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  • SQL SERVER Subquery or Join Various Options SQL Server Engine knows the Best

    This is followup post of my earlier article SQL SERVER Convert IN to EXISTS Performance Talk, after reading all the comments I have received I felt that I could write more on the same subject to clear few things out. First let us run following four queries, all of them are giving exactly [...]...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • SEO - The Right Tools For You

    Research has proved that usually a lot of people only visit the page that the search engine has on the top. If you are tired of not getting traffic on your site and want your page to be the first one the search engine optimizes, you can take help of the SEO tools.

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  • Screen has 1px vertical dead area on the right side

    - by pileofrocks
    Meaning that I can not click anything on that 1px vertical area (such as scrollbars). Illustration (purple = screen, black = the dead area): I am thinking Compiz has to be the main suspect, especially as on a guest account, this problem does not exist. I have a dual-monitor setup and this does not happen on the 2nd screen. However, turning off the 2nd display does not make any difference. I had this issue already before upgrading to 13.10 and while doing that, I also resetted all Compiz settings and re-loaded my profile configuration file. I have tried disabling all Compiz plugins under "Window Management" What next?

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  • Right-size IT Budgets with Windows Server 2012 "Storage Spaces"

    - by KeithMayer
    What is the Largest Single Cost Category in Your IT Hardware Budget? If you're like most of the enterprise customer organizations that were surveyed when we were designing Windows Server 2012, your answer is probably the same as theirs: STORAGE! For the organizations we surveyed, we found that as much as 60% of their annual hardware budgets were allocated to expensive hardware SAN solutions due to ever-increasing storage requirements. Wouldn't it be nice to have some of that budget back

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  • Database Maintenance Scripting Done Right

    - by KKline
    I first wrote about useful database maintenance scripts on my SQLBlog account way back in 2008. Hmmm - now that I think about it, I first wrote about my own useful database maintenance scripts in a journal called SQL Server Professional back in the mid-1990's on SQL Server v6.5 or some such. But I digress... Anyway, I pointed out a couple useful sites where you could get some good scripts that would take care of preventative maintenance on your SQL Server, such as index defragmentation, updating...(read more)

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  • Finding bugs is difficult, right?

    - by Laila
    Something I hear developers tell us all the time is that they take pride in being a developer.and that bugs are a dent in that pride. Someone once told me "I know I have found bugs years later, and it's the worst feeling in the world." So how can you avoid that sinking feeling when you find out a bug has been in production months before someone lets you know about it? Besides, let's face it: hearing about a bug often means a world of pain, because it can take hours to track down where the problem is and more hours (if not days) to fix it. And during that time, you're not working on something new, and that, my friends, is really frustrating! So to cheer you up, we've created a Bug Hunt game, where you battle against the clock to spot bugs. We've really enjoyed putting this together and hope you enjoy playing it too. Once you're done with the bug hunt, we explain how easy it can be to find and fix bugs in real life, using a neat mechanism that we call Automated Error Reporting. Play the game now.

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  • Secure Your Wireless Router: 8 Things You Can Do Right Now

    - by Chris Hoffman
    A security researcher recently discovered a backdoor in many D-Link routers, allowing anyone to access the router without knowing the username or password. This isn’t the first router security issue and won’t be the last. To protect yourself, you should ensure that your router is configured securely. This is about more than just enabling Wi-Fi encryption and not hosting an open Wi-Fi network. Disable Remote Access Routers offer a web interface, allowing you to configure them through a browser. The router runs a web server and makes this web page available when you’re on the router’s local network. However, most routers offer a “remote access” feature that allows you to access this web interface from anywhere in the world. Even if you set a username and password, if you have a D-Link router affected by this vulnerability, anyone would be able to log in without any credentials. If you have remote access disabled, you’d be safe from people remotely accessing your router and tampering with it. To do this, open your router’s web interface and look for the “Remote Access,” “Remote Administration,” or “Remote Management” feature. Ensure it’s disabled — it should be disabled by default on most routers, but it’s good to check. Update the Firmware Like our operating systems, web browsers, and every other piece of software we use, router software isn’t perfect. The router’s firmware — essentially the software running on the router — may have security flaws. Router manufacturers may release firmware updates that fix such security holes, although they quickly discontinue support for most routers and move on to the next models. Unfortunately, most routers don’t have an auto-update feature like Windows and our web browsers do — you have to check your router manufacturer’s website for a firmware update and install it manually via the router’s web interface. Check to be sure your router has the latest available firmware installed. Change Default Login Credentials Many routers have default login credentials that are fairly obvious, such as the password “admin”. If someone gained access to your router’s web interface through some sort of vulnerability or just by logging onto your Wi-Fi network, it would be easy to log in and tamper with the router’s settings. To avoid this, change the router’s password to a non-default password that an attacker couldn’t easily guess. Some routers even allow you to change the username you use to log into your router. Lock Down Wi-Fi Access If someone gains access to your Wi-Fi network, they could attempt to tamper with your router — or just do other bad things like snoop on your local file shares or use your connection to downloaded copyrighted content and get you in trouble. Running an open Wi-Fi network can be dangerous. To prevent this, ensure your router’s Wi-Fi is secure. This is pretty simple: Set it to use WPA2 encryption and use a reasonably secure passphrase. Don’t use the weaker WEP encryption or set an obvious passphrase like “password”. Disable UPnP A variety of UPnP flaws have been found in consumer routers. Tens of millions of consumer routers respond to UPnP requests from the Internet, allowing attackers on the Internet to remotely configure your router. Flash applets in your browser could use UPnP to open ports, making your computer more vulnerable. UPnP is fairly insecure for a variety of reasons. To avoid UPnP-based problems, disable UPnP on your router via its web interface. If you use software that needs ports forwarded — such as a BitTorrent client, game server, or communications program — you’ll have to forward ports on your router without relying on UPnP. Log Out of the Router’s Web Interface When You’re Done Configuring It Cross site scripting (XSS) flaws have been found in some routers. A router with such an XSS flaw could be controlled by a malicious web page, allowing the web page to configure settings while you’re logged in. If your router is using its default username and password, it would be easy for the malicious web page to gain access. Even if you changed your router’s password, it would be theoretically possible for a website to use your logged-in session to access your router and modify its settings. To prevent this, just log out of your router when you’re done configuring it — if you can’t do that, you may want to clear your browser cookies. This isn’t something to be too paranoid about, but logging out of your router when you’re done using it is a quick and easy thing to do. Change the Router’s Local IP Address If you’re really paranoid, you may be able to change your router’s local IP address. For example, if its default address is 192.168.0.1, you could change it to 192.168.0.150. If the router itself were vulnerable and some sort of malicious script in your web browser attempted to exploit a cross site scripting vulnerability, accessing known-vulnerable routers at their local IP address and tampering with them, the attack would fail. This step isn’t completely necessary, especially since it wouldn’t protect against local attackers — if someone were on your network or software was running on your PC, they’d be able to determine your router’s IP address and connect to it. Install Third-Party Firmwares If you’re really worried about security, you could also install a third-party firmware such as DD-WRT or OpenWRT. You won’t find obscure back doors added by the router’s manufacturer in these alternative firmwares. Consumer routers are shaping up to be a perfect storm of security problems — they’re not automatically updated with new security patches, they’re connected directly to the Internet, manufacturers quickly stop supporting them, and many consumer routers seem to be full of bad code that leads to UPnP exploits and easy-to-exploit backdoors. It’s smart to take some basic precautions. Image Credit: Nuscreen on Flickr     

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  • Right tool for the job(html5 vs silverlight)

    - by Jargo
    I have been tasked to develop a web based offer request application for bathrooms and I am asking opinions on which tool should I choose. I have narrowed options down to two (html5 and silverlight). Most of the application consists of basic UI elements that could be achieved with html4. However most challenging part is the design view for the bathroom. User first defines size of the bathroom by giving dimensions. When the dimensions are defined the application renders an empty bathroom floorplan and user can start dragging&dropping furniture on to it. Some furniture have rules where they can be dragged. For example sinks can only be dragged next to a wall. I know that this functionality can be achieved with silverlight but what about html5 ? I know that Canvas element can be used to draw graphics, but can it render the bathroom smoothly as user drags a piece furniture on it?

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  • Join the Customer Revolution – 25 oct 2012 - Paris

    - by Valérie De Montvallon
    Faites redécouvrir votre marque à vos clients !   Rendez-vous le 25 octobre à 19h pour découvrir comment les outils de nouvelle génération peuvent permettre à vos équipes de proposer une nouvelle expérience client.   Table ronde animée par Arnaud le Gal, rédacteur en chef des Echos Avec les témoignages d’ACCOR et Bouygues Telecom. Informations, inscriptions sur la page Oracle Customer Experience

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  • Right mix of planning and programing on a new project

    - by WarrenFaith
    I am about to start a new project (a game, but thats unimportant). The basic idea is in my head but not all the details. I don't want to start programming without planning, but I am seriously fighting my urge to just do it. I want some planning before to prevent refactoring the whole app just because a new feature I could think of requires it. On the other hand, I don't want to plan multiple months (spare time) and start that because I have some fear that I will lose my motivation in this time. What I am looking for is a way of combining both without one dominating the other. Should I realize the project in the way of scrum? Should I creating user stories and then realize them? Should I work feature driven? (I have some experience in scrum and the classic "specification to code" way.)

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  • Using Resources the Right Way

    - by BuckWoody
    It’s an interesting time in computing technology. At one point there was a dearth of information available for solving a given problem, or educating ourselves on broader topics so that we can solve problems in the future. With dozens, perhaps hundreds or thousands of web sites and content available (for free, in many cases) from vendors, peers, even colleges and universities, it seems like there is actually too much information. Who has the time to absorb all this information and training? Even if you had the inclination, where to start? In fact, it seems so overwhelming that I often hear people saying that they can’t find the training they need, or that vendor X or Y “doesn’t help their users”. On questioning these folks, however, I often find that they – and sometimes I - haven’t put in the effort to learn what resources we have. That’s where blogs, like this one, can help. If you follow a blog, either by checking it often or perhaps subscribing to the Really Simple Syndication (RSS) feed, you’ll be able to spread out the search or create a mental filter for the information you need. But it’s not enough just read a blog or a web page. The creators need real feedback – what doesn’t work, and what does. Yes, you’re allowed to tell a vendor or writer “This helped me because…” so that you reinforce the positives. To be sure, bring up what doesn’t work as well –  that’s fine. But be specific, and be constructive. You’d be surprised at how much it matters. I know for a fact at Microsoft we listen – there is a real live person that reads your comments. I’m sure this is true of other vendors, and I also know that most blog authors – yours truly most especially – wants to know what you think.   In this blog entry I’d to call your attention to three resources you have at your disposal, and how you can use them to help. I’ll try to bring up things like this from time to time that I find useful, and cover in them in more depth like this. Think of this as a synopsis of a longer set of resources that you can use to filter whether you want to research further, bookmark, or forward on to a circle of friends where you think it might help them.   Data Driven Design Concepts http://msdn.microsoft.com/en-us/library/windowsazure/jj156154 I’ll start with a great site that walks you through the process of designing a solution from a data-first perspective. As you know, I believe all computing is merely re-arranging data. If you follow that logic as well, you’ll realize that whenever you create a solution, you should start at the data-end of the application. This resource helps you do that. Even if you don’t use the specific technologies the instructions use, the concepts hold for almost any other technology that deals with data. This should be a definite bookmark for a developer, DBA, or Data Architect. When I mentioned my admiration for this resource here at Microsoft, the team that created it contacted me and asked if I’d share an e-mail address to my readers so that you can comment on it. You’re guaranteed to be heard – you can suggest changes, talk about how useful – or not – it is, and so on. Here’s that address:  [email protected]   End-to-End Example of a complete Hybrid Application – with Live Demo https://azurestocktrader.cloudapp.net/Default.aspx I learn by example. I also like having ready-made, live, functional demos that show the completed solution at work. If you’ve ever wanted to learn how a complex, complete, hybrid application that bridges on-premises systems with cloud-based databases, code, functions and more, this is it. It’s a stock-trading simulator, and you can get everything from the design to the code itself, or you can just play with the application. It’s running on Windows Azure, the actual production servers we use for everything else. Using a Cloud-Based Service https://azureconfigweb.cloudapp.net/Default.aspx Along with that stock-trading application, you have a full demonstration and usable code sample of a web-based service available. If you’re a developer, this is a style of code you need to understand for everything from iPhone development to a full Service-Oriented Architecture (SOA) environment. So check out these resources. I’ll post more from time to time as I run across them. Hopefully they’ll be as useful to you as they are to me. Oh, and if you have a comment on any of the resources, let them know. And if you have any comments about these or any of my entries, feel free to post away. To quote a famous TV Show: “Hello Seattle – I’m listening…”

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  • Chart Chooser Helps You Pick the Right Chart for the Job

    - by Jason Fitzpatrick
    If you’re not sure what kind of chart would best showcase the data you’re presenting, Chart Chooser makes short work of narrowing it down. Are you trying to showcase trends? Compare the composition of sets? Show distributions and trends together? By selecting what you’re trying to highlight, Chart Chooser automatically narrows the pool of chart types to show which would effectively achieve your end. Once you’ve narrowed it down to the chart type you want, you can even download an Excel template for that chart type and populate it with your own data. Hit up the link below to take it for a spin and grab some free templates. Chart Chooser [via Flowing Data] How to Banish Duplicate Photos with VisiPic How to Make Your Laptop Choose a Wired Connection Instead of Wireless HTG Explains: What Is Two-Factor Authentication and Should I Be Using It?

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  • Keyword Analysis Tool - Right Method For SEO

    Keyword analysis tool have become a vital element to effective online marketing. This particular tool provides great understanding for the words and phrases people use to search the web for info and products. With that information you can make much better choices in your marketing strategies. They can help you see inside the entire market of online users.

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  • After upgrading to trusty, ALSA midi connection (aconnect) doesn't seem to work right

    - by SougonNaTakumi
    Previously in kubuntu 13.10 I was able to open vmpk or plug in a midi keyboard, and provided that TiMidity was running in server mode, I could run aconnect [keyboard port (129:0 for vmpk)] 14:0 aconnect 14:0 128:0 and I could play the keyboard and get sound. But now, a while after upgrading to trusty, I tried to do that, and didn't get any sound. TiMidity itself still plays files fine, but if I try to play them with aplaymidi, I still just get silence. Oddly, the midi files are clearly being read. When I ran (where 130:0 was vmpk's input port) aplaymidi -p 130:0 ~/path/to/midi.mid vmpk was highlighting notes on the piano as if it were playing the midi. One time I tried this, TiMidity (?) very briefly played a fraction of a second of the first chord of my song before everything went silent and vmpk just highlighted the first voice on the keyboard as usual. Now the weirdest part of this is that probably about 40% of the time, when I've played at least one note with either aplaymidi or vmpk, when I run aconnect -x I get a sudden burst of a note or chord from my speakers (that is, if I played one note, I get a note; if I played multiple sequential notes, they turn into a chord), as if the notes were being queued up but not being played and that somehow liberated them. I have no idea what's going on there. A little while ago I remember having a problem with Audacity playing wav files sped up and also locking up if I tried to pause it, which it stopped doing when I set the audio devices to the actual audio devices rather than pulse. But now when I checked again, it's doing the opposite: it won't play audio at all and/or acts weirdly if I don't set the audio devices to pulse, and either way will very occasionally randomly do the speeding up thing regardless. Oddly in the midst of what's looking like a pretty screwed up sound system, sound in VLC and Firefox has been working fine and if I play a wav file with aplay ~/path/to/sound.wav that works fine too. Any idea what I could do to figure out what's wrong with ALSA and/or fix it?

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  • Business not showing up on right hand side of google search

    - by Chris
    The business I work has currently has a verified business Google+ page and in the past this page has shown up as a thumbnail during Google searches. The thumbnail brings up basic information such as our picture and operating hours etc. However, since verifying the business page, the thumbnail overview of our business does not seem to show up anymore. I have tried Google searching our business on several computers and it still just brings up the normal search results. Is there a setting I need to activate in order for the thumbnail to appear? Thanks

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  • Dropbox indicator icon dissapears right after login

    - by garvamel
    Even though Dropbox's app indicator dissapearing from the tray area seems like a recurrent enough problem, my issue is a litte different. When I login, I can see the app panel populating, and the dropbox icon does indeed appear (config'd as startup application), but after some other icons show up (bluetooth, battery, etc.) it's gone. It's still running though. I'm guessing it's having issues with staying pinned, and I don't know how to start addressing this problem. I have tried many if not all solutions provided here in the forums for the "icon missing" questions. So far: I've whitelisted everything regarding panel Uninstalled-reinstalled (with and without rebooting in between) Overwritten current installation Purged installation from terminal Installed from Software Center and from .deb file batch deleted every "dropbox" ocurrences from terminal (files and folders) and reinstalled Ran sudo apt-get install libappindicator1, it installed, but didn't solve anything I'm on Ubuntu 12.04 LTS - 64 bits. Any insight would me much appreciated!

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  • Red Gate join the SSIS custom component club

    I recently noticed that Red Gate have launched themselves into the SSIS component market by releasing a new Data Cleanser component, albeit in beta for now. It seems to be quite a simple component, bringing together several features that you can find elsewhere, but with a suitable level  polish that you’d expect from them. String operations include find and replace with regular expressions, case formatting and trim, all of which are available today in one form or another, but will the RedGate factor appeal to people? Benefits include ease of use, all operations in one place, versus installing a custom component which many organisations do not like. I’m also interested to see where they take this and SSIS products in general, as it almost seems too simple for RedGate, a company I normally associate with more advanced problem solving. Perhaps they are just dipping a toe in the water with a simple component for now?

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  • advice for a new software engineer/developer right out of college

    - by ranzy
    I just graduated recently from a 4-year university with a degree in Computer Science and thankfully got a job in Software Engineering. I'm working with C++ with a .NET framework if that's correct to say because that also confuses me. What I'm asking for is what tutorials/books are out there to learn C++ for Windows Programming I guess? I know how to program somewhat and I understand the concepts but when I look at the code it doesn't make sense to me. I know I just started so it's kind of expected but it's certainly quite different from college. Thanks!

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  • Join me to register for the Summit

    - by Bill Graziano
    This year the Summit registration opens at 6PM on Sunday at the Seattle convention center.  Last year we had a dozen people hanging out, watching the twitter feed on the big monitor and catching up.  All we really needed was a bar and we’d have our own little party going. So this year I’m adding a bar.  I’ve arranged for a cash bar and some stand up tables.  I’m buying the first round for the first 40 or so people that come by.  Come by, register and say Hi.  I’d especially like to encourage first-time attendees to stop by.  This is a low key way to meet some people that will be at the conference.

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  • Developing Schema Compare for Oracle (Part 6): 9i Query Performance

    - by Simon Cooper
    All throughout the EAP and beta versions of Schema Compare for Oracle, our main request was support for Oracle 9i. After releasing version 1.0 with support for 10g and 11g, our next step was then to get version 1.1 of SCfO out with support for 9i. However, there were some significant problems that we had to overcome first. This post will concentrate on query execution time. When we first tested SCfO on a 9i server, after accounting for various changes to the data dictionary, we found that database registration was taking a long time. And I mean a looooooong time. The same database that on 10g or 11g would take a couple of minutes to register would be taking upwards of 30 mins on 9i. Obviously, this is not ideal, so a poke around the query execution plans was required. As an example, let's take the table population query - the one that reads ALL_TABLES and joins it with a few other dictionary views to get us back our list of tables. On 10g, this query takes 5.6 seconds. On 9i, it takes 89.47 seconds. The difference in execution plan is even more dramatic - here's the (edited) execution plan on 10g: -------------------------------------------------------------------------------| Id | Operation | Name | Bytes | Cost |-------------------------------------------------------------------------------| 0 | SELECT STATEMENT | | 108K| 939 || 1 | SORT ORDER BY | | 108K| 939 || 2 | NESTED LOOPS OUTER | | 108K| 938 ||* 3 | HASH JOIN RIGHT OUTER | | 103K| 762 || 4 | VIEW | ALL_EXTERNAL_LOCATIONS | 2058 | 3 ||* 20 | HASH JOIN RIGHT OUTER | | 73472 | 759 || 21 | VIEW | ALL_EXTERNAL_TABLES | 2097 | 3 ||* 34 | HASH JOIN RIGHT OUTER | | 39920 | 755 || 35 | VIEW | ALL_MVIEWS | 51 | 7 || 58 | NESTED LOOPS OUTER | | 39104 | 748 || 59 | VIEW | ALL_TABLES | 6704 | 668 || 89 | VIEW PUSHED PREDICATE | ALL_TAB_COMMENTS | 2025 | 5 || 106 | VIEW | ALL_PART_TABLES | 277 | 11 |------------------------------------------------------------------------------- And the same query on 9i: -------------------------------------------------------------------------------| Id | Operation | Name | Bytes | Cost |-------------------------------------------------------------------------------| 0 | SELECT STATEMENT | | 16P| 55G|| 1 | SORT ORDER BY | | 16P| 55G|| 2 | NESTED LOOPS OUTER | | 16P| 862M|| 3 | NESTED LOOPS OUTER | | 5251G| 992K|| 4 | NESTED LOOPS OUTER | | 4243M| 2578 || 5 | NESTED LOOPS OUTER | | 2669K| 1440 ||* 6 | HASH JOIN OUTER | | 398K| 302 || 7 | VIEW | ALL_TABLES | 342K| 276 || 29 | VIEW | ALL_MVIEWS | 51 | 20 ||* 50 | VIEW PUSHED PREDICATE | ALL_TAB_COMMENTS | 2043 | ||* 66 | VIEW PUSHED PREDICATE | ALL_EXTERNAL_TABLES | 1777K| ||* 80 | VIEW PUSHED PREDICATE | ALL_EXTERNAL_LOCATIONS | 1744K| ||* 96 | VIEW | ALL_PART_TABLES | 852K| |------------------------------------------------------------------------------- Have a look at the cost column. 10g's overall query cost is 939, and 9i is 55,000,000,000 (or more precisely, 55,496,472,769). It's also having to process far more data. What on earth could be causing this huge difference in query cost? After trawling through the '10g New Features' documentation, we found item 1.9.2.21. Before 10g, Oracle advised that you do not collect statistics on data dictionary objects. From 10g, it advised that you do collect statistics on the data dictionary; for our queries, Oracle therefore knows what sort of data is in the dictionary tables, and so can generate an efficient execution plan. On 9i, no statistics are present on the system tables, so Oracle has to use the Rule Based Optimizer, which turns most LEFT JOINs into nested loops. If we force 9i to use hash joins, like 10g, we get a much better plan: -------------------------------------------------------------------------------| Id | Operation | Name | Bytes | Cost |-------------------------------------------------------------------------------| 0 | SELECT STATEMENT | | 7587K| 3704 || 1 | SORT ORDER BY | | 7587K| 3704 ||* 2 | HASH JOIN OUTER | | 7587K| 822 ||* 3 | HASH JOIN OUTER | | 5262K| 616 ||* 4 | HASH JOIN OUTER | | 2980K| 465 ||* 5 | HASH JOIN OUTER | | 710K| 432 ||* 6 | HASH JOIN OUTER | | 398K| 302 || 7 | VIEW | ALL_TABLES | 342K| 276 || 29 | VIEW | ALL_MVIEWS | 51 | 20 || 50 | VIEW | ALL_PART_TABLES | 852K| 104 || 78 | VIEW | ALL_TAB_COMMENTS | 2043 | 14 || 93 | VIEW | ALL_EXTERNAL_LOCATIONS | 1744K| 31 || 106 | VIEW | ALL_EXTERNAL_TABLES | 1777K| 28 |------------------------------------------------------------------------------- That's much more like it. This drops the execution time down to 24 seconds. Not as good as 10g, but still an improvement. There are still several problems with this, however. 10g introduced a new join method - a right outer hash join (used in the first execution plan). The 9i query optimizer doesn't have this option available, so forcing a hash join means it has to hash the ALL_TABLES table, and furthermore re-hash it for every hash join in the execution plan; this could be thousands and thousands of rows. And although forcing hash joins somewhat alleviates this problem on our test systems, there's no guarantee that this will improve the execution time on customers' systems; it may even increase the time it takes (say, if all their tables are partitioned, or they've got a lot of materialized views). Ideally, we would want a solution that provides a speedup whatever the input. To try and get some ideas, we asked some oracle performance specialists to see if they had any ideas or tips. Their recommendation was to add a hidden hook into the product that allowed users to specify their own query hints, or even rewrite the queries entirely. However, we would prefer not to take that approach; as well as a lot of new infrastructure & a rewrite of the population code, it would have meant that any users of 9i would have to spend some time optimizing it to get it working on their system before they could use the product. Another approach was needed. All our population queries have a very specific pattern - a base table provides most of the information we need (ALL_TABLES for tables, or ALL_TAB_COLS for columns) and we do a left join to extra subsidiary tables that fill in gaps (for instance, ALL_PART_TABLES for partition information). All the left joins use the same set of columns to join on (typically the object owner & name), so we could re-use the hash information for each join, rather than re-hashing the same columns for every join. To allow us to do this, along with various other performance improvements that could be done for the specific query pattern we were using, we read all the tables individually and do a hash join on the client. Fortunately, this 'pure' algorithmic problem is the kind that can be very well optimized for expected real-world situations; as well as storing row data we're not using in the hash key on disk, we use very specific memory-efficient data structures to store all the information we need. This allows us to achieve a database population time that is as fast as on 10g, and even (in some situations) slightly faster, and a memory overhead of roughly 150 bytes per row of data in the result set (for schemas with 10,000 tables in that means an extra 1.4MB memory being used during population). Next: fun with the 9i dictionary views.

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  • How to Choose the Right Web Development Services Provider For Outsourcing

    Many a times you are confronted with situations where the work at your hand is more than what your in-house professionals can accomplish. Again there may be times when you can accomplish the work by your individual effort but that will keep you diverted from your core activities like business development, finance management etc. In such situations, outsourcing your web development services could be an attractive choice.

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