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  • What Counts For a DBA: Fitness

    - by Louis Davidson
    If you know me, you can probably guess that physical exercise is not really my thing. There was a time in my past when it a larger part of my life, but even then never in the same sort of passionate way as a number of our SQL friends.  For me, I find that mental exercise satisfies what I believe to be the same inner need that drives people to run farther than I like to drive on most Saturday mornings, and it is certainly just as addictive. Mental fitness shares many common traits with physical fitness, especially the need to attain it through repetitive training. I only wish that mental training burned off a bacon cheeseburger in the same manner as does jogging around a dewy park on Saturday morning. In physical training, there are at least two goals, the first of which is to be physically able to do a task. The second is to train the brain to perform the task without thinking too hard about it. No matter how long it has been since you last rode a bike, you will be almost certainly be able to hop on and start riding without thinking about the process of pedaling or balancing. If you’ve never ridden a bike, you could be a physics professor /Olympic athlete and still crash the first few times you try, even though you are as strong as an ox and your knowledge of the physics of bicycle riding makes the concept child’s play. For programming tasks, the process is very similar. As a DBA, you will come to know intuitively how to backup, optimize, and secure database systems. As a data programmer, you will work to instinctively use the clauses of Transact-SQL DML so that, when you need to group data three ways (and not four), you will know to use the GROUP BY clause with GROUPING SETS without resorting to a search engine.  You have the skill. Making it naturally then requires repetition and experience is the primary requirement, not just simply learning about a topic. The hardest part of being really good at something is this difference between knowledge and skill. I have recently taken several informative training classes with Kimball University on data warehousing and ETL. Now I have a lot more knowledge about designing data warehouses than before. I have also done a good bit of data warehouse designing of late and have started to improve to some level of proficiency with the theory. Yet, for all of this head knowledge, it is still a struggle to take what I have learned and apply it to the designs I am working on.  Data warehousing is still a task that is not yet deeply ingrained in my brain muscle memory. On the other hand, relational database design is something that no matter how much or how little I may get to do it, I am comfortable doing it. I have done it as a profession now for well over a decade, I teach classes on it, and I also have done (and continue to do) a lot of mental training beyond the work day. Sometimes the training is just basic education, some reading blogs and attending sessions at PASS events.  My best training comes from spending time working on other people’s design issues in forums (though not nearly as much as I would like to lately). Working through other people’s problems is a great way to exercise your brain on problems with which you’re not immediately familiar. The final bit of exercise I find useful for cultivating mental fitness for a data professional is also probably the nerdiest thing that I will ever suggest you do.  Akin to running in place, the idea is to work through designs in your head. I have designed more than one database system that would revolutionize grocery store operations, sales at my local Target store, the ordering process at Amazon, and ways to improve Disney World operations to get me through a line faster (some of which they are starting to implement without any of my help.) Never are the designs truly fleshed out, but enough to work through structures and processes.  On “paper”, I have designed database systems to catalog things as trivial as my Lego creations, rental car companies and my audio and video collections. Once I get the database designed mentally, sometimes I will create the database, add some data (often using Red-Gate’s Data Generator), and write a few queries to see if a concept was realistic, but I will rarely fully flesh out the database since I have no desire to do any user interface programming anymore.  The mental training allows me to keep in practice for when the time comes to do the work I love the most for real…even if I have been spending most of my work time lately building data warehouses.  If you are really strong of mind and body, perhaps you can mix a mental run with a physical run; though don’t run off of a cliff while contemplating how you might design a database to catalog the trees on a mountain…that would be contradictory to the purpose of both types of exercise.

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  • Programming for the iPhone

    - by Bobby Alexander
    Whats the best way to get started on iPhone development if you are an expeienced C++ or C# programmer? Most books either assume you know nothing or something. What are the steps to achieve this? For eg: first learn objective C (let's say), next learn cocoa... I am interested in books/resources. I read Getting started with iPhone development from Oreilly (the missing manuals book) but that just provided an over view on the programming and concentrated more on getting your app into the app store. I need need resources that will help be start coding. Other questions: How much of objective C do you need to know? How do go ahead with learning the cocoa framework? Can I directly start on cocoa touch or do I need to know the MAC cocoa framework first? Inputs from someone who was in the same situation (Know c++/c# but no clue about mac programming/objective c/cocoa) would help greatly.

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  • Run Blustacks or Android to play clash of clans on ubuntu 13.4+

    - by Joe Hanus
    I am trying to get rid of the need to dual boot Ubuntu and windows and one thing I can do with windows I can not do with Linux is to run Bluestacks to play android games my favourite one ow is clash of clans. I have tried different VM's to run android emulators and virtual box but nothing works for clash of clans I can download the game to the VM from Google Play Store but it fails to open If Ubuntu can fix this by making a way to successfully install Bluestacks on Ubuntu or Android with Virtual box with out loading errors of all apps/games it would help the Linux community to become less dependant of Windows. Thanks in advance! go Ubuntu!

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  • Finding it Hard to Deliver Right Customer Experience: Think BPM!

    - by Ajay Khanna
    Our relationship with our customers is not a just a single interaction and we should not treat it like one. A customer’s relationship with a vendor is like a journey which starts way before customer makes a purchase and lasts long after that. The journey may start with customer researching a product that may lead to the eventual purchase and may continue with support or service needs for the product. A typical customer journey can be represented as shown below: As you may notice, customers tend to use multiple channels to interact with a company throughout their journey.  They also expect that they should get consistent experience, no matter what interaction channel they may choose. Customers do not like to repeat the information they have already provided and expect companies to remember their preferences, and offer them relevant products and services. If the company fails to meet this expectation, customers not only will abandon the purchase and go to the competitor but may also influence others’ purchase decision. Gone are the days when word of mouth was the only medium, and the customer could influence “Six” others. This is the age of social media and customer’s good or bad experience, especially bad get highly amplified and may influence hundreds of others. Challenges that face B2C companies today include: Delivering consistent experience: The reason that delivering consistent experience is challenging is due to fragmented data, disjointed systems and siloed multichannel interactions. Customers tend to get different service quality if they use web vs. phone vs. store. They get different responses from different service agents or get inconsistent answers if they call sales vs. service group in the company. Such inconsistent experiences result in lower customer satisfaction or NPS (net promoter score) numbers. Increasing Revenue: To stay competitive companies frequently introduce new products and services. Delay in launching such offerings has a significant impact on revenue realization. In addition to new product revenue, there are multiple opportunities to up-sell and cross-sell that impact bottom line. If companies are not able to identify such opportunities, bring a product to market quickly, or not offer the right product to the right customer at the right time, significant loss of revenue may occur. Ensuring Compliance: Companies must be compliant to ever changing regulations, these could be about Know Your Customer (KYC), Export/Import regulations, or taxation policies. In addition to government agencies, companies also need to comply with the SLA that they have committed to their customers. Lapse in meeting any of these requirements may lead to serious fines, penalties and loss in business. Companies have to make sure that they are in compliance will all such regulations and SLA commitments, at any given time. With the advent of social networks and mobile technology, companies not only need to focus on process efficiency but also on customer engagement. Improving engagement means delivering the customer experience as the customer is expecting and interacting with the customer at right time using right channel. Customers expect to be able to contact you via any channel of their choice (web, email, chat, mobile, social media), purchase via any viable channel (web, phone, store, mobile). Customers expect companies to understand their particular needs and remember their preferences on repeated visits. To deliver such an integrated, consistent, and contextual experience, power of BPM in must. Your company may be organized in departments like Marketing, Sales, Service. You may hold prospect data in SFA, order information in ERP, customer issues in CRM. However, the experience delivered to the customer must not be constrained by your system legacy. BPM helps in designing the right experience for the right customer and integrates all the underlining channels, systems, applications to make sure right information will be delivered to the right knowledge worker or to the customer every single time.     Orchestrating information across all systems (MDM, CRM, ERP), departments (commerce, merchandising, marketing service) and channels (Email, phone, web, social)  is the key, and that’s what BPM delivers. In addition to orchestrating systems and channels for consistency, BPM also provides an ability for analysis and decision management. By using data from historical transactions, social media and from other systems, users can determine the customer preferences, customer value, and churn propensity. This information, in the context, is then used while making a decision at a process step. Working with real-time decision management system can also suggest right up-sell or cross-sell offers, discounts or next-best-action steps for a particular customer. Timely action on customer issues or request is also a key tenet of a good customer experience. BPM’s complex event processing capabilities help companies to take proactive actions before issues get escalated. BPM system can be designed to listen to a certain event patters then deduce from those customer situations (credit card stolen, baggage lost, change of address) and do a triage before situation goes out of control. If such a situation arises you can send alerts to right people or immediately invoke corrective actions. Last but not least one of BPM’s key values is to drive continuous improvement. Learning about customers past experiences, interactions and social conversations, provide valuable insight. Such insight can be used to improve products, customer facing processes, and customer experience. You may take these insights as an input to design better more efficient and customer friendly sales, contact center or self-service processes. If customer experience is important for your business, make sure you have incorporated BPM as a part of your strategy to design, orchestrate and improve your customer facing processes.

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  • My Feelings About Microsoft Surface

    - by Valter Minute
    Advice: read the title carefully, I’m talking about “feelings” and not about advanced technical points proved in a scientific and objective way I still haven’t had a chance to play with a MS Surface tablet (I would love to, of course) and so my ideas just came from reading different articles on the net and MS official statements. Remember also that the MVP motto begins with “Independent” (“Independent Experts. Real World Answers.”) and this is just my humble opinion about a product and a technology. I know that, being an MS MVP you can be called an “MS-fanboy”, I don’t care, I hope that people can appreciate my opinion, even if it doesn’t match theirs. The “Surface” brand can be confusing for techies that knew the “original” surface concept but I think that will be a fresh new brand name for most of the people out there. But marketing department are here to confuse people… so I can understand this “recycle” of an existing name. So Microsoft is entering the hardware arena… for me this is good news. Microsoft developed some nice hardware in the past: the xbox, zune (even if the commercial success was quite limited) and, last but not least, the two arc mices (old and new model) that I use and appreciate. In the past Microsoft worked with OEMs and that model lead to good and bad things. Good thing (for microsoft, at least) is market domination by windows-based PCs that only in the last years has been reduced by the return of the Mac and tablets. Google is also moving in the hardware business with its acquisition of Motorola, and Apple leveraged his control of both the hardware and software sides to develop innovative products. Microsoft can scare OEMs and make them fly away from windows (but where?) or just lead the pack, showing how devices should be designed to compete in the market and bring back some of the innovation that disappeared from recent PC products (look at the shelves of your favorite electronics store and try to distinguish a laptop between the huge mass of anonymous PCs on displays… only Macs shine out there…). Having to compete with MS “official” hardware will force OEMs to develop better product and bring back some real competition in a market that was ruled only by prices (the lower the better even when that means low quality) and no innovative features at all (when it was the last time that a new PC surprised you?). Moving into a new market is a big and risky move, but with Windows 8 Microsoft is playing a crucial move for its future, trying to be back in the innovation run against apple and google. MS can’t afford to fail this time. I saw the new devices (the WinRT and Pro) and the specifications are scarce, misleading and confusing. The first impression is that the device looks like an iPad with a nice keyboard cover… Using “HD” and “full HD” to define display resolution instead of using the real figures and reviving the “ClearType” brand (now dead on Win8 as reported here and missed by people who hate to read text on displays, like myself) without providing clear figures (couldn’t you count those damned pixels?) seems to imply that MS was caught by surprise by apple recent “retina” displays that brought very high definition screens on tablets.Also there are no specifications about the processors used (even if some sources report NVidia Tegra for the ARM tablet and i5 for the x86 one) and expected battery life (a critical point for tablets and the point that killed Windows7 x86 based tablets). Also nothing about the price, and this will be another critical point because other platform out there already provide lots of applications and have a good user base, if MS want to enter this market tablets pricing must be competitive. There are some expansion ports (SD and USB), so no fixed storage model (even if the specs talks about 32-64GB for RT and 128-256GB for pro). I like this and don’t like the apple model where flash memory (that it’s dirt cheap used in thumdrives or SD cards) is as expensive as gold (or cocaine to have a more accurate per gram measurement) when mounted inside a tablet/phone. For big files you’ll be able to use external media and an SD card could be used to store files that don’t require super-fast SSD-like access times, I hope. To be honest I really don’t like the marketplace model and the limitation of Windows RT APIs (no local database? from a company that based a good share of its success on VB6+Access!) and lack of desktop support on the ARM (even if the support is here and has been used to port office). It’s a step toward the consumer market (where competitors are making big money), but may impact enterprise (and embedded) users that may not appreciate Windows 8 new UI or the limitations of the new app model (if you aren’t connected you are dead ). Not having compatibility with the desktop will require brand new applications and honestly made all the CPU cycles spent to convert .NET IL into real machine code in the past like a huge waste of time… as soon as a new processor architecture is supported by Windows you still have to rewrite part of your application (and MS is pushing HTML5+JS and native code more than .NET in my perception). On the other side I believe that the development experience provided by Visual Studio is still miles (or kilometres) ahead of the competition and even the all-uppercase menu of VS2012 hasn’t changed this situation. The new metro UI got mixed reviews. On my side I should say that is very pleasant to use on a touch screen, I like the minimalist design (even if sometimes is too minimal and hides stuff that, in my opinion, should be visible) but I should also say that using it with mouse and keyboard is like trying to pick your nose with boxing gloves… Metro is also very interesting for embedded devices where touch screen usage is quite common and where having an application taking all the screen is the norm. For devices like kiosks, vending machines etc. this kind of UI can be a great selling point. I don’t need a new tablet (to be honest I’m pretty happy with my wife’s iPad and with my PC), but I may change my opinion after having a chance to play a little bit with those new devices and understand what’s hidden under all this mysterious and generic announcements and specifications!

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  • What is the difference between all-static-methods and applying a singleton pattern?

    - by shahensha
    I am making a database to store information about the users of my website (I am using stuts2 and hence Java EE technology). For the database I'll be making a DBManager. Should I apply singleton pattern here or rather make all it's methods static? I will be using this DBManager for basic things like adding, deleting and updating User profiles. Along with it, I'll use for all other querying purposes, for instance to find out whether a username already exists and to get all users for administrative purposes and stuff like that. My questions What is the benefit of singleton pattern? Which thing is most apt here? All static methods or a singleton pattern? Please compare both of them. regards shahensha P.S. The database is bigger than this. Here I am talking only about the tables which I'll be using for storing User Information.

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  • How to derive euler angles from matrix or quaternion?

    - by KlashnikovKid
    Currently working on steering behavior for my AI and just hit a little mathematical bump. I'm in the process of writing an align function, which basically tries to match the agent's orientation with a target orientation. I've got a good source material for implementing this behavior but it uses euler angles to calculate the rotational delta, acceleration, and so on. This is nice, however I store orientation as a quaternion and the math library I'm using doesn't provide any functionality for deriving the euler angles. But if it helps I also have rotational matrices at my disposal too. What would be the best way to decompose the quaternion or rotational matrix to get the euler information? I found one source for decomposing the matrix, but I'm not quite getting the correct results. I'm thinking it may be a difference of column/row ordering of my matrices but then again, math isn't my strong point. http://nghiaho.com/?page_id=846

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  • DLNA Media Server and external subtitles

    - by Lobo
    I'm looking DLNA Media Server with the features above: Support most extended video formats. Reproduce external subtitles in client side. Open source or freeware software. USE CASE: DLNA Media server installed and running on my PC. In my PC, I have /home/myprofile/videos directory where I store all my video files. For example, game.of.thrones.s09.e06.mpg and game.of.thrones.s09.e06.srt Turn on my Smart-TV, connect to my DLNA Media Server (installed on my PC) Play game.of.thrones.s09.e06.mpg file and see the subtitles overlapped. Finally, my question: Is there some DLNA Media server that provides that use case?. Thank you.

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  • Be careful when Git suppresses bin Folders

    - by Marko Apfel
    Initial situation Often for Visual Studio projects the typical content of a .gitignore file contains this line bin or [B|b]in It is used to avoid that Git tries to track compile outputs as repository relevant data. Problem But keep in mind: this will also suppress bin folders of additional stuff like frameworks and toolsets. For instance Microsoft.SDKs contains a folder named Bin with a lot of programs Simian contains a folder named bin with the program themselves If you store such artifacts also in the repository - according to the principle of a “self containing project” – you could lost the content in the bin folder! Solution Till yet I don’t have a good idea. So I verify for each new added toolset or framework whether it has or has not such a bin folder. If it has, then I must add this bin folder manually to the repository so that Git track it.

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  • Rendering order in an Entity System

    - by Daedalus
    Say I use a basic ES approach, and also inside Systems I hold lists of all entities that Systems are required to process. How do I maintain this list of entities in desired rendering order, i.e. for a dumb 2D RenderingSystem? I saw this discussion, and what they suggest is to do something like Z ordering - what I would probably do is just to store a "layer" int in DrawableComponent and then, inside RenderingSystem, just sort entities by mentioned "layer" whenever the entity list for RenderingSystem changes. They also say we could just delete and recreate the entity whenever we want it on the top, but it seems too inflexible to me. How is this problem usually solved?

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  • Best accounting software for freelance/contractor programmer? [closed]

    - by user1352034
    I know this isn't exactly a programming question but I am hoping to find some programmers who freelance or do contractor work in the US. I have started to work on side jobs and have been billing my clients using Paypal. I then would store those records in a Google excel doc but realize this will get out of hand as time goes on and am looking for a good solution. I am no accountant so I am not sure of everything I would need but I am guessing basic invoicing, expenses, reporting, integration with paypal, etc.. Any contractors or freelancers in here could recommend what they use? I have researched a few but would like to hear what other people are using and how it is working out for them. Thanks for your time!

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  • How to design a separated tutorial mode?

    - by Sylpheed
    I'm working on a "social" game that's about 90% completion. One of the remaining features is the tutorial mode. Basically, the tutorial mode will restrict the user to access some parts of UI and limit the features (like store items). The tutorial will only progress if a certain event is triggered, specifically following the tutorial. The code is ready and we already have an "almost" working game. The problem is I haven't foreseen the tutorial mode while I was doing those 90%. My requirement is there shouldn't be any loading/transition from tutorial mode to normal mode. This means I have to pick up the progress from the tutorial (no re-rendering of assets and stuff). How should I design this in a way where I won't touch anything from my old code? I want it to be as easy as just plugging it in. I don't want to jam the tutorial in my old code since this will lead to many bugs.

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  • ways to program glitch style effects

    - by okkk
    Most tutorials for generating glitch art usually has to do with some form of manipulation of the compression of files. Should my goal instead to replicate the look of these glitches in shaders or is it somehow possible to authentically generate the compression artifacts in real time? Example: This effect which I'm particularly interested is referred to as datamoshing. It does "things" using the p-frames of a video (frames that I think store just the change in pixels). I feel like I need a better understanding of both graphics programming and data-compression.

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  • Strange sound issues with Ubuntu 11.10

    - by DNA
    I am having strange issues with sound and volume with Ubuntu 11.10 I've noticed very often, especially when I get my computer out of sleep, it lacks sound even though the volume slider is cranked all the way up. But when I plug my headphones in and then take them out, it seems to kick start my sound back! What gives? What daemon in /etc/int.d needs to be restared with the restart command to fix this? I have the following in my init.d folder /etc/init.d/alsa-restore and /etc/init.d/alsa-store Also, my start up ubuntu sound doesn't play either....

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  • Building an web/ mobile app like instagram [on hold]

    - by John
    I would like to build an app like instagram or twitter. User can upload photo, type a few words, hashtag, share their location. And there will be a page like newsfeed showing updates. User can login with oauth. How do I store those data especially photos? (In those cloud thins? like Google cloud? I don't know how those cloud works) and what is the cost of it (if can compress user uploaded photos?). I currently only knows php, javascript and mysql.

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  • Track those visitors who come through a particular link

    - by busybee235
    I want to track visitors who come to my site through a particular link. For example, those visitors coming from http://www.domain.com/abc123, I can get their pageviews, time on site, bounce rate, referrer pages per visit etc. After that I can store that info into by database on daily basis. Can anyone suggest any service or api or any software for the same? I have used Google Analytics utm tags that work straight well for my requirement but I don't know how many links I can track with it. I have around 80-100 links to track a day and the number of links will be increasing. I couldn't find any documentation regarding limit of campaigns in GA. If there's no such limit, I can start this project. Thanks

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  • ".ts " files not recognised

    - by Keith Gardner
    I have some .ts files (programs recorded from my Sharp TV on USB stick) that I want to store/play on my PC. However, although they are listed on the stick when its plugged in the PC nothing will recognize the files. I have tried VLC (the "slider" moves but there's no sound or video) and changed the extension to MPEG, MP2, etc. but no joy. I have tried converting the files with file converters and demuxers but none of these recognize the files. Are the files corrupted (they play on the TV) or do Sharp have a unique file structure? Any help would be greatly appreciated.

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  • Google I/O 2010 - Cloud computing for geospatial apps

    Google I/O 2010 - Cloud computing for geospatial apps Google I/O 2010 - Unleash your map data: Cloud computing for geospatial applications Geo 101 Tom Manshreck The Google Maps API made geospatial development accessible to all but hosting your data remains complex and time consuming. This session will detail the services Google offers for storing your geospatial data in the cloud, illustrate the ways in which that data can be accessed and visualized, and walk through development of a retail store finder using these technologies. For all I/O 2010 sessions, please go to code.google.com From: GoogleDevelopers Views: 322 0 ratings Time: 40:22 More in Science & Technology

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  • How to Create a Custom Refresh Image in Windows 8

    - by Taylor Gibb
    We have already shown you how to use the Refresh and Reset features in Windows 8, now we are back to show you how you can create a custom refresh image. This means next time you refresh your Windows 8 PC, you can use a custom image instead of the one that shipped with your PC. When you refresh your PC, all your files as well as Metro applications that you downloaded from the Windows store are kept. This is great, however, all your non-metro applications and PC settings are removed. If you are like me and have a lot of non-metro apps this can be very annoying, but you can fix this by creating a refresh image that already has your apps installed and your settings tweaked. 6 Start Menu Replacements for Windows 8 What Is the Purpose of the “Do Not Cover This Hole” Hole on Hard Drives? How To Log Into The Desktop, Add a Start Menu, and Disable Hot Corners in Windows 8

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  • Structure of a correctly implemented JTable with TableModel and Listeners?

    - by bamboocha
    I am pretty new to Java and its JTables and this is where I am struggling at the moment. I need to create a GUI which shows me results of a sql query like SELECT * FROM tblPeople WHERE name='Doe'. My idea was to create a a JFrame which displays a JTable with all found records. Besides this, I need to also implement some code to handle when a user is double clicking a record or selecting it by using his arrow keys (additional feature: pressing 12(e.g.) should select the 12th record). What is the best way to structure my program (what classes do I need and especially where do I store my logic)? I came up with structuring it the following way: Main.java ("view") SQLConnection.java PeopleTableModel.java (only stores and returns data given by the passed ResultSet, "model" inherits from DefaultTableModel) PeopleTable.java (stores basically all my logic including KeyListener and MouseListener, "controller", inherits from JTable) Are there better ways to achieve my goals? If so, what are they?

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  • Oracle NoSQL Database Exceeds 1 Million Mixed YCSB Ops/Sec

    - by Charles Lamb
    We ran a set of YCSB performance tests on Oracle NoSQL Database using SSD cards and Intel Xeon E5-2690 CPUs with the goal of achieving 1M mixed ops/sec on a 95% read / 5% update workload. We used the standard YCSB parameters: 13 byte keys and 1KB data size (1,102 bytes after serialization). The maximum database size was 2 billion records, or approximately 2 TB of data. We sized the shards to ensure that this was not an "in-memory" test (i.e. the data portion of the B-Trees did not fit into memory). All updates were durable and used the "simple majority" replica ack policy, effectively 'committing to the network'. All read operations used the Consistency.NONE_REQUIRED parameter allowing reads to be performed on any replica. In the past we have achieved 100K ops/sec using SSD cards on a single shard cluster (replication factor 3) so for this test we used 10 shards on 15 Storage Nodes with each SN carrying 2 Rep Nodes and each RN assigned to its own SSD card. After correcting a scaling problem in YCSB, we blew past the 1M ops/sec mark with 8 shards and proceeded to hit 1.2M ops/sec with 10 shards.  Hardware Configuration We used 15 servers, each configured with two 335 GB SSD cards. We did not have homogeneous CPUs across all 15 servers available to us so 12 of the 15 were Xeon E5-2690, 2.9 GHz, 2 sockets, 32 threads, 193 GB RAM, and the other 3 were Xeon E5-2680, 2.7 GHz, 2 sockets, 32 threads, 193 GB RAM.  There might have been some upside in having all 15 machines configured with the faster CPU, but since CPU was not the limiting factor we don't believe the improvement would be significant. The client machines were Xeon X5670, 2.93 GHz, 2 sockets, 24 threads, 96 GB RAM. Although the clients had 96 GB of RAM, neither the NoSQL Database or YCSB clients require anywhere near that amount of memory and the test could have just easily been run with much less. Networking was all 10GigE. YCSB Scaling Problem We made three modifications to the YCSB benchmark. The first was to allow the test to accommodate more than 2 billion records (effectively int's vs long's). To keep the key size constant, we changed the code to use base 32 for the user ids. The second change involved to the way we run the YCSB client in order to make the test itself horizontally scalable.The basic problem has to do with the way the YCSB test creates its Zipfian distribution of keys which is intended to model "real" loads by generating clusters of key collisions. Unfortunately, the percentage of collisions on the most contentious keys remains the same even as the number of keys in the database increases. As we scale up the load, the number of collisions on those keys increases as well, eventually exceeding the capacity of the single server used for a given key.This is not a workload that is realistic or amenable to horizontal scaling. YCSB does provide alternate key distribution algorithms so this is not a shortcoming of YCSB in general. We decided that a better model would be for the key collisions to be limited to a given YCSB client process. That way, as additional YCSB client processes (i.e. additional load) are added, they each maintain the same number of collisions they encounter themselves, but do not increase the number of collisions on a single key in the entire store. We added client processes proportionally to the number of records in the database (and therefore the number of shards). This change to the use of YCSB better models a use case where new groups of users are likely to access either just their own entries, or entries within their own subgroups, rather than all users showing the same interest in a single global collection of keys. If an application finds every user having the same likelihood of wanting to modify a single global key, that application has no real hope of getting horizontal scaling. Finally, we used read/modify/write (also known as "Compare And Set") style updates during the mixed phase. This uses versioned operations to make sure that no updates are lost. This mode of operation provides better application behavior than the way we have typically run YCSB in the past, and is only practical at scale because we eliminated the shared key collision hotspots.It is also a more realistic testing scenario. To reiterate, all updates used a simple majority replica ack policy making them durable. Scalability Results In the table below, the "KVS Size" column is the number of records with the number of shards and the replication factor. Hence, the first row indicates 400m total records in the NoSQL Database (KV Store), 2 shards, and a replication factor of 3. The "Clients" column indicates the number of YCSB client processes. "Threads" is the number of threads per process with the total number of threads. Hence, 90 threads per YCSB process for a total of 360 threads. The client processes were distributed across 10 client machines. Shards KVS Size Clients Mixed (records) Threads OverallThroughput(ops/sec) Read Latencyav/95%/99%(ms) Write Latencyav/95%/99%(ms) 2 400m(2x3) 4 90(360) 302,152 0.76/1/3 3.08/8/35 4 800m(4x3) 8 90(720) 558,569 0.79/1/4 3.82/16/45 8 1600m(8x3) 16 90(1440) 1,028,868 0.85/2/5 4.29/21/51 10 2000m(10x3) 20 90(1800) 1,244,550 0.88/2/6 4.47/23/53

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  • How to avoid or minimise use of check/conditional statement in my scenario?

    - by Muneeb Nasir
    I have scenario, where I got stream and I need to check for some value. If I got any new value I have to store it in any of data structure. It seems very easy, I can place conditional statement if-else or can use contain method of set/map to check either received is new or not. But the problem is checking will effect my application performance, in stream I will receive hundreds for value in second, if I start checking each and every value I received then for sure it effect performance. Anybody can suggest me any mechanism or algorithm to solve my issue, either by bypassing checks or at least minimize them?

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  • How to display image in html image tag - node.js [on hold]

    - by ykel
    I use the following code to store image to file system and to retrieve the image, I would like to display the retrieved image on html image tag, hower the image is rendered on the response page but not on the html image tag. here is my html image tag: <img src="/show"> THIS CODE RETREIVES THE IMAGE: app.get('/show', function (req, res) { var FilePath=__dirname+"/uploads/3562_564927103528411_1723183324_n.jpg"; fs.readFile(FilePath,function(err,data){ if(err)throw err; console.log(data); res.writeHead(200, {'Content-Type': 'image/jpeg'}); res.end(data); // Send the file data to the browser. }) });

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  • Google Analytics - TOS section pertaining to privacy

    - by Eike Pierstorff
    The Google Analytics terms of service does do not allow to track "data that personally identifies an individual (such as a name, email address or billing information), or other data which can be reasonably linked to such information by Google". Does anybody have first-hand knowledge if this includes user ids which cannot be resolved by Google but can be linked to actual persons via an Analytics Users CRM system (e.g. a CRM linked to Analytics via API access) ? I used to think so, but if that where the case many ecommerce implementations would be illegal (since they store transactions id which can be linked to client's purchases). If anybody has insights about the intended meaning of the paragraph (preferably with a reliable source) it would be great if he/she could share :-)

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  • Google I/O 2012 - Writing Polished Apps that have Deep Integration into the Google Drive UI

    Google I/O 2012 - Writing Polished Apps that have Deep Integration into the Google Drive UI Mike Procopio, Steve Bazyl We'll go through how to implement complete Drive apps. This is not an introduction to Drive apps, but rather how to build your product into Google Drive, and ensure that the experience is seamless for a user. We will also discuss how to effectively distribute your app in the Chrome Web Store. The example app built in this talk will demonstrate an example use case, but otherwise be production-ready. For all I/O 2012 sessions, go to developers.google.com From: GoogleDevelopers Views: 829 5 ratings Time: 50:59 More in Science & Technology

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