relevancy ranking and drive more traffic to your site. The “good news” is that fixing the above 4 issues is really easy using the URL Rewrite Extension.  This is a completely free Microsoft extension available for IIS 7.x (on Windows Server 2008, Windows Server 2008 R2, Windows 7 and Windows Vista).  The great thing about using the IIS Rewrite extension is that it allows you to fix the above problems *without* having to change any code within your applications.  You can easily install the URL Rewrite Extension in under 3 minutes using the Microsoft Web Platform Installer (a free tool we ship that automates setting up web servers and development machines).  Just click the green “Install Now” button on the URL Rewrite Spotlight page to install it on your Windows Server 2008, Windows 7 or Windows Vista machine: Once installed you’ll find that a new “URL Rewrite” icon is available within the IIS 7 Admin Tool: Double-clicking the icon will open up the URL Rewrite admin panel – which will display the list of URL Rewrite rules configured for a particular application or site: Notice that our rewrite rule list above is currently empty (which is the default when you first install the extension).  We can click the “Add Rule…” link button in the top-right of the panel to add and enable new URL Rewriting logic for our site.  Scenario 1: Handling Default Document Scenarios One of the SEO problems I discussed earlier in this post was the scenario where the “default document” feature of IIS causes you to inadvertently expose two URLs for the same content on your site.  For example: http://scottgu.com/ http://scottgu.com/default.aspx We can fix this by adding a new IIS Rewrite rule that automatically redirects anyone who navigates to the second URL to instead go to the first one.  We will setup the HTTP redirect to be a “permanent redirect” – which will indicate to search engines that they should follow the redirect and use the new URL they are redirected to as the identifier of the content they retrieve.  Let’s look at how we can create such a rule.  We’ll begin by clicking the “Add Rule” link in the screenshot above.  This will cause the below dialog to display: We’ll select the “Blank Rule” template within the “Inbound rules” section to create a new custom URL Rewriting rule.  This will display an empty pane like below: Don’t worry – setting up the above rule is easy.  The following 4 steps explain how to do so: Step 1: Name the Rule Our first step will be to name the rule we are creating.  Naming it with a descriptive name will make it easier to find and understand later.  Let’s name this rule our “Default Document URL Rewrite” rule: Step 2: Setup the Regular Expression that Matches this Rule Our second step will be to specify a regular expression filter that will cause this rule to execute when an incoming URL matches the regex pattern.   Don’t worry if you aren’t good with regular expressions - I suck at them too. The trick is to know someone who is good at them or copy/paste them from a web-site.  Below we are going to specify the following regular expression as our pattern rule: (.*?)/?Default\.aspx$ This pattern will match any URL string that ends with Default.aspx. The "(.*?)" matches any preceding character zero or more times. The "/?" part says to match the slash symbol zero or one times. The "$" symbol at the end will ensure that the pattern will only match strings that end with Default.aspx.  Combining all these regex elements allows this rule to work not only for the root of your web site (e.g. http://scottgu.com/default.aspx) but also for any application or subdirectory within the site (e.g. http://scottgu.com/photos/default.aspx.  Because the “ignore case” checkbox is selected it will match both “Default.aspx” as well as “default.aspx” within the URL.   One nice feature built-into the rule editor is a “Test pattern” button that you can click to bring up a dialog that allows you to test out a few URLs with the rule you are configuring: Above I've added a “products/default.aspx” URL and clicked the “Test” button.  This will give me immediate feedback on whether the rule will execute for it.  Step 3: Setup a Permanent Redirect Action We’ll then setup an action to occur when our regular expression pattern matches the incoming URL: In the dialog above I’ve changed the “Action Type” drop down to be a “Redirect” action.  The “Redirect Type” will be a HTTP 301 Permanent redirect – which means search engines will follow it. I’ve also set the “Redirect URL” property to be: {R:1}/ This indicates that we want to redirect the web client requesting the original URL to a new URL that has the originally requested URL path - minus the "Default.aspx" in it.  For example, requests for http://scottgu.com/default.aspx will be redirected to http://scottgu.com/, and requests for http://scottgu.com/photos/default.aspx will be redirected to http://scottgu.com/photos/ The "{R:N}" regex construct, where N >= 0, is called a back-reference and N is the back-reference index. In the case of our pattern "(.*?)/?Default\.aspx$", if the input URL is "products/Default.aspx" then {R:0} will contain "products/Default.aspx" and {R:1} will contain "products".  We are going to use this {R:1}/ value to be the URL we redirect users to.  Step 4: Apply and Save the Rule Our final step is to click the “Apply” button in the top right hand of the IIS admin tool – which will cause the tool to persist the URL Rewrite rule into our application’s root web.config file (under a <system.webServer/rewrite> configuration section): <configuration>     <system.webServer>         <rewrite>             <rules>                 <rule name="Default Document" stopProcessing="true">                     <match url="(.*?)/?Default\.aspx$" />                     <action type="Redirect" url="{R:1}/" />                 </rule>             </rules>         </rewrite>     </system.webServer> </configuration> Because IIS 7.x and ASP.NET share the same web.config files, you can actually just copy/paste the above code into your web.config files using Visual Studio and skip the need to run the admin tool entirely.  This also makes adding/deploying URL Rewrite rules with your ASP.NET applications really easy. Step 5: Try the Rule Out Now that we’ve saved the rule, let’s try it out on our site.  Try the following two URLs on my site: http://scottgu.com/ http://scottgu.com/default.aspx Notice that the second URL automatically redirects to the first one.  Because it is a permanent redirect, search engines will follow the URL and should update the page ranking of http://scottgu.com to include links to http://scottgu.com/default.aspx as well. Scenario 2: Different URL Casing Another common SEO problem I discussed earlier in this post is that URLs are case sensitive to search engines on the web.  This means that search engines will treat the following links as two completely different URLs: http://scottgu.com/Albums.aspx http://scottgu.com/albums.aspx We can fix this by adding a new IIS Rewrite rule that automatically redirects anyone who navigates to the first URL to instead go to the second (all lower-case) one.  Like before, we will setup the HTTP redirect to be a “permanent redirect” – which will indicate to search engines that they should follow the redirect and use the new URL they are redirected to as the identifier of the content they retrieve. To create such a rule we’ll click the “Add Rule” link in the URL Rewrite admin tool again.  This will cause the “Add Rule” dialog to appear again: Unlike the previous scenario (where we created a “Blank Rule”), with this scenario we can take advantage of a built-in “Enforce lowercase URLs” rule template.  When we click the “ok” button we’ll see the following dialog which asks us if we want to create a rule that enforces the use of lowercase letters in URLs: When we click the “Yes” button we’ll get a pre-written rule that automatically performs a permanent redirect if an incoming URL has upper-case characters in it – and automatically send users to a lower-case version of the URL: We can click the “Apply” button to use this rule “as-is” and have it apply to all incoming URLs to our site.  Because my www.scottgu.com site uses ASP.NET Web Forms, I’m going to make one small change to the rule we generated above – which is to add a condition that will ensure that URLs to ASP.NET’s built-in “WebResource.axd” handler are excluded from our case-sensitivity URL Rewrite logic.  URLs to the WebResource.axd handler will only come from server-controls emitted from my pages – and will never be linked to from external sites.  While my site will continue to function fine if we redirect these URLs to automatically be lower-case – doing so isn’t necessary and will add an extra HTTP redirect to many of my pages.  The good news is that adding a condition that prevents my URL Rewriting rule from happening with certain URLs is easy.  We simply need to expand the “Conditions” section of the form above We can then click the “Add” button to add a condition clause.  This will bring up the “Add Condition” dialog: Above I’ve entered {URL} as the Condition input – and said that this rule should only execute if the URL does not match a regex pattern which contains the string “WebResource.axd”.  This will ensure that WebResource.axd URLs to my site will be allowed to execute just fine without having the URL be re-written to be all lower-case. Note: If you have static resources (like references to .jpg, .css, and .js files) within your site that currently use upper-case characters you’ll probably want to add additional condition filter clauses so that URLs to them also don’t get redirected to be lower-case (just add rules for patterns like .jpg, .gif, .js, etc).  Your site will continue to work fine if these URLs get redirected to be lower case (meaning the site won’t break) – but it will cause an extra HTTP redirect to happen on your site for URLs that don’t need to be redirected for SEO reasons.  So setting up a condition clause makes sense to add. When I click the “ok” button above and apply our lower-case rewriting rule the admin tool will save the following additional rule to our web.config file: <configuration>     <system.webServer>         <rewrite>             <rules>                 <rule name="Default Document" stopProcessing="true">                     <match url="(.*?)/?Default\.aspx$" />                     <action type="Redirect" url="{R:1}/" />                 </rule>                 <rule name="Lower Case URLs" stopProcessing="true">                     <match url="[A-Z]" ignoreCase="false" />                     <conditions logicalGrouping="MatchAll" trackAllCaptures="false">                         <add input="{URL}" pattern="WebResource.axd" negate="true" />                     </conditions>                     <action type="Redirect" url="{ToLower:{URL}}" />                 </rule>             </rules>         </rewrite>     </system.webServer> </configuration> Try the Rule Out Now that we’ve saved the rule, let’s try it out on our site.  Try the following two URLs on my site: http://scottgu.com/Albums.aspx http://scottgu.com/albums.aspx Notice that the first URL (which has a capital “A”) automatically does a redirect to a lower-case version of the URL.  Scenario 3: Trailing Slashes Another common SEO problem I discussed earlier in this post is the scenario of trailing slashes within URLs.  The trailing slash creates yet another situation that causes search engines to treat the URLs as different and so split search rankings: http://scottgu.com http://scottgu.com/ We can fix this by adding a new IIS Rewrite rule that automatically redirects anyone who navigates to the first URL (that does not have a trailing slash) to instead go to the second one that does.  Like before, we will setup the HTTP redirect to be a “permanent redirect” – which will indicate to search engines that they should follow the redirect and use the new URL they are redirected to as the identifier of the content they retrieve.  To create such a rule we’ll click the “Add Rule” link in the URL Rewrite admin tool again.  This will cause the “Add Rule” dialog to appear again: The URL Rewrite admin tool has a built-in “Append or remove the trailing slash symbol” rule template.  When we select it and click the “ok” button we’ll see the following dialog which asks us if we want to create a rule that automatically redirects users to a URL with a trailing slash if one isn’t present: Like within our previous lower-casing rewrite rule we’ll add one additional condition clause that will exclude WebResource.axd URLs from being processed by this rule.  This will avoid an unnecessary redirect for happening for those URLs. When we click the “OK” button we’ll get a pre-written rule that automatically performs a permanent redirect if the URL doesn’t have a trailing slash – and if the URL is not processed by either a directory or a file.  This will save the following additional rule to our web.config file: <configuration>     <system.webServer>         <rewrite>             <rules>                 <rule name="Default Document" stopProcessing="true">                     <match url="(.*?)/?Default\.aspx$" />                     <action type="Redirect" url="{R:1}/" />                 </rule>                 <rule name="Lower Case URLs" stopProcessing="true">                     <match url="[A-Z]" ignoreCase="false" />                     <conditions logicalGrouping="MatchAll" trackAllCaptures="false">                         <add input="{URL}" pattern="WebResource.axd" negate="true" />                     </conditions>                     <action type="Redirect" url="{ToLower:{URL}}" />                 </rule>                 <rule name="Trailing Slash" stopProcessing="true">                     <match url="(.*[^/])$" />                     <conditions logicalGrouping="MatchAll" trackAllCaptures="false">                         <add input="{REQUEST_FILENAME}" matchType="IsDirectory" negate="true" />                         <add input="{REQUEST_FILENAME}" matchType="IsFile" negate="true" />                         <add input="{URL}" pattern="WebResource.axd" negate="true" />                     </conditions>                     <action type="Redirect" url="{R:1}/" />                 </rule>             </rules>         </rewrite>     </system.webServer> </configuration> Try the Rule Out Now that we’ve saved the rule, let’s try it out on our site.  Try the following two URLs on my site: http://scottgu.com http://scottgu.com/ Notice that the first URL (which has no trailing slash) automatically does a redirect to a URL with the trailing slash.  Because it is a permanent redirect, search engines will follow the URL and update the page ranking. Scenario 4: Canonical Host Names The final SEO problem I discussed earlier are scenarios where a site works with both a leading “www” hostname prefix as well as just the hostname itself.  This causes search engines to treat the URLs as different and split search rankling: http://www.scottgu.com/albums.aspx http://scottgu.com/albums.aspx We can fix this by adding a new IIS Rewrite rule that automatically redirects anyone who navigates to the first URL (that has a www prefix) to instead go to the second URL.  Like before, we will setup the HTTP redirect to be a “permanent redirect” – which will indicate to search engines that they should follow the redirect and use the new URL they are redirected to as the identifier of the content they retrieve.  To create such a rule we’ll click the “Add Rule” link in the URL Rewrite admin tool again.  This will cause the “Add Rule” dialog to appear again: The URL Rewrite admin tool has a built-in “Canonical domain name” rule template.  When we select it and click the “ok” button we’ll see the following dialog which asks us if we want to create a redirect rule that automatically redirects users to a primary host name URL: Above I’m entering the primary URL address I want to expose to the web: scottgu.com.  When we click the “OK” button we’ll get a pre-written rule that automatically performs a permanent redirect if the URL has another leading domain name prefix.  This will save the following additional rule to our web.config file: <configuration>     <system.webServer>         <rewrite>             <rules>                 <rule name="Cannonical Hostname">                     <match url="(.*)" />                     <conditions logicalGrouping="MatchAll" trackAllCaptures="false">                         <add input="{HTTP_HOST}" pattern="^scottgu\.com$" negate="true" />                     </conditions>                     <action type="Redirect" url="http://scottgu.com/{R:1}" />                 </rule>                 <rule name="Default Document" stopProcessing="true">                     <match url="(.*?)/?Default\.aspx$" />                     <action type="Redirect" url="{R:1}/" />                 </rule>                 <rule name="Lower Case URLs" stopProcessing="true">                     <match url="[A-Z]" ignoreCase="false" />                     <conditions logicalGrouping="MatchAll" trackAllCaptures="false">                         <add input="{URL}" pattern="WebResource.axd" negate="true" />                     </conditions>                     <action type="Redirect" url="{ToLower:{URL}}" />                 </rule>                 <rule name="Trailing Slash" stopProcessing="true">                     <match url="(.*[^/])$" />                     <conditions logicalGrouping="MatchAll" trackAllCaptures="false">                         <add input="{REQUEST_FILENAME}" matchType="IsDirectory" negate="true" />                         <add input="{REQUEST_FILENAME}" matchType="IsFile" negate="true" />                         <add input="{URL}" pattern="WebResource.axd" negate="true" />                     </conditions>                     <action type="Redirect" url="{R:1}/" />                 </rule>             </rules>         </rewrite>     </system.webServer> </configuration> Try the Rule Out Now that we’ve saved the rule, let’s try it out on our site.  Try the following two URLs on my site: http://www.scottgu.com/albums.aspx http://scottgu.com/albums.aspx Notice that the first URL (which has the “www” prefix) now automatically does a redirect to the second URL which does not have the www prefix.  Because it is a permanent redirect, search engines will follow the URL and update the page ranking. 4 Simple Rules for Improved SEO The above 4 rules are pretty easy to setup and should take less than 15 minutes to configure on existing sites you already have.  The beauty of using a solution like the URL Rewrite Extension is that you can take advantage of it without having to change code within your web-site – and without having to break any existing links already pointing at your site.  Users who follow existing links will be automatically redirected to the new URLs you wish to publish.  And search engines will start to give your site a higher search relevancy ranking – which will list your site higher in search results and drive more traffic to it. Customizing your URL Rewriting rules further is easy to-do either by editing the web.config file directly, or alternatively, just double click the URL Rewrite icon within the IIS 7.x admin tool and it will list all the active rules for your web-site or application: Clicking any of the rules above will open the rules editor back up and allow you to tweak/customize/save them further. Summary Measuring and improving SEO is something every developer building a public-facing web-site needs to think about and focus on.  If you haven’t already, download and use the SEO Toolkit to analyze the SEO of your sites today. New URL Routing features in ASP.NET MVC and ASP.NET Web Forms 4 make it much easier to build applications that have more control over the URLs that are published.  Tools like the URL Rewrite Extension that I’ve talked about in this blog post make it much easier to improve the URLs that are published from sites you already have built today – without requiring you to change a lot of code. The URL Rewrite Extension provides a bunch of additional great capabilities – far beyond just SEO - as well.  I’ll be covering these additional capabilities more in future blog posts. Hope this helps, Scott

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  • Deleting MySQL rows causes lock table error

    - by Dave L
    I had a couple million rows to delete but they can't be deleted at once without this error ERROR 1206 (HY000): The total number of locks exceeds the lock table size So I wrote a script to delete 100,000 rows 10,000 at a time. It ran once but when I run it a second time I get the error on the first attempt to delete 10,000. The way I'm trying to delete the 10,000 rows is to use a delete statement that refers to all 2 million rows but I use a limit clause to affect only 10,000. I've tried adding an "unlock tables;" statement to the script before the first delete but that doesn't help. I still get the lock table error on the first delete. Any ideas how I can do this? Is there a way I can tell it NOT to lock records? I can make sure nothing else is accessing the table.

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  • Configuring htaccess to show authentication prompt only for subdomain

    - by Philipp Lenssen
    How do I write the htaccess so that it will only require authentication when on admin.example.com, but not on www.example.com (like by using some if-else clause)? Background: I have a site running in two modes: The admin mode should be reached at something like admin.example.com, whereas the normal mode would be www.example.com -- but both should point to the same directory & scripts within them (the scripts then turn on certain editing features by checking if the script is accessed from the admin subdomain). Edit: I can now see this has been asked and answered at StackOverflow, though I can't get the top answer to work for me...

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  • Multiple columns in a single index versus multiple indexes

    - by Tim Coker
    The short version of my question is what's the difference between three indexes each indexing a single column and one index indexing three columns. Background follows. I'm primarily a programmer but have to do DBA work because we don't have a DBA. I'm evaluating our indexes versus the queries run against a particular table. The table as 3 columns that I'm often filtering against or getting the max value of. Most of the time the queries look like select max(col_a) from table where col_b = 'avalue' or select col_c from table where col_b = 'avalue' and col_a = 'anothervalue' All columns are independently indexed. My question is would I see any difference if I had an index that indexed col_b and col_a together since they can appear in a where clause together?

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  • Implementing a popularity algorithm in Django

    - by TheLizardKing
    I am creating a site similar to reddit and hacker news that has a database of links and votes. I am implementing hacker news' popularity algorithm and things are going pretty swimmingly until it comes to actually gathering up these links and displaying them. The algorithm is simple: Y Combinator's Hacker News: Popularity = (p - 1) / (t + 2)^1.5` Votes divided by age factor. Where` p : votes (points) from users. t : time since submission in hours. p is subtracted by 1 to negate submitter's vote. Age factor is (time since submission in hours plus two) to the power of 1.5.factor is (time since submission in hours plus two) to the power of 1.5. I asked a very similar question over yonder http://stackoverflow.com/questions/1964395/complex-ordering-in-django but instead of contemplating my options I choose one and tried to make it work because that's how I did it with PHP/MySQL but I now know Django does things a lot differently. My models look something (exactly) like this class Link(models.Model): category = models.ForeignKey(Category) user = models.ForeignKey(User) created = models.DateTimeField(auto_now_add = True) modified = models.DateTimeField(auto_now = True) fame = models.PositiveIntegerField(default = 1) title = models.CharField(max_length = 256) url = models.URLField(max_length = 2048) def __unicode__(self): return self.title class Vote(models.Model): link = models.ForeignKey(Link) user = models.ForeignKey(User) created = models.DateTimeField(auto_now_add = True) modified = models.DateTimeField(auto_now = True) karma_delta = models.SmallIntegerField() def __unicode__(self): return str(self.karma_delta) and my view: def index(request): popular_links = Link.objects.select_related().annotate(karma_total = Sum('vote__karma_delta')) return render_to_response('links/index.html', {'links': popular_links}) Now from my previous question, I am trying to implement the algorithm using the sorting function. An answer from that question seems to think I should put the algorithm in the select and sort then. I am going to paginate these results so I don't think I can do the sorting in python without grabbing everything. Any suggestions on how I could efficiently do this? EDIT This isn't working yet but I think it's a step in the right direction: from django.shortcuts import render_to_response from linkett.apps.links.models import * def index(request): popular_links = Link.objects.select_related() popular_links = popular_links.extra( select = { 'karma_total': 'SUM(vote.karma_delta)', 'popularity': '(karma_total - 1) / POW(2, 1.5)', }, order_by = ['-popularity'] ) return render_to_response('links/index.html', {'links': popular_links}) This errors out into: Caught an exception while rendering: column "karma_total" does not exist LINE 1: SELECT ((karma_total - 1) / POW(2, 1.5)) AS "popularity", (S... EDIT 2 Better error? TemplateSyntaxError: Caught an exception while rendering: missing FROM-clause entry for table "vote" LINE 1: SELECT ((vote.karma_total - 1) / POW(2, 1.5)) AS "popularity... My index.html is simply: {% block content %} {% for link in links %} karma-up {{ link.karma_total }} karma-down {{ link.title }} Posted by {{ link.user }} to {{ link.category }} at {{ link.created }} {% empty %} No Links {% endfor %} {% endblock content %} EDIT 3 So very close! Again, all these answers are great but I am concentrating on a particular one because I feel it works best for my situation. from django.db.models import Sum from django.shortcuts import render_to_response from linkett.apps.links.models import * def index(request): popular_links = Link.objects.select_related().extra( select = { 'popularity': '(SUM(links_vote.karma_delta) - 1) / POW(2, 1.5)', }, tables = ['links_link', 'links_vote'], order_by = ['-popularity'], ) return render_to_response('links/test.html', {'links': popular_links}) Running this I am presented with an error hating on my lack of group by values. Specifically: TemplateSyntaxError at / Caught an exception while rendering: column "links_link.id" must appear in the GROUP BY clause or be used in an aggregate function LINE 1: ...karma_delta) - 1) / POW(2, 1.5)) AS "popularity", "links_lin... Not sure why my links_link.id wouldn't be in my group by but I am not sure how to alter my group by, django usually does that.

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  • Webby Nominations for Retail

    - by David Dorf
    The Webby Awards were created back in 1996 when the internet was just a baby. This is their 14th year of highlighting excellence on the Web, and there are lots of great nominations. Its quite amazing to see the rich content and interactivity of today's websites. Some interesting nominees for this year are: Sephora did a campaign at Christmas, and what remains of the Sephora Clause website is a bunch of wishes. The Starbucks "All you need is Love" campaign has lots of cool videos. The Sound Check from Walmart highlights raising music artists. Refinery29 has their fashion info hub. The five nominees in the retail category are: Bugaboo.com's website for selling high-end baby strollers. If you're looking for a high-end bag, check out Crumpler's flash-based e-commerce site. It's highly interactive, but a little on the slow side. I Make My Case sells custom designed iPod/iPhone and Blackberry cases. At MOO.com, they love to print. Tons of art for printing customized business cards, post cards, etc. If you want light shoes, check out Puma L.I.F.T. and see just how light shoes can weigh. Check them out, cast a few votes, and see if you're inspired to create something even better.

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  • SQL SERVER – Delay Command in SQL Server – SQL in Sixty Seconds #055

    - by Pinal Dave
    Have you ever needed WAIT or DELAY function in SQL Server?  Well, I personally have never needed it but I see lots of people asking for the same. It seems the need of the function is when developers are working with asynchronous applications or programs. When they are working with an application where user have to wait for a while for another application to complete the processing. If you are programming language developer, it is very easy for you to make the application wait for command however, in SQL I personally have rarely used this feature.  However, I have seen lots of developers asking for this feature in SQL Server, hence I have decided to build this quick video on the same subject. We can use WAITFOR DELAY ‘timepart‘ to create a SQL Statement to wait. Let us see the same concept in following SQL in Sixty Seconds Video: Related Tips in SQL in Sixty Seconds: Delay Function – WAITFOR clause – Delay Execution of Commands What would you like to see in the next SQL in Sixty Seconds video? Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Database, Pinal Dave, PostADay, SQL, SQL Authority, SQL in Sixty Seconds, SQL Interview Questions and Answers, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology, Video Tagged: Identity

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  • SQL SERVER – Find Most Expensive Queries Using DMV

    - by pinaldave
    The title of this post is what I can express here for this quick blog post. I was asked in recent query tuning consultation project, if I can share my script which I use to figure out which is the most expensive queries are running on SQL Server. This script is very basic and very simple, there are many different versions are available online. This basic script does do the job which I expect to do – find out the most expensive queries on SQL Server Box. SELECT TOP 10 SUBSTRING(qt.TEXT, (qs.statement_start_offset/2)+1, ((CASE qs.statement_end_offset WHEN -1 THEN DATALENGTH(qt.TEXT) ELSE qs.statement_end_offset END - qs.statement_start_offset)/2)+1), qs.execution_count, qs.total_logical_reads, qs.last_logical_reads, qs.total_logical_writes, qs.last_logical_writes, qs.total_worker_time, qs.last_worker_time, qs.total_elapsed_time/1000000 total_elapsed_time_in_S, qs.last_elapsed_time/1000000 last_elapsed_time_in_S, qs.last_execution_time, qp.query_plan FROM sys.dm_exec_query_stats qs CROSS APPLY sys.dm_exec_sql_text(qs.sql_handle) qt CROSS APPLY sys.dm_exec_query_plan(qs.plan_handle) qp ORDER BY qs.total_logical_reads DESC -- logical reads -- ORDER BY qs.total_logical_writes DESC -- logical writes -- ORDER BY qs.total_worker_time DESC -- CPU time You can change the ORDER BY clause to order this table with different parameters. I invite my reader to share their scripts. 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, SQLAuthority News, SQLServer, T SQL, Technology Tagged: SQL DMV

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  • SmartAssembly Support: How to change the maps folder

    - by Bart Read
    If you've set up SmartAssembly to store error reports in a SQL Server database, you'll also have specified a folder for the map files that are used to de-obfuscate error reports (see Figure 1). Whilst you can change the database easily enough you can't change the map folder path via the UI - if you click on it, it'll just open the folder in Explorer - but never fear, you can change it manually and fortunately it's not that difficult. (If you want to get to these settings click the Tools > Options link on the left-hand side of the SmartAssembly main window.)   Figure 1. Error reports database settings in SmartAssembly. The folder path is actually stored in the database, so you just need to open up SQL Server Management Studio, connect to the SQL Server where your error reports database is stored, then open a new query on the SmartAssembly database by right-clicking on it in the Object Explorer, then clicking New Query (see figure 2).     Figure 2. Opening a new query against the SmartAssembly error reports database in SQL Server. Now execute the following SQL query in the new query window: SELECT * FROM dbo.Information You should find that you get a result set rather like that shown in figure 3. You can see that the map folder path is stored in the MapFolderNetworkPath column.   Figure 3. Contents of the dbo.Information table, showing the map folder path I set in SmartAssembly. All I need to do to change this is execute the following SQL: UPDATE dbo.Information SET MapFolderNetworkPath = '\\UNCPATHTONEWFOLDER' WHERE MapFolderNetworkPath = '\\dev-ltbart\SAMaps' This will change the map folder path to whatever I supply in the SET clause. Once you've done this, you can verify the change by executing the following again: SELECT * FROM dbo.Information You should find the result set contains the new path you've set.

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  • SQL SERVER – Importing CSV File Into Database – SQL in Sixty Seconds #018 – Video

    - by pinaldave
    Importing data into database is one of the most important tasks. I often receive questions regarding what is the quickest way to insert CSV data or how to import CSV Data into SQL Server Table. Honestly the process is very simple and the script is even simpler. In today’s SQL in Sixty Seconds Video we will learn how quickly we can insert CSV data into SQL Server. The steps to import CSV are very simple. Create Table Use Bulk Insert to import the data Verify the data Done! Absolutely it is that simple. More on Importing CSV Data: SQL SERVER – Import CSV File Into SQL Server Using Bulk Insert – Load Comma Delimited File Into SQL Server SQL SERVER – Import CSV File into Database Table Using SSIS SQL SERVER – Create a Comma Delimited List Using SELECT Clause From Table Column SQL SERVER – Comma Separated Values (CSV) from Table Column SQL SERVER – Comma Separated Values (CSV) from Table Column – Part 2 I encourage you to submit your ideas for SQL in Sixty Seconds. We will try to accommodate as many as we can. If we like your idea we promise to share with you educational material. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Database, Pinal Dave, PostADay, SQL, SQL Authority, SQL in Sixty Seconds, SQL Query, SQL Scripts, SQL Server, SQL Server Management Studio, SQL Tips and Tricks, T SQL, Technology, Video

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  • Using a "white list" for extracting terms for Text Mining, Part 2

    - by [email protected]
    In my last post, we set the groundwork for extracting specific tokens from a white list using a CTXRULE index. In this post, we will populate a table with the extracted tokens and produce a case table suitable for clustering with Oracle Data Mining. Our corpus of documents will be stored in a database table that is defined as create table documents(id NUMBER, text VARCHAR2(4000)); However, any suitable Oracle Text-accepted data type can be used for the text. We then create a table to contain the extracted tokens. The id column contains the unique identifier (or case id) of the document. The token column contains the extracted token. Note that a given document many have many tokens, so there will be one row per token for a given document. create table extracted_tokens (id NUMBER, token VARCHAR2(4000)); The next step is to iterate over the documents and extract the matching tokens using the index and insert them into our token table. We use the MATCHES function for matching the query_string from my_thesaurus_rules with the text. DECLARE     cursor c2 is       select id, text       from documents; BEGIN     for r_c2 in c2 loop        insert into extracted_tokens          select r_c2.id id, main_term token          from my_thesaurus_rules          where matches(query_string,                        r_c2.text)>0;     end loop; END; Now that we have the tokens, we can compute the term frequency - inverse document frequency (TF-IDF) for each token of each document. create table extracted_tokens_tfidf as   with num_docs as (select count(distinct id) doc_cnt                     from extracted_tokens),        tf       as (select a.id, a.token,                            a.token_cnt/b.num_tokens token_freq                     from                        (select id, token, count(*) token_cnt                        from extracted_tokens                        group by id, token) a,                       (select id, count(*) num_tokens                        from extracted_tokens                        group by id) b                     where a.id=b.id),        doc_freq as (select token, count(*) overall_token_cnt                     from extracted_tokens                     group by token)   select tf.id, tf.token,          token_freq * ln(doc_cnt/df.overall_token_cnt) tf_idf   from num_docs,        tf,        doc_freq df   where df.token=tf.token; From the WITH clause, the num_docs query simply counts the number of documents in the corpus. The tf query computes the term (token) frequency by computing the number of times each token appears in a document and divides that by the number of tokens found in the document. The doc_req query counts the number of times the token appears overall in the corpus. In the SELECT clause, we compute the tf_idf. Next, we create the nested table required to produce one record per case, where a case corresponds to an individual document. Here, we COLLECT all the tokens for a given document into the nested column extracted_tokens_tfidf_1. CREATE TABLE extracted_tokens_tfidf_nt              NESTED TABLE extracted_tokens_tfidf_1                  STORE AS extracted_tokens_tfidf_tab AS              select id,                     cast(collect(DM_NESTED_NUMERICAL(token,tf_idf)) as DM_NESTED_NUMERICALS) extracted_tokens_tfidf_1              from extracted_tokens_tfidf              group by id;   To build the clustering model, we create a settings table and then insert the various settings. Most notable are the number of clusters (20), using cosine distance which is better for text, turning off auto data preparation since the values are ready for mining, the number of iterations (20) to get a better model, and the split criterion of size for clusters that are roughly balanced in number of cases assigned. CREATE TABLE km_settings (setting_name  VARCHAR2(30), setting_value VARCHAR2(30)); BEGIN  INSERT INTO km_settings (setting_name, setting_value) VALUES     VALUES (dbms_data_mining.clus_num_clusters, 20);  INSERT INTO km_settings (setting_name, setting_value)     VALUES (dbms_data_mining.kmns_distance, dbms_data_mining.kmns_cosine);   INSERT INTO km_settings (setting_name, setting_value) VALUES     VALUES (dbms_data_mining.prep_auto,dbms_data_mining.prep_auto_off);   INSERT INTO km_settings (setting_name, setting_value) VALUES     VALUES (dbms_data_mining.kmns_iterations,20);   INSERT INTO km_settings (setting_name, setting_value) VALUES     VALUES (dbms_data_mining.kmns_split_criterion,dbms_data_mining.kmns_size);   COMMIT; END; With this in place, we can now build the clustering model. BEGIN     DBMS_DATA_MINING.CREATE_MODEL(     model_name          => 'TEXT_CLUSTERING_MODEL',     mining_function     => dbms_data_mining.clustering,     data_table_name     => 'extracted_tokens_tfidf_nt',     case_id_column_name => 'id',     settings_table_name => 'km_settings'); END;To generate cluster names from this model, check out my earlier post on that topic.

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  • Exception Handling

    - by raghu.yadav
    Here is the few links on which andre had demonstrateddifferences-of-handling-jboexception-in handling-exceptions-in-oracle-ui-shell However in this post we can see how to display exception in popup being in the same page. I use similar usecase as andre however we'll not be using Exception Handling property from taskflow, instead we use popup and invoke the same programmatically. This is a dynamic region example where user can select jobs or locations links to edit the records of corresponding tables being in the same page and click commit to save changes. To generate exception we deliberately change commit to CommitAction in commit action binding code created in the bean (same as andre) and catch the exception and add brief description of exception into #{pageFlowScope.message}. Drop Popup component after Commit button and add dialog within in popup button, bind the popup component to backing bean and invoke the same in catch clause as shown below. public String Commit() { try{ BindingContainer bindings = getBindings(); OperationBinding operationBinding = bindings.getOperationBinding("CommitAction"); Object result = operationBinding.execute(); if (!operationBinding.getErrors().isEmpty()) { return null; } }catch (NullPointerException e) { setELValue("#{pageFlowScope.message}", "NullPointerException..."); e.printStackTrace(); String popupId = this.getPopup().getClientId(FacesContext.getCurrentInstance()); PatternsPublicUtil.invokePopup(popupId); } return null; } } private void setELValue(String el, String value) { FacesContext facesContext = FacesContext.getCurrentInstance(); ELContext elContext = facesContext.getELContext(); ExpressionFactory expressionFactory = facesContext.getApplication().getExpressionFactory(); ValueExpression valueExp = expressionFactory.createValueExpression(elContext, el, Object.class); valueExp.setValue(elContext, value); } .

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  • SQL SERVER – Puzzle to Win Print Book – Write T-SQL Self Join Without Using FIRST _VALUE and LAST_VALUE

    - by pinaldave
    Last week we asked a puzzle SQL SERVER – Puzzle to Win Print Book – Functions FIRST_VALUE and LAST_VALUE with OVER clause and ORDER BY . This puzzle got very interesting participation. The details of the winner is listed here. In this puzzle we received two very important feedback. This puzzle cleared the concepts of First_Value and Last_Value to the participants. As this was based on SQL Server 2012 many could not participate it as they have yet not installed SQL Server 2012. I really appreciate the feedback of user and decided to come up something as fun and helps learn new feature of SQL Server 2012. Please read yesterday’s blog post SQL SERVER – Introduction to LEAD and LAG – Analytic Functions Introduced in SQL Server 2012 before continuing this puzzle as it is based on yesterday’s post. Yesterday I ran following query which uses functions LEAD and LAG. USE AdventureWorks GO SELECT s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty, FIRST_VALUE(SalesOrderDetailID) OVER (ORDER BY SalesOrderDetailID) FstValue, LAST_VALUE(SalesOrderDetailID) OVER (ORDER BY SalesOrderDetailID) LstValue FROM Sales.SalesOrderDetail s WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY s.SalesOrderID,s.SalesOrderDetailID,s.OrderQty GO The above query will give us the following result: Puzzle: Now use T-SQL Self Join where same table is joined to itself and get the same result without using LEAD or LAG functions. Hint: Introduction to JOINs – Basic of JOINs Self Join A new analytic functions in SQL Server Denali CTP3 – LEAD() and LAG() Rules Leave a comment with your detailed answer by Nov 21's blog post. Open world-wide (where Amazon ships books) If you blog about puzzle’s solution and if you win, you win additional surprise gift as well. Prizes Print copy of my new book SQL Server Interview Questions Amazon|Flipkart If you already have this book, you can opt for any of my other books SQL Wait Stats [Amazon|Flipkart|Kindle] and SQL Programming [Amazon|Flipkart|Kindle]. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Function, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • So…is it a Seek or a Scan?

    - by Paul White
    You’re probably most familiar with the terms ‘Seek’ and ‘Scan’ from the graphical plans produced by SQL Server Management Studio (SSMS).  The image to the left shows the most common ones, with the three types of scan at the top, followed by four types of seek.  You might look to the SSMS tool-tip descriptions to explain the differences between them: Not hugely helpful are they?  Both mention scans and ranges (nothing about seeks) and the Index Seek description implies that it will not scan the index entirely (which isn’t necessarily true). Recall also yesterday’s post where we saw two Clustered Index Seek operations doing very different things.  The first Seek performed 63 single-row seeking operations; and the second performed a ‘Range Scan’ (more on those later in this post).  I hope you agree that those were two very different operations, and perhaps you are wondering why there aren’t different graphical plan icons for Range Scans and Seeks?  I have often wondered about that, and the first person to mention it after yesterday’s post was Erin Stellato (twitter | blog): Before we go on to make sense of all this, let’s look at another example of how SQL Server confusingly mixes the terms ‘Scan’ and ‘Seek’ in different contexts.  The diagram below shows a very simple heap table with two columns, one of which is the non-clustered Primary Key, and the other has a non-unique non-clustered index defined on it.  The right hand side of the diagram shows a simple query, it’s associated query plan, and a couple of extracts from the SSMS tool-tip and Properties windows. Notice the ‘scan direction’ entry in the Properties window snippet.  Is this a seek or a scan?  The different references to Scans and Seeks are even more pronounced in the XML plan output that the graphical plan is based on.  This fragment is what lies behind the single Index Seek icon shown above: You’ll find the same confusing references to Seeks and Scans throughout the product and its documentation. Making Sense of Seeks Let’s forget all about scans for a moment, and think purely about seeks.  Loosely speaking, a seek is the process of navigating an index B-tree to find a particular index record, most often at the leaf level.  A seek starts at the root and navigates down through the levels of the index to find the point of interest: Singleton Lookups The simplest sort of seek predicate performs this traversal to find (at most) a single record.  This is the case when we search for a single value using a unique index and an equality predicate.  It should be readily apparent that this type of search will either find one record, or none at all.  This operation is known as a singleton lookup.  Given the example table from before, the following query is an example of a singleton lookup seek: Sadly, there’s nothing in the graphical plan or XML output to show that this is a singleton lookup – you have to infer it from the fact that this is a single-value equality seek on a unique index.  The other common examples of a singleton lookup are bookmark lookups – both the RID and Key Lookup forms are singleton lookups (an RID lookup finds a single record in a heap from the unique row locator, and a Key Lookup does much the same thing on a clustered table).  If you happen to run your query with STATISTICS IO ON, you will notice that ‘Scan Count’ is always zero for a singleton lookup. Range Scans The other type of seek predicate is a ‘seek plus range scan’, which I will refer to simply as a range scan.  The seek operation makes an initial descent into the index structure to find the first leaf row that qualifies, and then performs a range scan (either backwards or forwards in the index) until it reaches the end of the scan range. The ability of a range scan to proceed in either direction comes about because index pages at the same level are connected by a doubly-linked list – each page has a pointer to the previous page (in logical key order) as well as a pointer to the following page.  The doubly-linked list is represented by the green and red dotted arrows in the index diagram presented earlier.  One subtle (but important) point is that the notion of a ‘forward’ or ‘backward’ scan applies to the logical key order defined when the index was built.  In the present case, the non-clustered primary key index was created as follows: CREATE TABLE dbo.Example ( key_col INTEGER NOT NULL, data INTEGER NOT NULL, CONSTRAINT [PK dbo.Example key_col] PRIMARY KEY NONCLUSTERED (key_col ASC) ) ; Notice that the primary key index specifies an ascending sort order for the single key column.  This means that a forward scan of the index will retrieve keys in ascending order, while a backward scan would retrieve keys in descending key order.  If the index had been created instead on key_col DESC, a forward scan would retrieve keys in descending order, and a backward scan would return keys in ascending order. A range scan seek predicate may have a Start condition, an End condition, or both.  Where one is missing, the scan starts (or ends) at one extreme end of the index, depending on the scan direction.  Some examples might help clarify that: the following diagram shows four queries, each of which performs a single seek against a column holding every integer from 1 to 100 inclusive.  The results from each query are shown in the blue columns, and relevant attributes from the Properties window appear on the right: Query 1 specifies that all key_col values less than 5 should be returned in ascending order.  The query plan achieves this by seeking to the start of the index leaf (there is no explicit starting value) and scanning forward until the End condition (key_col < 5) is no longer satisfied (SQL Server knows it can stop looking as soon as it finds a key_col value that isn’t less than 5 because all later index entries are guaranteed to sort higher). Query 2 asks for key_col values greater than 95, in descending order.  SQL Server returns these results by seeking to the end of the index, and scanning backwards (in descending key order) until it comes across a row that isn’t greater than 95.  Sharp-eyed readers may notice that the end-of-scan condition is shown as a Start range value.  This is a bug in the XML show plan which bubbles up to the Properties window – when a backward scan is performed, the roles of the Start and End values are reversed, but the plan does not reflect that.  Oh well. Query 3 looks for key_col values that are greater than or equal to 10, and less than 15, in ascending order.  This time, SQL Server seeks to the first index record that matches the Start condition (key_col >= 10) and then scans forward through the leaf pages until the End condition (key_col < 15) is no longer met. Query 4 performs much the same sort of operation as Query 3, but requests the output in descending order.  Again, we have to mentally reverse the Start and End conditions because of the bug, but otherwise the process is the same as always: SQL Server finds the highest-sorting record that meets the condition ‘key_col < 25’ and scans backward until ‘key_col >= 20’ is no longer true. One final point to note: seek operations always have the Ordered: True attribute.  This means that the operator always produces rows in a sorted order, either ascending or descending depending on how the index was defined, and whether the scan part of the operation is forward or backward.  You cannot rely on this sort order in your queries of course (you must always specify an ORDER BY clause if order is important) but SQL Server can make use of the sort order internally.  In the four queries above, the query optimizer was able to avoid an explicit Sort operator to honour the ORDER BY clause, for example. Multiple Seek Predicates As we saw yesterday, a single index seek plan operator can contain one or more seek predicates.  These seek predicates can either be all singleton seeks or all range scans – SQL Server does not mix them.  For example, you might expect the following query to contain two seek predicates, a singleton seek to find the single record in the unique index where key_col = 10, and a range scan to find the key_col values between 15 and 20: SELECT key_col FROM dbo.Example WHERE key_col = 10 OR key_col BETWEEN 15 AND 20 ORDER BY key_col ASC ; In fact, SQL Server transforms the singleton seek (key_col = 10) to the equivalent range scan, Start:[key_col >= 10], End:[key_col <= 10].  This allows both range scans to be evaluated by a single seek operator.  To be clear, this query results in two range scans: one from 10 to 10, and one from 15 to 20. Final Thoughts That’s it for today – tomorrow we’ll look at monitoring singleton lookups and range scans, and I’ll show you a seek on a heap table. Yes, a seek.  On a heap.  Not an index! If you would like to run the queries in this post for yourself, there’s a script below.  Thanks for reading! IF OBJECT_ID(N'dbo.Example', N'U') IS NOT NULL BEGIN DROP TABLE dbo.Example; END ; -- Test table is a heap -- Non-clustered primary key on 'key_col' CREATE TABLE dbo.Example ( key_col INTEGER NOT NULL, data INTEGER NOT NULL, CONSTRAINT [PK dbo.Example key_col] PRIMARY KEY NONCLUSTERED (key_col) ) ; -- Non-unique non-clustered index on the 'data' column CREATE NONCLUSTERED INDEX [IX dbo.Example data] ON dbo.Example (data) ; -- Add 100 rows INSERT dbo.Example WITH (TABLOCKX) ( key_col, data ) SELECT key_col = V.number, data = V.number FROM master.dbo.spt_values AS V WHERE V.[type] = N'P' AND V.number BETWEEN 1 AND 100 ; -- ================ -- Singleton lookup -- ================ ; -- Single value equality seek in a unique index -- Scan count = 0 when STATISTIS IO is ON -- Check the XML SHOWPLAN SELECT E.key_col FROM dbo.Example AS E WHERE E.key_col = 32 ; -- =========== -- Range Scans -- =========== ; -- Query 1 SELECT E.key_col FROM dbo.Example AS E WHERE E.key_col <= 5 ORDER BY E.key_col ASC ; -- Query 2 SELECT E.key_col FROM dbo.Example AS E WHERE E.key_col > 95 ORDER BY E.key_col DESC ; -- Query 3 SELECT E.key_col FROM dbo.Example AS E WHERE E.key_col >= 10 AND E.key_col < 15 ORDER BY E.key_col ASC ; -- Query 4 SELECT E.key_col FROM dbo.Example AS E WHERE E.key_col >= 20 AND E.key_col < 25 ORDER BY E.key_col DESC ; -- Final query (singleton + range = 2 range scans) SELECT E.key_col FROM dbo.Example AS E WHERE E.key_col = 10 OR E.key_col BETWEEN 15 AND 20 ORDER BY E.key_col ASC ; -- === TIDY UP === DROP TABLE dbo.Example; © 2011 Paul White email: [email protected] twitter: @SQL_Kiwi

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  • SQL SERVER – Introduction to PERCENTILE_CONT() – Analytic Functions Introduced in SQL Server 2012

    - by pinaldave
    SQL Server 2012 introduces new analytical function PERCENTILE_CONT(). The book online gives following definition of this function: Computes a specific percentile for sorted values in an entire rowset or within distinct partitions of a rowset in Microsoft SQL Server 2012 Release Candidate 0 (RC 0). For a given percentile value P, PERCENTILE_DISC sorts the values of the expression in the ORDER BY clause and returns the value with the smallest CUME_DIST value (with respect to the same sort specification) that is greater than or equal to P. If you are clear with understanding of the function – no need to read further. If you got lost here is the same in simple words – it is lot like finding median with percentile value. Now let’s have fun following query: USE AdventureWorks GO SELECT SalesOrderID, OrderQty, ProductID, PERCENTILE_CONT(0.5) WITHIN GROUP (ORDER BY ProductID) OVER (PARTITION BY SalesOrderID) AS MedianCont FROM Sales.SalesOrderDetail WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY SalesOrderID DESC GO The above query will give us the following result: You can see that I have used PERCENTILE_COUNT(0.5) in query, which is similar to finding median. Let me explain above diagram with little more explanation. The defination of median is as following: In case of Even Number of elements = In ordered list add the two digits from the middle and devide by 2 In case of Odd Numbers of elements = In ordered list select the digits from the middle I hope this example gives clear idea how PERCENTILE_CONT() works. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Function, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • Using Take and skip keyword to filter records in LINQ

    - by vik20000in
    In LINQ we can use the take keyword to filter out the number of records that we want to retrieve from the query. Let’s say we want to retrieve only the first 5 records for the list or array then we can use the following query     int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };     var first3Numbers = numbers.Take(3); The TAKE keyword can also be easily applied to list of object in the following way. var first3WAOrders = (         from cust in customers         from order in cust.Orders         select cust ) .Take(3); [Note in the query above we are using the order clause so that the data is first ordered based on the orders field and then the first 3 records are taken. In both the above example we have been able to filter out data based on the number of records we want to fetch. But in both the cases we were fetching the records from the very beginning. But there can be some requirements whereby we want to fetch the records after skipping some of the records like in paging. For this purpose LINQ has provided us with the skip method which skips the number of records passed as parameter in the result set. int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 }; var allButFirst4Numbers = numbers.Skip(4); The SKIP keyword can also be easily applied to list of object in the following way. var first3WAOrders = (         from cust in customers         from order in cust.Orders         select cust ).Skip(3);  Vikram

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  • SQL SERVER – Copy Statistics from One Server to Another Server

    - by pinaldave
    I was recently working on a performance tuning project in Dubai (yeah I was able to see the tallest tower from the window of my work place). I had a very interesting learning experience there. There was a situation where we wanted to receive the schema of original database from a certain client. However, the client was not able to provide us any data due to privacy issues. The schema was very important because without having an access to underlying data, it was a bit difficult to judge the queries etc. For example, without any primary data, all the queries are running in 0 (zero) milliseconds and all were using nested loop as there were no data to be returned. Even though we had CPU offending queries, they were not doing anything without the data in the tables. This was really a challenge as I did not have access to production server data and I could not recreate the scenarios as production without data. Well, I was confused but Ruben from Solid Quality Mentors, Spain taught me new tricks. He suggested that when table schema is generated, we can create the statistics consequently. Here is how we had done that: Once statistics is created along with the schema, without data in the table, all the queries will work as how they will work on production server. This way, without access to the data, we were able to recreate the same scenario as production server on development server. When observed at the script, you will find that the statistics were also generated along with the query. You will find statistics included in WITH STATS_STREAM clause. What a very simple and effective script. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQLServer, T SQL, Technology Tagged: SQL Statistics, Statistics

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  • SQL SERVER – 2012 – Summary of All the Analytic Functions – MSDN and SQLAuthority

    - by pinaldave
    SQL Server 2012 (RC0 Available here) has introduced new analytic functions. These functions were long awaited and I am glad that they are here. Previously when any of this function was needed people use to write long T-SQL code to simulate that and now no need of the same. Having available native function also helps performance as well readability. In last few days I have written many articles on this subject on my blog. The goal was make these complex analytic functions easy to understand and make it widely accepted. As this new functions are available and as awareness spreads we should start using the new functions. Here is the quick list of the new function and relevant MSDN site. Function SQLAuthority MSDN CUME_DIST CUME_DIST CUME_DIST FIRST_VALUE FIRST_VALUE FIRST_VALUE LAST_VALUE LAST_VALUE LAST_VALUE LEAD LEAD LEAD LAG LAG LAG PERCENTILE_CONT PERCENTILE_CONT PERCENTILE_CONT PERCENTILE_DISC PERCENTILE_DISC PERCENTILE_DISC PERCENT_RANK PERCENT_RANK PERCENT_RANK I also enjoyed three different puzzles during the course of this series which gave clear idea to the SQL Server 2012 analytic functions. SQL SERVER – Puzzle to Win Print Book – Functions FIRST_VALUE and LAST_VALUE with OVER clause and ORDER BY SQL SERVER – Puzzle to Win Print Book – Write T-SQL Self Join Without Using LEAD and LAG SQL SERVER – Puzzle to Win Print Book – Explain Value of PERCENTILE_CONT() Using Simple Example This series will be always my dear series as during this series I had went through very unique experience of my book going out of stock and becoming available after 48 hours. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Function, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • TakeWhile and SkipWhile method in LINQ

    - by vik20000in
     In my last post I talked about how to use the take and the Skip keyword to filter out the number of records that we are fetching. But there is only problem with the take and skip statement. The problem lies in the dependency where by the number of records to be fetched has to be passed to it. Many a times the number of records to be fetched is also based on the query itself. For example if we want to continue fetching records till a certain condition is met on the record set. Let’s say we want to fetch records from the array of number till we get 7. For this kind of query LINQ has exposed the TakeWhile Method.     int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };     var firstNumbersLessThan6 = numbers.TakeWhile(n => n < 7);   In the same way we can also use the SkipWhile statement. The skip while statement will skip all the records that do not match certain condition provided. In the example below we are skiping all those number which are not divisible by 3. Remember we could have done this with where clause also, but SkipWhile method can be useful in many other situation and hence the example and the keyword.     int[] numbers = { 5, 4, 1, 3, 9, 8, 6, 7, 2, 0 };     var allButFirst3Numbers = numbers.SkipWhile(n => n % 3 != 0); Vikram

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  • SQL SERVER – Weekly Series – Memory Lane – #003

    - by pinaldave
    Here is the list of curetted articles of SQLAuthority.com across all these years. Instead of just listing all the articles I have selected a few of my most favorite articles and have listed them here with additional notes below it. Let me know which one of the following is your favorite article from memory lane. 2006 This was the first year of my blogging and lots of new things I was learning as I go. I was indeed an infant in blogging a few years ago. However, as time passed by I have learned a lot. This year was year of experiments and new learning. 2007 Working as a full time DBA I often encoutered various errors and I started to learn how to avoid those error and document the same. ERROR Msg 5174 Each file size must be greater than or equal to 512 KB Whenever I see this error I wonder why someone is trying to attempt a database which is extremely small. Anyway, it does not matter what I think I keep on seeing this error often in industries. Anyway the solution of the error is equally interesting – just created larger database. Dilbert Humor This was very first encounter with database humor and I started to love it. It does not matter how many time we read this cartoon it does not get old. Generate Script with Data from Database – Database Publishing Wizard Generating schema script with data is one of the most frequently performed tasks among SQL Server Data Professionals. There are many ways to do the same. In the above article I demonstrated that how we can use the Database Publishing Wizard to accomplish the same. It was new to me at that time but I have not seen much of the adoption of the same still in the industry. Here is one of my videos where I demonstrate how we can generate data with schema. 2008 Delete Backup History – Cleanup Backup History Deleting backup history is important too but should be done carefully. If this is not carried out at regular interval there is good chance that MSDB will be filled up with all the old history. Every organization is different. Some would like to keep the history for 30 days and some for a year but there should be some limit. One should regularly archive the database backup history. South Asia MVP Open Days 2008 This was my very first year Microsoft MVP. I had Indeed big blast at the event and the fun was incredible. After this event I have attended many different MVP events but the fun and learning this particular event presented was amazing and just like me many others are not able to forget the same. Here are other links related to the event: South Asia MVP Open Day 2008 – Goa South Asia MVP Open Day 2008 – Goa – Day 1 South Asia MVP Open Day 2008 – Goa – Day 2 South Asia MVP Open Day 2008 – Goa – Day 3 2009 Enable or Disable Constraint  This is very simple script but I personally keep on forgetting it so I had blogged it. Till today, I keep on referencing this again and again as sometime a very little thing is hard to remember. Policy Based Management – Create, Evaluate and Fix Policies This article will cover the most spectacular feature of SQL 2008 – Policy-based management and how the configuration of SQL Server with policy-based management architecture can make a powerful difference. Policy based management is loaded with several advantages. It can help you implement various policies for reliable configuration of the system. It also provides additional administrative assistance to DBAs and helps them effortlessly manage various tasks of SQL Server across the enterprise. SQLPASS 2009 – My Very First SQPASS Experience Just Brilliant! I never had an experience such a thing in my life. SQL SQL and SQL – all around SQL! I am listing my own reasons here in order of importance to me. Networking with SQL fellows and experts Putting face to the name or avatar Learning and improving my SQL skills Understanding the structure of the largest SQL Server Professional Association Attending my favorite training sessions Since last time I have never missed a single time this event. This event is my favorite event and something keeps me going. Here are additional post related SQLPASS 2009. SQL PASS Summit, Seattle 2009 – Day 1 SQL PASS Summit, Seattle 2009 – Day 2 SQL PASS Summit, Seattle 2009 – Day 3 SQL PASS Summit, Seattle 2009 – Day 4 2010 Get All the Information of Database using sys.databases Even though we believe that we know everything about our database, we do not know a lot of things about our database. This little script enables us to know so many details about databases which we may not be familiar with. Run this on your server today and see how much you know your database. Reducing CXPACKET Wait Stats for High Transactional Database While engaging in a performance tuning consultation for a client, a situation occurred where they were facing a lot of CXPACKET Waits Stats. The client asked me if I could help them reduce this huge number of wait stats. I usually receive this kind of request from other client as well, but the important thing to understand is whether this question has any merits or benefits, or not. I discusses the same in this article – a bit long but insightful for sure. Error related to Database in Use There are so many database management operations in SQL Server which requires exclusive access to the database and it is not always possible to get it. When any database is online in SQL Server it either applications or system thread often accesses them. This means database can’t have exclusive access and the operations which required this access throws an error. There is very easy method to overcome this minor issue – a single line script can give you exclusive access to the database. Difference between DATETIME and DATETIME2 Developers have found the root reason of the problem when dealing with Date Functions – when data time values are converted (implicit or explicit) between different data types, which would lose some precision, so the result cannot match each other as expected. In this blog post I go over very interesting details and difference between DATETIME and DATETIME2 History of SQL Server Database Encryption I recently met Michael Coles and Rodeney Landrum the author of one of the kind book Expert SQL Server 2008 Encryption at SQLPASS in Seattle. During the conversation we ended up how Microsoft is evolving encryption technology. The same discussion lead to talking about history of encryption tools in SQL Server. Michale pointed me to page 18 of his book of encryption. He explicitly gave me permission to re-produce relevant part of history from his book. 2011 Functions FIRST_VALUE and LAST_VALUE with OVER clause and ORDER BY Some time an interesting feature and smart audience make a total difference in places. From last two days, I have been writing on SQL Server 2012 feature FIRST_VALUE and LAST_VALUE. I created a puzzle which was very interesting and got many people attempt to resolve it. It was based on following two articles: Introduction to FIRST_VALUE and LAST_VALUE Introduction to FIRST_VALUE and LAST_VALUE with OVER clause I even provided the hint about how one can solve this problem. The best part was many people solved the problem without using hints! Try your luck!  A Real Story of Book Getting ‘Out of Stock’ to A 25% Discount Story Available This is a great problem and everybody would love to have it. We had it and we loved it. Our book got out of stock in 48 hours of releasing and stocks were empty. We faced many issues and learned many valuable lessons. Some we were able to avoid in the future and some we are still facing it as those problems have no solutions. However, since that day – our books never gone out of stock. This inspiring learning story for us and I am confident that you will love to read it as well. Introduction to LEAD and LAG – Analytic Functions Introduced in SQL Server 2012 SQL Server 2012 introduces new analytical function LEAD() and LAG(). This function accesses data from a subsequent row (for lead) and previous row (for lag) in the same result set without the use of a self-join . It will be very difficult to explain this in words so I will attempt small example to explain you this function. I had a fantastic time writing this blog post and I am very confident when you read it, you will like the same. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Memory Lane, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • OpenSource License Validation [closed]

    - by Macmade
    I'm basically looking for some kind of FLOSS/OpenSource license validation service. I have special needs for some projects I'd like to open-source. I know there's actually tons of different FLOSS/OpenSource licenses, each one suitable for some specific purpose, and that creating a «new» one is not something recommended, usually. Anyway, even if I'm not an expert in the legal domain, I've got some experience with FLOSS/OpenSource, at a legal level, and it seems there's just no license covering my needs. I actually wrote the license terms I'd like to use, and contacted the FSF, asking them to review that license, as it seems (at least that's written on their website) they can do such review work. No answer. I tried repetitively, but no luck. So I'm currently looking for an alternate legal expertise about that specific license. I don't mind paying such a service, as long as I can be sure the license can be recognised as a FLOSS/OpenSource license. About the license, it's basically a mix of a BSD (third-clause) with a BOOST software license. The difference is about redistribution. Source code redistribution shall retain the copyright novices. The same applies for binary redistribution (like BSD), unless it's distributed as a library (more like BOOST). I hope this question is OK for programmers.stackexchange. I'm usually more active on StackOverflow, but it just seems the right place for such a question. So thank you for your time and enlightened advices. : )

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  • My experience working with Teradata SQL Assistant

    - by Kevin Shyr
    Originally posted on: http://geekswithblogs.net/LifeLongTechie/archive/2014/05/28/my-experience-working-with-teradata-sql-assistant.aspx To this date, I still haven't figure out how to "toggle" between my query windows. It seems like unless I click on that "new" button on top, whatever SQL I generate from right-click just overrides the current SQL in the window. I'm probably missing a "generate new sql in new window" setting The default Teradata SQL Assistant doesn't execute just the SQL query I highlighted. There is a setting I have to change first. I'm not really happy that the SQL assistant and SQL admin are different app. Still trying to get used to the fact that I can't quickly look up a table's keys/relationships while writing query. I have to switch between windows. LOVE the execution plan / explanation. I think that part is better done than MS SQL in some ways. The error messages can be better. I feel that Teradata .NET provider sends smaller query command over than others. I don't have any hard data to support my claim. One of my query in SSRS was passing multi-valued parameters to another query, and got error "Teradata 3577 row size or sort key size overflow". The search on this error says the solution is to cast result column into smaller data type, but I found that the problem was that the parameter passed into the where clause could not be too large. I wish Teradata SQL Assistant would remember the window size I just adjusted to. Every time I execute the query, the result set, query, and exec log auto re-adjust back to the default size. In SSMS, if I adjust the result set area to be smaller, it would stay like that if I execute query in the same window.

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  • Top 5 Developer Enabling Nuggets in MySQL 5.6

    - by Rob Young
    MySQL 5.6 is truly a better MySQL and reflects Oracle's commitment to the evolution of the most popular and widelyused open source database on the planet.  The feature-complete 5.6 release candidate was announced at MySQL Connect in late September and the production-ready, generally available ("GA") product should be available in early 2013.  While the message around 5.6 has been focused mainly on mass appeal, advanced topics like performance/scale, high availability, and self-healing replication clusters, MySQL 5.6 also provides many developer-friendly nuggets that are designed to enable those who are building the next generation of web-based and embedded applications and services. Boiling down the 5.6 feature set into a smaller set, of simple, easy to use goodies designed with developer agility in mind, these things deserve a quick look:Subquery Optimizations Using semi-JOINs and late materialization, the MySQL 5.6 Optimizer delivers greatly improved subquery performance. Specifically, the optimizer is now more efficient in handling subqueries in the FROM clause; materialization of subqueries in the FROM clause is now postponed until their contents are needed during execution. Additionally, the optimizer may add an index to derived tables during execution to speed up row retrieval. Internal tests run using the DBT-3 benchmark Query #13, shown below, demonstrate an order of magnitude improvement in execution times (from days to seconds) over previous versions. select c_name, c_custkey, o_orderkey, o_orderdate, o_totalprice, sum(l_quantity)from customer, orders, lineitemwhere o_orderkey in (                select l_orderkey                from lineitem                group by l_orderkey                having sum(l_quantity) > 313  )  and c_custkey = o_custkey  and o_orderkey = l_orderkeygroup by c_name, c_custkey, o_orderkey, o_orderdate, o_totalpriceorder by o_totalprice desc, o_orderdateLIMIT 100;What does this mean for developers?  For starters, simplified subqueries can now be coded instead of complex joins for cross table lookups: SELECT title FROM film WHERE film_id IN (SELECT film_id FROM film_actor GROUP BY film_id HAVING count(*) > 12); And even more importantly subqueries embedded in packaged applications no longer need to be re-written into joins.  This is good news for both ISVs and their customers who have access to the underlying queries and who have spent development cycles writing, testing and maintaining their own versions of re-written queries across updated versions of a packaged app.The details are in the MySQL 5.6 docs. Online DDL OperationsToday's web-based applications are designed to rapidly evolve and adapt to meet business and revenue-generationrequirements. As a result, development SLAs are now most often measured in minutes vs days or weeks. For example, when an application must quickly support new product lines or new products within existing product lines, the backend database schema must adapt in kind, and most commonly while the application remains available for normal business operations.  MySQL 5.6 supports this level of online schema flexibility and agility by providing the following new ALTER TABLE online DDL syntax additions:  CREATE INDEX DROP INDEX Change AUTO_INCREMENT value for a column ADD/DROP FOREIGN KEY Rename COLUMN Change ROW FORMAT, KEY_BLOCK_SIZE for a table Change COLUMN NULL, NOT_NULL Add, drop, reorder COLUMN Again, the details are in the MySQL 5.6 docs. Key-value access to InnoDB via Memcached APIMany of the next generation of web, cloud, social and mobile applications require fast operations against simple Key/Value pairs. At the same time, they must retain the ability to run complex queries against the same data, as well as ensure the data is protected with ACID guarantees. With the new NoSQL API for InnoDB, developers have allthe benefits of a transactional RDBMS, coupled with the performance capabilities of Key/Value store.MySQL 5.6 provides simple, key-value interaction with InnoDB data via the familiar Memcached API.  Implemented via a new Memcached daemon plug-in to mysqld, the new Memcached protocol is mapped directly to the native InnoDB API and enables developers to use existing Memcached clients to bypass the expense of query parsing and go directly to InnoDB data for lookups and transactional compliant updates.  The API makes it possible to re-use standard Memcached libraries and clients, while extending Memcached functionality by integrating a persistent, crash-safe, transactional database back-end.  The implementation is shown here:So does this option provide a performance benefit over SQL?  Internal performance benchmarks using a customized Java application and test harness show some very promising results with a 9X improvement in overall throughput for SET/INSERT operations:You can follow the InnoDB team blog for the methodology, implementation and internal test cases that generated these results here. How to get started with Memcached API to InnoDB is here. New Instrumentation in Performance SchemaThe MySQL Performance Schema was introduced in MySQL 5.5 and is designed to provide point in time metrics for key performance indicators.  MySQL 5.6 improves the Performance Schema in answer to the most common DBA and Developer problems.  New instrumentations include: Statements/Stages What are my most resource intensive queries? Where do they spend time? Table/Index I/O, Table Locks Which application tables/indexes cause the most load or contention? Users/Hosts/Accounts Which application users, hosts, accounts are consuming the most resources? Network I/O What is the network load like? How long do sessions idle? Summaries Aggregated statistics grouped by statement, thread, user, host, account or object. The MySQL 5.6 Performance Schema is now enabled by default in the my.cnf file with optimized and auto-tune settings that minimize overhead (< 5%, but mileage will vary), so using the Performance Schema ona production server to monitor the most common application use cases is less of an issue.  In addition, new atomic levels of instrumentation enable the capture of granular levels of resource consumption by users, hosts, accounts, applications, etc. for billing and chargeback purposes in cloud computing environments.The MySQL docs are an excellent resource for all that is available and that can be done with the 5.6 Performance Schema. Better Condition Handling - GET DIAGNOSTICSMySQL 5.6 enables developers to easily check for error conditions and code for exceptions by introducing the new MySQL Diagnostics Area and corresponding GET DIAGNOSTICS interface command. The Diagnostic Area can be populated via multiple options and provides 2 kinds of information:Statement - which provides affected row count and number of conditions that occurredCondition - which provides error codes and messages for all conditions that were returned by a previous operation The addressable items for each are: The new GET DIAGNOSTICS command provides a standard interface into the Diagnostics Area and can be used via the CLI or from within application code to easily retrieve and handle the results of the most recent statement execution.  An example of how it is used might be:mysql> DROP TABLE test.no_such_table; ERROR 1051 (42S02): Unknown table 'test.no_such_table' mysql> GET DIAGNOSTICS CONDITION 1 -> @p1 = RETURNED_SQLSTATE, @p2 = MESSAGE_TEXT; mysql> SELECT @p1, @p2; +-------+------------------------------------+| @p1   | @p2                                | +-------+------------------------------------+| 42S02 | Unknown table 'test.no_such_table' | +-------+------------------------------------+ Options for leveraging the MySQL Diagnotics Area and GET DIAGNOSTICS are detailed in the MySQL Docs.While the above is a summary of some of the key developer enabling 5.6 features, it is by no means exhaustive. You can dig deeper into what MySQL 5.6 has to offer by reading this developer zone article or checking out "What's New in MySQL 5.6" in the MySQL docs.BONUS ALERT!  If you are developing on Windows or are considering MySQL as an alternative to SQL Server for your next project, application or shipping product, you should check out the MySQL Installer for Windows.  The installer includes the MySQL 5.6 RC database, all drivers, Visual Studio and Excel plugins, tray monitor and development tools all a single download and GUI installer.   So what are your next steps? Register for Dec. 13 "MySQL 5.6: Building the Next Generation of Web-Based Applications and Services" live web event.  Hurry!  Seats are limited. Download the MySQL 5.6 Release Candidate (look under the Development Releases tab) Provide Feedback <link to http://bugs.mysql.com/> Join the Developer discussion on the MySQL Forums Explore all MySQL Products and Developer Tools As always, thanks for your continued support of MySQL!

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