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  • Proper way to measure the scalability of web Application

    - by Jorge
    Let's say that I have a web Application where i'm going to have 300 users and each one have to see data on real time, imagine that each client make an ajax call to the server to see in real time what's happens with the changes of the data, this calls are made each 300 ms per user. I know that i can run a simulation to see if the hardware of my server supports this example. But what happen's if the number of users start to grow up. Is there a way that i can measure the hardware needed to handle this growing behavior, a software, a formula, algorithm or maybe recommend me if i need to implement an distributed application with multiplies servers and balance the loads.

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  • How to evaluate SEO/prominence improvement [on hold]

    - by Rober
    I will work on a website SEO and before starting with it I would like to "take a snapshot" of the present status so that I will be able to compare it with the new situation in a few months and evaluate my work and the real improvement. I don't mean whether the website is well implemented or not, but how well it is seen by Google and others. What prominence it has. I am taking some variables from Google Analytics (average day visits...), from Google Webmaster Tools (Search traffic and average position...) and some other indicators, like automatic SEO audit figures (website estimated worth, real pagerank...). What would you look at before starting SEO improvement?

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  • Solving Big Problems with Oracle R Enterprise, Part I

    - by dbayard
    Abstract: This blog post will show how we used Oracle R Enterprise to tackle a customer’s big calculation problem across a big data set. Overview: Databases are great for managing large amounts of data in a central place with rigorous enterprise-level controls.  R is great for doing advanced computations.  Sometimes you need to do advanced computations on large amounts of data, subject to rigorous enterprise-level concerns.  This blog post shows how Oracle R Enterprise enables R plus the Oracle Database enabled us to do some pretty sophisticated calculations across 1 million accounts (each with many detailed records) in minutes. The problem: A financial services customer of mine has a need to calculate the historical internal rate of return (IRR) for its customers’ portfolios.  This information is needed for customer statements and the online web application.  In the past, they had solved this with a home-grown application that pulled trade and account data out of their data warehouse and ran the calculations.  But this home-grown application was not able to do this fast enough, plus it was a challenge for them to write and maintain the code that did the IRR calculation. IRR – a problem that R is good at solving: Internal Rate of Return is an interesting calculation in that in most real-world scenarios it is impractical to calculate exactly.  Rather, IRR is a calculation where approximation techniques need to be used.  In this blog post, we will discuss calculating the “money weighted rate of return” but in the actual customer proof of concept we used R to calculate both money weighted rate of returns and time weighted rate of returns.  You can learn more about the money weighted rate of returns here: http://www.wikinvest.com/wiki/Money-weighted_return First Steps- Calculating IRR in R We will start with calculating the IRR in standalone/desktop R.  In our second post, we will show how to take this desktop R function, deploy it to an Oracle Database, and make it work at real-world scale.  The first step we did was to get some sample data.  For a historical IRR calculation, you have a balances and cash flows.  In our case, the customer provided us with several accounts worth of sample data in Microsoft Excel.      The above figure shows part of the spreadsheet of sample data.  The data provides balances and cash flows for a sample account (BMV=beginning market value. FLOW=cash flow in/out of account. EMV=ending market value). Once we had the sample spreadsheet, the next step we did was to read the Excel data into R.  This is something that R does well.  R offers multiple ways to work with spreadsheet data.  For instance, one could save the spreadsheet as a .csv file.  In our case, the customer provided a spreadsheet file containing multiple sheets where each sheet provided data for a different sample account.  To handle this easily, we took advantage of the RODBC package which allowed us to read the Excel data sheet-by-sheet without having to create individual .csv files.  We wrote ourselves a little helper function called getsheet() around the RODBC package.  Then we loaded all of the sample accounts into a data.frame called SimpleMWRRData. Writing the IRR function At this point, it was time to write the money weighted rate of return (MWRR) function itself.  The definition of MWRR is easily found on the internet or if you are old school you can look in an investment performance text book.  In the customer proof, we based our calculations off the ones defined in the The Handbook of Investment Performance: A User’s Guide by David Spaulding since this is the reference book used by the customer.  (One of the nice things we found during the course of this proof-of-concept is that by using R to write our IRR functions we could easily incorporate the specific variations and business rules of the customer into the calculation.) The key thing with calculating IRR is the need to solve a complex equation with a numerical approximation technique.  For IRR, you need to find the value of the rate of return (r) that sets the Net Present Value of all the flows in and out of the account to zero.  With R, we solve this by defining our NPV function: where bmv is the beginning market value, cf is a vector of cash flows, t is a vector of time (relative to the beginning), emv is the ending market value, and tend is the ending time. Since solving for r is a one-dimensional optimization problem, we decided to take advantage of R’s optimize method (http://stat.ethz.ch/R-manual/R-patched/library/stats/html/optimize.html). The optimize method can be used to find a minimum or maximum; to find the value of r where our npv function is closest to zero, we wrapped our npv function inside the abs function and asked optimize to find the minimum.  Here is an example of using optimize: where low and high are scalars that indicate the range to search for an answer.   To test this out, we need to set values for bmv, cf, t, emv, tend, low, and high.  We will set low and high to some reasonable defaults. For example, this account had a negative 2.2% money weighted rate of return. Enhancing and Packaging the IRR function With numerical approximation methods like optimize, sometimes you will not be able to find an answer with your initial set of inputs.  To account for this, our approach was to first try to find an answer for r within a narrow range, then if we did not find an answer, try calling optimize() again with a broader range.  See the R help page on optimize()  for more details about the search range and its algorithm. At this point, we can now write a simplified version of our MWRR function.  (Our real-world version is  more sophisticated in that it calculates rate of returns for 5 different time periods [since inception, last quarter, year-to-date, last year, year before last year] in a single invocation.  In our actual customer proof, we also defined time-weighted rate of return calculations.  The beauty of R is that it was very easy to add these enhancements and additional calculations to our IRR package.)To simplify code deployment, we then created a new package of our IRR functions and sample data.  For this blog post, we only need to include our SimpleMWRR function and our SimpleMWRRData sample data.  We created the shell of the package by calling: To turn this package skeleton into something usable, at a minimum you need to edit the SimpleMWRR.Rd and SimpleMWRRData.Rd files in the \man subdirectory.  In those files, you need to at least provide a value for the “title” section. Once that is done, you can change directory to the IRR directory and type at the command-line: The myIRR package for this blog post (which has both SimpleMWRR source and SimpleMWRRData sample data) is downloadable from here: myIRR package Testing the myIRR package Here is an example of testing our IRR function once it was converted to an installable package: Calculating IRR for All the Accounts So far, we have shown how to calculate IRR for a single account.  The real-world issue is how do you calculate IRR for all of the accounts?This is the kind of situation where we can leverage the “Split-Apply-Combine” approach (see http://www.cscs.umich.edu/~crshalizi/weblog/815.html).  Given that our sample data can fit in memory, one easy approach is to use R’s “by” function.  (Other approaches to Split-Apply-Combine such as plyr can also be used.  See http://4dpiecharts.com/2011/12/16/a-quick-primer-on-split-apply-combine-problems/). Here is an example showing the use of “by” to calculate the money weighted rate of return for each account in our sample data set.  Recap and Next Steps At this point, you’ve seen the power of R being used to calculate IRR.  There were several good things: R could easily work with the spreadsheets of sample data we were given R’s optimize() function provided a nice way to solve for IRR- it was both fast and allowed us to avoid having to code our own iterative approximation algorithm R was a convenient language to express the customer-specific variations, business-rules, and exceptions that often occur in real-world calculations- these could be easily added to our IRR functions The Split-Apply-Combine technique can be used to perform calculations of IRR for multiple accounts at once. However, there are several challenges yet to be conquered at this point in our story: The actual data that needs to be used lives in a database, not in a spreadsheet The actual data is much, much bigger- too big to fit into the normal R memory space and too big to want to move across the network The overall process needs to run fast- much faster than a single processor The actual data needs to be kept secured- another reason to not want to move it from the database and across the network And the process of calculating the IRR needs to be integrated together with other database ETL activities, so that IRR’s can be calculated as part of the data warehouse refresh processes In our next blog post in this series, we will show you how Oracle R Enterprise solved these challenges.

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  • I don't understand why algorithms are so special

    - by Jessica
    I'm a student of computer science trying to soak up as much information on the topic as I can during my free time. I keep returning to algorithms time and again in various formats (online course, book, web tutorial), but the concept fails to sustain my attention. I just don't understand: why are algorithms so special? I can tell you why fractals are awesome, why the golden ratio is awesome, why origami is awesome and scientific applications of all the above. Heck I even love Newton's laws and conical sections. But when it comes to algorithms, I'm just not astounded. They are not insightful in new ways about human cognition at all. I was expecting algorithms to be shattering preconceptions and mind-altering but time and time again they fail miserably. What am I doing wrong in my approach? Can someone tell me why algorithms are so awesome?

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  • Architectural and Design Challenges with SOA

    With all of the hype about service oriented architecture (SOA) primarily through the use of web services, not much has been said about potential issues of using SOA in the design of an application. I am personally a fan of SOA, but it is not the solution for every application. Proper evaluation should be done on all requirements and use cases prior to deciding to go down the SOA road. It is important to consider how your application/service will handle the following perils as it executes. Example Challenges of SOA Network Connectivity Issues Handling Connectivity Issues Longer Processing/Transaction Times How many of us have had issues visiting our favorite web sites from time to time? The same issue will occur when using service based architecture especially if it is implemented using web services. Forcing applications to access services via a network connection introduces a lot of new failure points to the application. Potential failure points include: DNS issues, network hardware issues, remote server issues, and the lack of physical network connections. When network connectivity issues do occur, how are the service clients are implemented is very important. Should the client wait and poll the service until it is accessible again? If so what is the maximum wait time or number of attempts it should retry. Due to the fact of services being distributed across a network automatically increase the responsiveness of client applications due to the fact that processing time must now also include time to send and receive messages from called services. This could add nanoseconds to minutes per each request based on network load and server usage of the service provider. If speed highly desirable quality attribute then I would consider creating components that are hosted where the client application is located. References: Rader, Dave. (2002). Overcoming Web Services Challenges with Smart Design: http://soa.sys-con.com/node/39458

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  • Poor Customer Service Example

    - by MightyZot
    Lately I have been frustrated by examples of poor customer service. At least one is worth writing about because I don’t think companies realize the effects of their service policies on loyal customers. Bad Customer Service Example #1 Recently, I received an offer in the mail from my cable company, suddenLink. The offer was for an updated TiVo for $12/mo. Normally I ignore offers like this one because I already have the service they’re offering and many times advertisers are offering alternatives to what is already an excellent product offering. I tend to exhibit a high level of loyalty to the products and brands that I use. In this case, we were looking to upgrade our TiVo and this deal is attractive for several reasons: I don’t want to pay a huge amount up-front for the device, so paying a monthly amount for the device is attractive to me. My entertainment is almost all on a single invoice. I’m no longer going to be billed by suddenLink and TiVo. TiVo is still involved, so I am still loyal to the brand I love. I have resisted moving to other DVRs and services for over a decade. I called suddenLink to order the new TiVo and was rewarded with great customer service. In fact, I can’t remember ever getting poor customer service from suddenLink. They are always there to answer my technical support questions and they are very responsive to outages. Then I called TiVo. First of all, I chose the option on the phone system to change or cancel my service, which was consequently met by an inordinate hold time. (I’m calling this time inordinate because I get through very quickly if I want to purchase something.) This is a trend that I’ve noticed with companies – if you want me to be loyal to you, it should be just as easy to cancel your service as it is to purchase it. Because, I should never be cancelling because I am unhappy. And, if you ever want my business again, or more importantly a reference, then you’d better make the exit door open just as easy as the enter door. After quite some time on hold, I talked to “Victor” who was very courteous. Victor canceled my service and then told me that I could keep my current TiVo and transfer recorded programs to it from the new TiVo.  Cool I said, but what about the cost?  He said there was no extra cost.  This was also attractive to me because I paid for my TiVo and it would be good to use it for something at least.  That was four months ago. This month I noticed that TiVo was still charging me for my original service. I was a little upset, but I decided to give them the benefit of the doubt. After all, I am a loyal TiVo customer and I have resisted moving to other solutions for over a decade. I’m sure they will do whatever it takes to keep my business, through TiVo or through suddenLink. After quite some time on hold, I was able to talk to a customer service representative, “Les”. I explained that I am a loyal TiVo customer, but I purchased this deal through my cable provider. I’m still with TiVo, I just wanted a single bill and to take advantage of the pay-over-time option. “Les” told me that he was very sorry to hear that I’m leaving TiVo, to which I responded again that I wasn’t leaving TiVo, I just want one invoice, and to take advantage of the pay-over-time. So, after explaining that I requested a termination of the non-suddenLink account (TiVo can see both of course), I was put on hold again for quite some time while my refund was “approved”.  “Les” said that he could see my cancellation request back in July. Note that it is now November, so they have billed me inappropriately four times. After quite some time, he came back on the line and told me that he was able to “get me most of my money back.” He got approval to refund 90 days. Even though I requested cancellation of one of my accounts, TiVo has that cancellation request on file and they admit overbilling me, I am going to get “most” of my money back. To top this experience off, when we were ready to hang up, “Les” told me that he was sorry to see me go and that he hoped I would come back to TiVo again. Again, I explained to “Les” that I have not left TiVo. I am just paying them through suddenLink. At that point, he went into a small dissertation about how this is a special arrangement they have with suddenLink and very few others. He made me feel like I was doing something wrong. Why should I feel that way? TiVo made the deal with suddenLink, not me, and the deal seemed like a good compromise for me to be able to get what I need. Here is what TiVo Customer Service accomplished on those two calls – I no longer feel like I need to be loyal to the TiVo brand or service. If I had been treated better on these two calls, I would still be recommending TiVo to my friends. They would still be getting revenue from a loyal customer, who paid the same rate for over a decade, and this article wouldn’t be here for you to read. Interesting… In my opinion, if you want brand loyalty, be loyal to your customers!

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  • How I Work: Staying Productive Whilst Traveling

    - by BuckWoody
    I travel a lot. Not like some folks that are gone every week, mind you, although in the last month I’ve been to: Cambridge, UK; Anchorage, AK; San Jose, CA; Copenhagen, DK, Boston, MA; and I’m currently en-route to Anaheim, CA.  While this many places in a month is a bit unusual for me, I would say I travel frequently. I’ve travelled most of my 28+ years in IT, and at one time was a consultant traveling weekly.   With that much time away from my primary work location, I have to find ways to stay productive. Some might say “just rest – take a nap!” – but I’m not able to do that. For one thing, I’m a very light sleeper and I’ve never slept on a plane - even a 30+ hour trip to New Zealand in Business Class - so that just isn’t option. I also am not always in the plane, of course. There’s the hotel, the taxi/bus/train, the airport and then all that over again when I arrive. Since my regular jobs have many demands, I have to get work done.   Note: No, I’m not always focused on work. I need downtime just like everyone else. Sometimes I just think, watch a movie or listen to tunes – and I give myself permission to do that anytime – sometimes the whole trip. I have too fewheartbeats left in life to only focus on work – it’s just not that important, and neither am I. Some of these tasks are letters to friends and family, or other personal things. What I’m talking about here is a plan, not some task list I have to follow. When I get to the location I’m traveling to, I always build in as much time as I can to ensure I enjoy those sights and the people I’m with. I would find traveling to be a waste if not for that.   The Unrealistic Expectation As I would evaluate the trip I was taking – say a 6-8 hour flight – I would expect to get 10-12 hours of work done. After all, there’s the time at the airport, the taxi and so on, and then of course the time in the air with all of the room, power, internet and everything else I needed to get my work done. I would pile up tasks at home, pack my bags, and head happily to the magical land of the TSA.   Right. On return from the trip, I had accomplished little, had more e-mails and other work that had piled up, and I was tired, hungry, and unorganized. This had to change. So, I decided to do three things: Segment my work Set realistic expectations Plan accordingly  Segmenting By Available Resources The first task was to decide what kind of work I could do in each location – if any. I found that I was dependent on a few things to get work done, such as power, the Internet, and a place to sit down. Before I fly, I take some time at home to get all of the work I’d like to accomplish while away segmented into these areas, and print that out on paper, which goes in my suit-coat pocket along with a mechanical pencil. I print my tickets, and I’m all set for the adventure ahead. Then I simply do each kind of work whenever I’m in that situation. No power There are certain times when I don’t have power available. But not only that, I might not even be able to use most of my electronics. So I now schedule as many phone calls as I can for the taxi/bus/train ride and the airports as I can. I have a paper notebook (Moleskine, of course) and a pencil and I print out any notes or numbers I need prior to the trip. Once I’m airborne or at the airport, I work on my laptop. I check and respond to e-mails, create slides, write code, do architecture, whatever I can.  If I can’t use any electronics, or once the power runs out, I schedule time for reading. I can read at the airport or anywhere, actually, even in-flight or any other transport. I “read with a pencil”, meaning I take a lot of notes, which I liketo put in OneNote, but since in most cases I don’t have power, I use the Moleskine to do that. Speaking of which, sometimes as I’m thinking I come up with new topics, ideas, blog posts, or things to teach in my classes. Once again I take out the notebook and write it down. All of these notes get a check-mark when I get back to the office and transfer the writing to OneNote. I’ve tried those “smart pens” and so on to automate this, but it just never works out. Pencil and paper are just fine. As I mentioned, sometime I just need to think. I’ll do nothing, and let my mind wander, thinking of nothing in particular, or some math problem or science question I’m interested in. My only issue with this is that I communicate tothink, and I don’t want to drive people crazy by being that guy that won’t shut up, so I think in a different way. Power, but no Internet or Phone If I have power but no Internet or phone, I focus on the laptop and the tablet as before, and I also recharge my other gadgets. Power, Internet, Phone and a Place to Work At first I thought that when I arrived at the hotel or event I could get the same amount of work done that I do at the office. Not so. There’s simply too many distractions, things you need, or other issues that allow this. Of course, Ican work on any device, read, think, write or whatever, but I am simply not as productive as I am in my home office. So I plan for about 25-50% as much work getting done in this environment as I think I could really do. I’ve done some measurements, and this holds out to be true almost every time. The key is that I re-set my expectations (and my co-worker’s expectations as well) that this is the case. I use the Out-Of-Office notices to let people know that I’m just not going to be 100% at this time – it’s hard for everyone, but it’s more honest and realistic, and I’d rather they know that – and that I realize that – than to let them think I’m totally available. Because I’m not – I’m traveling. I don’t tend to put too much detail, because after all I don’t necessarily want to let people know when I’m not home :) but I do think it’s important to let people that depend on my know that I’ll get back with them later. I hope this helps you think through your own methodology of staying productive when you travel. Or perhaps you just go offline, and don’t worry about any of this – good for you! That’s completely valid as well.   (Oh, and yes, I wrote this at 35K feet, on Alaska Airlines on a trip. :)  Practice what you preach, Buck.)

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  • DBA Best Practices - A Blog Series: Episode 1 - Backups

    - by Argenis
      This blog post is part of the DBA Best Practices series, on which various topics of concern for daily database operations are discussed. Your feedback and comments are very much welcome, so please drop by the comments section and be sure to leave your thoughts on the subject. Morning Coffee When I was a DBA, the first thing I did when I sat down at my desk at work was checking that all backups had completed successfully. It really was more of a ritual, since I had a dual system in place to check for backup completion: 1) the scheduled agent jobs to back up the databases were set to alert the NOC in failure, and 2) I had a script run from a central server every so often to check for any backup failures. Why the redundancy, you might ask. Well, for one I was once bitten by the fact that database mail doesn't work 100% of the time. Potential causes for failure include issues on the SMTP box that relays your server email, firewall problems, DNS issues, etc. And so to be sure that my backups completed fine, I needed to rely on a mechanism other than having the servers do the taking - I needed to interrogate the servers and ask each one if an issue had occurred. This is why I had a script run every so often. Some of you might have monitoring tools in place like Microsoft System Center Operations Manager (SCOM) or similar 3rd party products that would track all these things for you. But at that moment, we had no resort but to write our own Powershell scripts to do it. Now it goes without saying that if you don't have backups in place, you might as well find another career. Your most sacred job as a DBA is to protect the data from a disaster, and only properly safeguarded backups can offer you peace of mind here. "But, we have a cluster...we don't need backups" Sadly I've heard this line more than I would have liked to. You need to understand that a cluster is comprised of shared storage, and that is precisely your single point of failure. A cluster will protect you from an issue at the Operating System level, and also under an outage of any SQL-related service or dependent devices. But it will most definitely NOT protect you against corruption, nor will it protect you against somebody deleting data from a table - accidentally or otherwise. Backup, fine. How often do I take a backup? The answer to this is something you will hear frequently when working with databases: it depends. What does it depend on? For one, you need to understand how much data your business is willing to lose. This is what's called Recovery Point Objective, or RPO. If you don't know how much data your business is willing to lose, you need to have an honest and realistic conversation about data loss expectations with your customers, internal or external. From my experience, their first answer to the question "how much data loss can you withstand?" will be "zero". In that case, you will need to explain how zero data loss is very difficult and very costly to achieve, even in today's computing environments. Do you want to go ahead and take full backups of all your databases every hour, or even every day? Probably not, because of the impact that taking a full backup can have on a system. That's what differential and transaction log backups are for. Have I answered the question of how often to take a backup? No, and I did that on purpose. You need to think about how much time you have to recover from any event that requires you to restore your databases. This is what's called Recovery Time Objective. Again, if you go ask your customer how long of an outage they can withstand, at first you will get a completely unrealistic number - and that will be your starting point for discussing a solution that is cost effective. The point that I'm trying to get across is that you need to have a plan. This plan needs to be practiced, and tested. Like a football playbook, you need to rehearse the moves you'll perform when the time comes. How often is up to you, and the objective is that you feel better about yourself and the steps you need to follow when emergency strikes. A backup is nothing more than an untested restore Backups are files. Files are prone to corruption. Put those two together and realize how you feel about those backups sitting on that network drive. When was the last time you restored any of those? Restoring your backups on another box - that, by the way, doesn't have to match the specs of your production server - will give you two things: 1) peace of mind, because now you know that your backups are good and 2) a place to offload your consistency checks with DBCC CHECKDB or any of the other DBCC commands like CHECKTABLE or CHECKCATALOG. This is a great strategy for VLDBs that cannot withstand the additional load created by the consistency checks. If you choose to offload your consistency checks to another server though, be sure to run DBCC CHECKDB WITH PHYSICALONLY on the production server, and if you're using SQL Server 2008 R2 SP1 CU4 and above, be sure to enable traceflags 2562 and/or 2549, which will speed up the PHYSICALONLY checks further - you can read more about this enhancement here. Back to the "How Often" question for a second. If you have the disk, and the network latency, and the system resources to do so, why not backup the transaction log often? As in, every 5 minutes, or even less than that? There's not much downside to doing it, as you will have to clear the log with a backup sooner than later, lest you risk running out space on your tlog, or even your drive. The one drawback to this approach is that you will have more files to deal with at restore time, and processing each file will add a bit of extra time to the entire process. But it might be worth that time knowing that you minimized the amount of data lost. Again, test your plan to make sure that it matches your particular needs. Where to back up to? Network share? Locally? SAN volume? This is another topic where everybody has a favorite choice. So, I'll stick to mentioning what I like to do and what I consider to be the best practice in this regard. I like to backup to a SAN volume, i.e., a drive that actually lives in the SAN, and can be easily attached to another server in a pinch, saving you valuable time - you wouldn't need to restore files on the network (slow) or pull out drives out a dead server (been there, done that, it’s also slow!). The key is to have a copy of those backup files made quickly, and, if at all possible, to a remote target on a different datacenter - or even the cloud. There are plenty of solutions out there that can help you put such a solution together. That right there is the first step towards a practical Disaster Recovery plan. But there's much more to DR, and that's material for a different blog post in this series.

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  • Oracle Flashback Technology - Webcast 9th June 2010

    - by Alex Blyth
    Hi All Here are the details for webcast on Oracle Flashback Technologies on Wednesday (9th June 2010) beginning at 1.30pm (Sydney, Australia Time). The Oracle Database architecture leverages the unique technological advances in the area of database recovery due to human errors. Oracle Flashback Technology provides a set of new features to view and rewind data back and forth in time. The Flashback features offer the capability to query historical data, perform change analysis, and perform self-service repair to recover from logical corruptions while the database is online. With Oracle Flashback Technology, you can indeed undo the past! Oracle9i introduced Flashback Query to provide a simple, powerful and completely non-disruptive mechanism for recovering from human errors. It allows users to view the state of data at a point in time in the past without requiring any structural changes to the database. Oracle Database 10g extended the Flashback Technology to provide fast and easy recovery at the database, table, row, and transaction level. Flashback Technology revolutionizes recovery by operating just on the changed data. The time it takes to recover the error is now equal to the same amount of time it took to make the mistake. Oracle 10g Flashback Technologies includes Flashback Database, Flashback Table, Flashback Drop, Flashback Versions Query, and Flashback Transaction Query. Flashback technology can just as easily be utilized for non-repair purposes, such as historical auditing with Flashback Query and undoing test changes with Flashback Database. Oracle Database 11g introduces an innovative method to manage and query long-term historical data with Flashback Data Archive. This release also provides an easy, one-step transaction backout operation, with the new Flashback Transaction capability. Webcast is at http://strtc.oracle.com (IE6, 7 & 8 supported only)Conference ID for the webcast is 6690835Conference Key: flashbackEnrollment is required. Please click here to enroll.Please use your real name in the name field (just makes it easier for us to help you out if we can't answer your questions on the call) Audio details: NZ Toll Free - 0800 888 157 orAU Toll Free - 1800420354 (or +61 2 8064 0613)Meeting ID: 7914841Meeting Passcode: 09062010 Talk to you all Wednesday 9th June Alex

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  • Mobile Apps for Oracle E-Business Suite

    - by Carlos Chang
    Crosspost from the mobile apps blog.  TL;DR Oracle E-Business Suite is now building mobile apps with Oracle Mobile Application Framework (MAF). Believe it! Build iOS and Android apps with once code base and get it done! By Steven Chan (Oracle Development)  Many things have changed in the mobile space over the last few years. Here's an update on our strategy for mobile apps for the E-Business Suite. Mobile app strategy We're building our family of mobile apps for the E-Business Suite using Oracle Mobile Application Framework.  This framework allows us to write a single application that can be run on Apple iOS and Google Android platforms. Mobile apps for the E-Business Suite will share a common look-and-feel. The E-Business Suite is a suite of over 200 product modules spanning Financials, Supply Chain, Human Resources, and many other areas. Our mobile app strategy is to release standalone apps for specific product modules.  Our Oracle Timecards app, which allows users to create and submit timecards, is an example of a standalone app. Some common functions that span multiple product areas will have dedicated apps, too. An example of this is ourOracle Approvals app, which allows users to review and approve requests for expenses, requisitions, purchase orders, recruitment vacancies and offers, and more. You can read more about our Oracle Mobile Approvals app here: Now Available: Oracle Mobile Approvals for iOS Our goal is to support smaller screen (e.g. smartphones) as well as larger screens (e.g. tablets), with the smaller screen versions generally delivered first.  Where possible, we will deliver these as universal apps.  An example is our Oracle Mobile Field Service app, which allows field service technicians to remotely access customer, product, service request, and task-related information.  This app can run on a smartphone, while providing a richer experience for tablets. Deploying EBS mobile apps The mobile apps, themselves (i.e. client-side components) can be downloaded by end-users from the Apple iTunes today.  Android versions will be available from Google play. You can monitor this blog for Android-related updates. Where possible, our mobile apps should be deployable with a minimum of server-side changes.  These changes will generally involve a consolidated server-side patch for technology-stack components, and possibly a server-side patch for the functional product module. Updates to existing mobile apps may require new server-side components to enable all of the latest mobile functionality. All EBS product modules are certified for internal intranet deployments (i.e. used by employees within an organization's firewall).  Only a subset of EBS products such as iRecruitment are certified to be deployed externally (i.e. used by non-employees outside of an organization's firewall).  Today, many organizations running the E-Business Suite do not expose their EBS environment externally and all of the mobile apps that we're building are intended for internal employee use.  Recognizing this, our mobile apps are currently designed for users who are connected to the organization's intranet via VPN.  We expect that this may change in future updates to our mobile apps. Mobile apps and internationalization The initial releases of our mobile apps will be in English.  Later updates will include translations for all left-to-right languages supported by the E-Business Suite.  Right-to-left languages will not be translated. Customizing apps for enterprise deployments The current generation of mobile apps for Oracle E-Business Suite cannot be customized. We are evaluating options for limited customizations, including corporate branding with logos, corporate color schemes, and others. This is a potentially-complex area with many tricky implications for deployment and maintenance.  We would be interested in hearing your requirements for customizations in enterprise deployments.Prerequisites Apple iOS 7 and higher Android 4.1 (API level 16) and higher, with minimum CPU/memory configurations listed here EBS 12.1: EBS 12.1.3 Family Packs for the related product module EBS 12.2.3 References Oracle E-Business Suite Mobile Apps, Release 12.1 and 12.2 Documentation (Note 1641772.1) Oracle E-Business Suite Mobile Apps Administrator's Guide, Release 12.1 and 12.2 (Note 1642431.1) Follow @OracleMobile on Twitter Oracle Mobile Blog is here. 

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  • Making dummy applications while not involved in LIVE work [closed]

    - by Ratan Sharma
    I know this is subjective but I am looking for some real time helpful points/advice here, which will be helpful for some to get motivated. In our company so many people are on bench(not assigned with real time work) and they do not want to experiment things by their own. What would be a good motivation for them to keep their learning spirit? I personally feel that one can learn and give more effort in live client work than regular practicing things and making dummies. Am I right here or it is just my thinking only?

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  • How to use Pixel Bender (pbj) in ActionScript3 on large Vectors to make fast calculations?

    - by Arthur Wulf White
    Remember my old question: 2d game view camera zoom, rotation & offset using 'Filter' / 'Shader' processing? I figured I could use a Pixel Bender Shader to do the computation for any large group of elements in a game to save on processing time. At least it's a theory worth checking. I also read this question: Pass large array to pixel shader Which I'm guessing is about accomplishing the same thing in a different language. I read this tutorial: http://unitzeroone.com/blog/2009/03/18/flash-10-massive-amounts-of-3d-particles-with-alchemy-source-included/ I am attempting to do some tests. Here is some of the code: private const SIZE : int = Math.pow(10, 5); private var testVectorNum : Vector.<Number>; private function testShader():void { shader.data.ab.value = [1.0, 8.0]; shader.data.src.input = testVectorNum; shader.data.src.width = SIZE/400; shader.data.src.height = 100; shaderJob = new ShaderJob(shader, testVectorNum, SIZE / 4, 1); var time : int = getTimer(), i : int = 0; shaderJob.start(true); trace("TEST1 : ", getTimer() - time); } The problem is that I keep getting a error saying: [Fault] exception, information=Error: Error #1000: The system is out of memory. Update: I managed to partially workaround the problem by converting the vector into bitmapData: (Using this technique I still get a speed boost of 3x using Pixel Bender) private function testShader():void { shader.data.ab.value = [1.0, 8.0]; var time : int = getTimer(), i : int = 0; testBitmapData.setVector(testBitmapData.rect, testVectorInt); shader.data.src.input = testBitmapData; shaderJob = new ShaderJob(shader, testBitmapData); shaderJob.start(true); testVectorInt = testBitmapData.getVector(testBitmapData.rect); trace("TEST1 : ", getTimer() - time); }

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  • Software development is (mostly) a trade, and what to do about it

    - by Jeff
    (This is another cross-post from my personal blog. I don’t even remember when I first started to write it, but I feel like my opinion is well enough baked to share.) I've been sitting on this for a long time, particularly as my opinion has changed dramatically over the last few years. That I've encountered more crappy code than maintainable, quality code in my career as a software developer only reinforces what I'm about to say. Software development is just a trade for most, and not a huge academic endeavor. For those of you with computer science degrees readying your pitchforks and collecting your algorithm interview questions, let me explain. This is not an assault on your way of life, and if you've been around, you know I'm right about the quality problem. You also know the HR problem is very real, or we wouldn't be paying top dollar for mediocre developers and importing people from all over the world to fill the jobs we can't fill. I'm going to try and outline what I see as some of the problems, and hopefully offer my views on how to address them. The recruiting problem I think a lot of companies are doing it wrong. Over the years, I've had two kinds of interview experiences. The first, and right, kind of experience involves talking about real life achievements, followed by some variation on white boarding in pseudo-code, drafting some basic system architecture, or even sitting down at a comprooder and pecking out some basic code to tackle a real problem. I can honestly say that I've had a job offer for every interview like this, save for one, because the task was to debug something and they didn't like me asking where to look ("everyone else in the company died in a plane crash"). The other interview experience, the wrong one, involves the classic torture test designed to make the candidate feel stupid and do things they never have, and never will do in their job. First they will question you about obscure academic material you've never seen, or don't care to remember. Then they'll ask you to white board some ridiculous algorithm involving prime numbers or some kind of string manipulation no one would ever do. In fact, if you had to do something like this, you'd Google for a solution instead of waste time on a solved problem. Some will tell you that the academic gauntlet interview is useful to see how people respond to pressure, how they engage in complex logic, etc. That might be true, unless of course you have someone who brushed up on the solutions to the silly puzzles, and they're playing you. But here's the real reason why the second experience is wrong: You're evaluating for things that aren't the job. These might have been useful tactics when you had to hire people to write machine language or C++, but in a world dominated by managed code in C#, or Java, people aren't managing memory or trying to be smarter than the compilers. They're using well known design patterns and techniques to deliver software. More to the point, these puzzle gauntlets don't evaluate things that really matter. They don't get into code design, issues of loose coupling and testability, knowledge of the basics around HTTP, or anything else that relates to building supportable and maintainable software. The first situation, involving real life problems, gives you an immediate idea of how the candidate will work out. One of my favorite experiences as an interviewee was with a guy who literally brought his work from that day and asked me how to deal with his problem. I had to demonstrate how I would design a class, make sure the unit testing coverage was solid, etc. I worked at that company for two years. So stop looking for algorithm puzzle crunchers, because a guy who can crush a Fibonacci sequence might also be a guy who writes a class with 5,000 lines of untestable code. Fashion your interview process on ways to reveal a developer who can write supportable and maintainable code. I would even go so far as to let them use the Google. If they want to cut-and-paste code, pass on them, but if they're looking for context or straight class references, hire them, because they're going to be life-long learners. The contractor problem I doubt anyone has ever worked in a place where contractors weren't used. The use of contractors seems like an obvious way to control costs. You can hire someone for just as long as you need them and then let them go. You can even give them the work that no one else wants to do. In practice, most places I've worked have retained and budgeted for the contractor year-round, meaning that the $90+ per hour they're paying (of which half goes to the person) would have been better spent on a full-time person with a $100k salary and benefits. But it's not even the cost that is an issue. It's the quality of work delivered. The accountability of a contractor is totally transient. They only need to deliver for as long as you keep them around, and chances are they'll never again touch the code. There's no incentive for them to get things right, there's little incentive to understand your system or learn anything. At the risk of making an unfair generalization, craftsmanship doesn't matter to most contractors. The education problem I don't know what they teach in college CS courses. I've believed for most of my adult life that a college degree was an essential part of being successful. Of course I would hold that bias, since I did it, and have the paper to show for it in a box somewhere in the basement. My first clue that maybe this wasn't a fully qualified opinion comes from the fact that I double-majored in journalism and radio/TV, not computer science. Eventually I worked with people who skipped college entirely, many of them at Microsoft. Then I worked with people who had a masters degree who sucked at writing code, next to the high school diploma types that rock it every day. I still think there's a lot to be said for the social development of someone who has the on-campus experience, but for software developers, college might not matter. As I mentioned before, most of us are not writing compilers, and we never will. It's actually surprising to find how many people are self-taught in the art of software development, and that should reveal some interesting truths about how we learn. The first truth is that we learn largely out of necessity. There's something that we want to achieve, so we do what I call just-in-time learning to meet those goals. We acquire knowledge when we need it. So what about the gaps in our knowledge? That's where the most valuable education occurs, via our mentors. They're the people we work next to and the people who write blogs. They are critical to our professional development. They don't need to be an encyclopedia of jargon, but they understand the craft. Even at this stage of my career, I probably can't tell you what SOLID stands for, but you can bet that I practice the principles behind that acronym every day. That comes from experience, augmented by my peers. I'm hell bent on passing that experience to others. Process issues If you're a manager type and don't do much in the way of writing code these days (shame on you for not messing around at least), then your job is to isolate your tradespeople from nonsense, while bringing your business into the realm of modern software development. That doesn't mean you slap up a white board with sticky notes and start calling yourself agile, it means getting all of your stakeholders to understand that frequent delivery of quality software is the best way to deal with change and evolving expectations. It also means that you have to play technical overlord to make sure the education and quality issues are dealt with. That's why I make the crack about sticky notes, because without the right technique being practiced among your code monkeys, you're just a guy with sticky notes. You're asking your business to accept frequent and iterative delivery, now make sure that the folks writing the code can handle the same thing. This means unit testing, the right instrumentation, integration tests, automated builds and deployments... all of the stuff that makes it easy to see when change breaks stuff. The prognosis I strongly believe that education is the most important part of what we do. I'm encouraged by things like The Starter League, and it's the kind of thing I'd love to see more of. I would go as far as to say I'd love to start something like this internally at an existing company. Most of all though, I can't emphasize enough how important it is that we mentor each other and share our knowledge. If you have people on your staff who don't want to learn, fire them. Seriously, get rid of them. A few months working with someone really good, who understands the craftsmanship required to build supportable and maintainable code, will change that person forever and increase their value immeasurably.

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  • SQL Rally Relational Database Design Pre-Con Preview

    - by drsql
    On May 9, 2012, I will be presenting a pre-con session at the SQL Rally in Dallas, TX on relational database design. The fact is, database design is a topic that demands more than a simple one hour session to really do it right. So in my Relational Database Design Workshop, we will have seven times the amount of time in the typical session, giving us time to cover our topics in a bit more detail, look at a lot more designs/code, and even get some time to do some design as a group. Our topics will...(read more)

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  • Preventing pop-up dialogs when connecting an MTP device

    - by DrownedSensors
    I'm using Lubuntu 14.04 with a Samsung Galaxy S3 running Android 4.3. Each time I connect my phone via USB, I get the following dialog: Unable to open MTP device '[usb:002,023]' A few moments later, I get the "Removable medium is inserted" dialog, prompting me to open in File Manager. After that, the phone is connected and fully accessible. So MTP works. The problem is that I plug in my phone to charge every time I sit down, and unplug it every time I step away. Dismissing these two dialogs every time is a pain. I would think the "Removable medium" dialog is the easier candidate. How do I tell Ubuntu to take no action and stop prompting me? For the MTP error, all the discussion I can find is for people who can't get MTP working at all. For me, it's working, but only after throwing this initial error. I've verified that my device is present in /lib/udev/rules.d/69-libmtp.rules

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  • Date calculation algorithm

    - by Julian Cuevas
    I'm working on a project to schedule a machine shop, basically I've got everything covered BUT date calculations, I've got a method called schedule (working on PHP here): public function schedule($start_date, $duration_in_minutes) Now my problem is, currently I'm calculating end time manually because time calculations have the following rules: During weekdays, work with business hours (7:00 AM to 5:00 PM) Work on Saturdays from 7:00 AM to 2:00 PM Ignore holidays (in Colombia we have A LOT of holidays) I already have a lookup table for holidays, I also have a Java version of this algorithm that I wrote for a previous version of the project, but that one's also manual. Is there any way to calculate an end time from a start time given duration?, my problem is that I have to consider the above rules, I'm looking for a (maybe?) math based solution, however I currently don't have the mind to devise such a solution myself. I'll be happy to provide code samples if necessary.

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  • periodically overridding NTP for simulation purposes

    - by Gerard
    I have this situation: NTP is used to sync time on a set of Windows 7 and Server 2008 machines. Nothing out of the ordinary about this. periodically on this system, the time needs to be changed for testing/training purposes (it is a training simulation system that has a lot of time-dependent operations). My question: As NTP in general does not really like big time jumps or changes AFAIK, is there a standard way this could be set up to allow the clock to be changed at the root NTP server in the system and have it propagate through the system in a reasonable amount of time (a minute or two?) It is not acceptable to disable and/or restart all NTP client services to achieve this. Any ideas? It would be nice to do this without writing some kind of custom script to disable services and update clocks all over the place. Thanks in advance.

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  • Android Swipe In Unity 3D World with AR

    - by Christian
    I am working on an AR application using Unity3D and the Vuforia SDK for Android. The way the application works is a when the designated image(a frame marker in our case) is recognized by the camera, a 3D island is rendered at that spot. Currently I am able to detect when/which objects are touched on the model by raycasting. I also am able to successfully detect a swipe using this code: if (Input.touchCount > 0) { Touch touch = Input.touches[0]; switch (touch.phase) { case TouchPhase.Began: couldBeSwipe = true; startPos = touch.position; startTime = Time.time; break; case TouchPhase.Moved: if (Mathf.Abs(touch.position.y - startPos.y) > comfortZoneY) { couldBeSwipe = false; } //track points here for raycast if it is swipe break; case TouchPhase.Stationary: couldBeSwipe = false; break; case TouchPhase.Ended: float swipeTime = Time.time - startTime; float swipeDist = (touch.position - startPos).magnitude; if (couldBeSwipe && (swipeTime < maxSwipeTime) && (swipeDist > minSwipeDist)) { // It's a swiiiiiiiiiiiipe! float swipeDirection = Mathf.Sign(touch.position.y - startPos.y); // Do something here in reaction to the swipe. swipeCounter.IncrementCounter(); } break; } touchInfo.SetTouchInfo (Time.time-startTime,(touch.position-startPos).magnitude,Mathf.Abs (touch.position.y-startPos.y)); } Thanks to andeeeee for the logic. But I want to have some interaction in the 3D world based on the swipe on the screen. I.E. If the user swipes over unoccluded enemies, they die. My first thought was to track all the points in the moved TouchPhase, and then if it is a swipe raycast into all those points and kill any enemy that is hit. Is there a better way to do this? What is the best approach? Thanks for the help!

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  • apt-get works with --force-yes but cannot reproduce the issue on a fresh box

    - by deepak
    apt-get does not work the first time but works the second time i install ntp like: apt-get -q -y install ntp=1:4.2.6.p3+dfsg-1ubuntu3.1 It failed saying: WARNING: The following packages cannot be authenticated! libcap2 libopts25 ntp E: There are problems and -y was used without --force-yes Afterwards i ran, apt-key update and ran the same commad with --force-yes: apt-get -q -y --force-yes install ntp=1:4.2.6.p3+dfsg-1ubuntu3.1 Thereafter running apt-get purge and reinstalling ntp runs. "without" --force-yes apt-get purge libcap2 libopts25 ntp apt-get -q -y install ntp=1:4.2.6.p3+dfsg-1ubuntu3.1 Also i created a fresh VM and could not reproduce the issue. On a fresh VM, the same apt-get command runs the first time, without "--force-yes" Two questions, why does running apt-get work the second time and cannot reproduce the error ? full errors and sequential steps at, https://gist.github.com/3017966

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  • Solutions for software using many calls to a server

    - by Val
    I am developing software that uses many calls to a server. On a client side it's a Silverlight application. Almost every time a user clicks on a button in it, it sends 1-5 WCF calls to a server. There can be up to dozen or so users at a time. The server is a database server that serves data to a client. I am an intermediate level developer and am thinking about caching some data and syncing my changes from time to time. Are there any official solutions or technologies for it, like, patterns and such?

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  • DBA Best Practices - A Blog Series: Episode 1 - Backups

    - by Argenis
      This blog post is part of the DBA Best Practices series, on which various topics of concern for daily database operations are discussed. Your feedback and comments are very much welcome, so please drop by the comments section and be sure to leave your thoughts on the subject. Morning Coffee When I was a DBA, the first thing I did when I sat down at my desk at work was checking that all backups have completed successfully. It really was more of a ritual, since I had a dual system in place to check for backup completion: 1) the scheduled agent jobs to back up the databases were set to alert the NOC in failure, and 2) I had a script run from a central server every so often to check for any backup failures. Why the redundancy, you might ask. Well, for one I was once bitten by the fact that database mail doesn't work 100% of the time. Potential causes for failure include issues on the SMTP box that relays your server email, firewall problems, DNS issues, etc. And so to be sure that my backups completed fine, I needed to rely on a mechanism other than having the servers do the taking - I needed to interrogate the servers and ask each one if an issue had occurred. This is why I had a script run every so often. Some of you might have monitoring tools in place like Microsoft System Center Operations Manager (SCOM) or similar 3rd party products that would track all these things for you. But at that moment, we had no resort but to write our own Powershell scripts to do it. Now it goes without saying that if you don't have backups in place, you might as well find another career. Your most sacred job as a DBA is to protect the data from a disaster, and only properly safeguarded backups can offer you peace of mind here. "But, we have a cluster...we don't need backups" Sadly I've heard this line more than I would have liked to. You need to understand that a cluster is comprised of shared storage, and that is precisely your single point of failure. A cluster will protect you from an issue at the Operating System level, and also under an outage of any SQL-related service or dependent devices. But it will most definitely NOT protect you against corruption, nor will it protect you against somebody deleting data from a table - accidentally or otherwise. Backup, fine. How often do I take a backup? The answer to this is something you will hear frequently when working with databases: it depends. What does it depend on? For one, you need to understand how much data your business is willing to lose. This is what's called Recovery Point Objective, or RPO. If you don't know how much data your business is willing to lose, you need to have an honest and realistic conversation about data loss expectations with your customers, internal or external. From my experience, their first answer to the question "how much data loss can you withstand?" will be "zero". In that case, you will need to explain how zero data loss is very difficult and very costly to achieve, even in today's computing environments. Do you want to go ahead and take full backups of all your databases every hour, or even every day? Probably not, because of the impact that taking a full backup can have on a system. That's what differential and transaction log backups are for. Have I answered the question of how often to take a backup? No, and I did that on purpose. You need to think about how much time you have to recover from any event that requires you to restore your databases. This is what's called Recovery Time Objective. Again, if you go ask your customer how long of an outage they can withstand, at first you will get a completely unrealistic number - and that will be your starting point for discussing a solution that is cost effective. The point that I'm trying to get across is that you need to have a plan. This plan needs to be practiced, and tested. Like a football playbook, you need to rehearse the moves you'll perform when the time comes. How often is up to you, and the objective is that you feel better about yourself and the steps you need to follow when emergency strikes. A backup is nothing more than an untested restore Backups are files. Files are prone to corruption. Put those two together and realize how you feel about those backups sitting on that network drive. When was the last time you restored any of those? Restoring your backups on another box - that, by the way, doesn't have to match the specs of your production server - will give you two things: 1) peace of mind, because now you know that your backups are good and 2) a place to offload your consistency checks with DBCC CHECKDB or any of the other DBCC commands like CHECKTABLE or CHECKCATALOG. This is a great strategy for VLDBs that cannot withstand the additional load created by the consistency checks. If you choose to offload your consistency checks to another server though, be sure to run DBCC CHECKDB WITH PHYSICALONLY on the production server, and if you're using SQL Server 2008 R2 SP1 CU4 and above, be sure to enable traceflags 2562 and/or 2549, which will speed up the PHYSICALONLY checks further - you can read more about this enhancement here. Back to the "How Often" question for a second. If you have the disk, and the network latency, and the system resources to do so, why not backup the transaction log often? As in, every 5 minutes, or even less than that? There's not much downside to doing it, as you will have to clear the log with a backup sooner than later, lest you risk running out space on your tlog, or even your drive. The one drawback to this approach is that you will have more files to deal with at restore time, and processing each file will add a bit of extra time to the entire process. But it might be worth that time knowing that you minimized the amount of data lost. Again, test your plan to make sure that it matches your particular needs. Where to back up to? Network share? Locally? SAN volume? This is another topic where everybody has a favorite choice. So, I'll stick to mentioning what I like to do and what I consider to be the best practice in this regard. I like to backup to a SAN volume, i.e., a drive that actually lives in the SAN, and can be easily attached to another server in a pinch, saving you valuable time - you wouldn't need to restore files on the network (slow) or pull out drives out a dead server (been there, done that, it’s also slow!). The key is to have a copy of those backup files made quickly, and, if at all possible, to a remote target on a different datacenter - or even the cloud. There are plenty of solutions out there that can help you put such a solution together. That right there is the first step towards a practical Disaster Recovery plan. But there's much more to DR, and that's material for a different blog post in this series.

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  • Overwrite SOA expiry in a bind9 slave name server.

    - by Joachim Breitner
    I run a slave name server of a domain that I do not have full control over (i.e. changing the SOA is not possibly). The SOA specifies an expiry time of one week. For various reasons, I’d like to override that value on my specific slave server to something larger. Is there a way to do that? N.B: I know that for the refresh and retry fields, bind9 provides the options min-refresh-time, max-refresh-time, min-retry-time and max-retry-time to overrule the SOA, as mentioned in the documentation. For some reason this just does not inclucde expiry.

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  • Why do apt-get and wget fail on my server when ping is working?

    - by klox
    Yesterday my server still OK, but today after try to sudo apt-get update i got this error: update process. I try: sudo rm /var/lib/apt/lists/* -vf And got This.Then try update again, but it's not solving my problem then show May be still same error. I checked my internet connection try ping google.com, get result : PING google.com (74.125.235.40) 56(84) bytes of data. From 136.198.117.254: icmp_seq=1 Redirect Network(New nexthop: fw1.jvc-jein.co.id (136.198.117.6)) 64 bytes from sin01s05-in-f8.1e100.net (74.125.235.40): icmp_req=1 ttl=53 time=20.6 ms 64 bytes from sin01s05-in-f8.1e100.net (74.125.235.40): icmp_req=2 ttl=53 time=18.2 ms 64 bytes from sin01s05-in-f8.1e100.net (74.125.235.40): icmp_req=3 ttl=53 time=33.0 ms 64 bytes from sin01s05-in-f8.1e100.net (74.125.235.40): icmp_req=4 ttl=53 time=30.0 ms 64 bytes from sin01s05-in-f8.1e100.net (74.125.235.40): icmp_req=5 ttl=53 time=28.1 ms In some sites said that may be it caused by getdeb server is down. try to install: jeinqa@SVRQAR:~$ sudo apt-get install pastebinit Reading package lists... Error! E: Encountered a section with no Package: header E: Problem with MergeList /var/lib/apt/lists/security.ubuntu.com_ubuntu_dists_precise-security_restricted_binary-amd64_Packages E: The package lists or status file could not be parsed or opened. try : sudo ufw status verbose result : Status: inactive

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  • C#/.NET Little Wonders: Getting Caller Information

    - by James Michael Hare
    Originally posted on: http://geekswithblogs.net/BlackRabbitCoder/archive/2013/07/25/c.net-little-wonders-getting-caller-information.aspx Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. There are times when it is desirable to know who called the method or property you are currently executing.  Some applications of this could include logging libraries, or possibly even something more advanced that may server up different objects depending on who called the method. In the past, we mostly relied on the System.Diagnostics namespace and its classes such as StackTrace and StackFrame to see who our caller was, but now in C# 5, we can also get much of this data at compile-time. Determining the caller using the stack One of the ways of doing this is to examine the call stack.  The classes that allow you to examine the call stack have been around for a long time and can give you a very deep view of the calling chain all the way back to the beginning for the thread that has called you. You can get caller information by either instantiating the StackTrace class (which will give you the complete stack trace, much like you see when an exception is generated), or by using StackFrame which gets a single frame of the stack trace.  Both involve examining the call stack, which is a non-trivial task, so care should be done not to do this in a performance-intensive situation. For our simple example let's say we are going to recreate the wheel and construct our own logging framework.  Perhaps we wish to create a simple method Log which will log the string-ified form of an object and some information about the caller.  We could easily do this as follows: 1: static void Log(object message) 2: { 3: // frame 1, true for source info 4: StackFrame frame = new StackFrame(1, true); 5: var method = frame.GetMethod(); 6: var fileName = frame.GetFileName(); 7: var lineNumber = frame.GetFileLineNumber(); 8: 9: // we'll just use a simple Console write for now 10: Console.WriteLine("{0}({1}):{2} - {3}", 11: fileName, lineNumber, method.Name, message); 12: } So, what we are doing here is grabbing the 2nd stack frame (the 1st is our current method) using a 2nd argument of true to specify we want source information (if available) and then taking the information from the frame.  This works fine, and if we tested it out by calling from a file such as this: 1: // File c:\projects\test\CallerInfo\CallerInfo.cs 2:  3: public class CallerInfo 4: { 5: Log("Hello Logger!"); 6: } We'd see this: 1: c:\projects\test\CallerInfo\CallerInfo.cs(5):Main - Hello Logger! This works well, and in fact CallStack and StackFrame are still the best ways to examine deeper into the call stack.  But if you only want to get information on the caller of your method, there is another option… Determining the caller at compile-time In C# 5 (.NET 4.5) they added some attributes that can be supplied to optional parameters on a method to receive caller information.  These attributes can only be applied to methods with optional parameters with explicit defaults.  Then, as the compiler determines who is calling your method with these attributes, it will fill in the values at compile-time. These are the currently supported attributes available in the  System.Runtime.CompilerServices namespace": CallerFilePathAttribute – The path and name of the file that is calling your method. CallerLineNumberAttribute – The line number in the file where your method is being called. CallerMemberName – The member that is calling your method. So let’s take a look at how our Log method would look using these attributes instead: 1: static int Log(object message, 2: [CallerMemberName] string memberName = "", 3: [CallerFilePath] string fileName = "", 4: [CallerLineNumber] int lineNumber = 0) 5: { 6: // we'll just use a simple Console write for now 7: Console.WriteLine("{0}({1}):{2} - {3}", 8: fileName, lineNumber, memberName, message); 9: } Again, calling this from our sample Main would give us the same result: 1: c:\projects\test\CallerInfo\CallerInfo.cs(5):Main - Hello Logger! However, though this seems the same, there are a few key differences. First of all, there are only 3 supported attributes (at this time) that give you the file path, line number, and calling member.  Thus, it does not give you as rich of detail as a StackFrame (which can give you the calling type as well and deeper frames, for example).  Also, these are supported through optional parameters, which means we could call our new Log method like this: 1: // They're defaults, why not fill 'em in 2: Log("My message.", "Some member", "Some file", -13); In addition, since these attributes require optional parameters, they cannot be used in properties, only in methods. These caveats aside, they do let you get similar information inside of methods at a much greater speed!  How much greater?  Well lets crank through 1,000,000 iterations of each.  instead of logging to console, I’ll return the formatted string length of each.  Doing this, we get: 1: Time for 1,000,000 iterations with StackTrace: 5096 ms 2: Time for 1,000,000 iterations with Attributes: 196 ms So you see, using the attributes is much, much faster!  Nearly 25x faster in fact.  Summary There are a few ways to get caller information for a method.  The StackFrame allows you to get a comprehensive set of information spanning the whole call stack, but at a heavier cost.  On the other hand, the attributes allow you to quickly get at caller information baked in at compile-time, but to do so you need to create optional parameters in your methods to support it. Technorati Tags: Little Wonders,CSharp,C#,.NET,StackFrame,CallStack,CallerFilePathAttribute,CallerLineNumberAttribute,CallerMemberName

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  • Computer logout after closing the lid

    - by ejp1087
    I would like my computer to logout every time I close the lid. And by that I mean log out completely. Basically I want the startup applications to run every time I open the lid to my computer. Right now, it just locks the screen and comes right back when I type in my password. It would be really great if I can have it such that the startup applications run every time I open the lid. However, would logging out lose any unsaved files? Alternatively, do you know if there is a way to run a command every time I open the lid? Thanks!

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