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  • Paper on Linux memory access techniques sought

    - by James
    Over on stackoverflow someone posted a link to a paper written by a Linux kernel engineer about how to use computers and RAM. He started off by explaining how RAM works (right down to the flip-flops) and then went on to discuss performance problems associated with operations on matrices (column vs row accesses), offered solutions and then dealt with some stuff MMX instructions can do. Sorry it's a bit vague but I can't find it anywhere. I think the guy had a Scandinavian name, possibly Anders

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  • What issues tend to arise when working with HL7 messages?

    - by Ethel Evans
    I'm testing a product for health care businesses, and we're working with HL7 messages. I saw people groaning on another question about the issues with HL7 but not mentioning specifics. Can someone give me some ideas of what issues or classes of problems we should specifically be looking for? We are using some well-used libraries for the parsing. If specifics about these or what we're doing would be helpful please let me know in the comments and I'll add to the question if I can.

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  • BIEE Answer Parameter Passing

    - by Tim Dexter
    A little off BIP topic today but I spent some time researching how to pass parameters between Answer reports and knocked up a document for a client this morning and thought, what the heck someone might find it useful. If you have a source Answer request and you want to link to another Answer in another subject area and pass values to the target request, read this.

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  • Google I/O 2011: Life in App Engine Production

    Google I/O 2011: Life in App Engine Production Michael Handler, Alan Green App Engine runs your application at scale, so you can focus on features and not sysadminning. But SOMEONE has to run those computers for you! Come meet them, find out what keeps them up at night, and hear hair-raising Tales of the Unexpected. Plus, a demo of new monitoring options for your application, and a dash of HRD advocacy. From: GoogleDevelopers Views: 3393 37 ratings Time: 57:05 More in Science & Technology

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  • Bit-Twiddling in SQL

    - by Mike C
    Someone posted a question to the SQL Server forum the other day asking how to count runs of zero bits in an integer using SQL. Basically the poster wanted to know how to efficiently determine the longest contiguous string of zero-bits (known as a run of bits) in any given 32-bit integer. Here are a couple of examples to demonstrate the idea: Decimal = Binary = Zero Run 999,999,999 decimal = 00 111011 1 00 11010 11 00 1 00 1 11111111 binary = 2 contiguous zero bits 666,666,666 decimal = 00100111 10111100...(read more)

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  • Why does my MySQL remote-connection fail (VLAN)?

    - by Johannes Nielsen
    ubuntu-community! Again I have a problem with my special friend MySQL :D I have got two servers - a database-server and a web-server - who are connected via VLAN. Now I want the web-server to have remote access to the database-server's MySQL. So I created the user user in mysql.user. user's Host is xxx.yyy.zzz.9 which is the internal IP-address of the web-server. xxx.yyy.zzz.0 is the network. I also created user with Host % . As long as I use MySQL on the database-server logging in as user, everything works fine. But trying to log in as user from xxx.yyy.zzz.9 using mysql -h xxx.yyy.zzz.8 -u user -p (where xxx.yyy.zzz.8 is the database-server's internal IP), I get ERROR 2003 (HY000): Can't connect to MySQL server on 'xxx.yyy.zzz.8' (110) So I tried to activate Bind-Address in the my.cnf file. Well, if I use xxx.yyy.zzz.8, nothing changes. But if I try xxx.yyy.zzz.9 and try to restart MySQL, I get mysql stop/waiting start: Job failed to start I checked the log files and found - nothing. The database-server's MySQL doesn't even register, that the web-server tries to connect remotely. My idea is, that maybe I didn't configure the VLAN properley, even though I asked someone who actually knows such stuff and he told me, I did everything right. What I wrote into /etc/networking/interfaces is: #The VLAN auto eth1 iface eth1 inet static address xxx.yyy.zzz..8 netmask 255.255.255.0 network xxx.yyy.zzz.0 broadcast xxx.yyy.zzz.255 mtu 1500 ifconfig returns eth1 Link encap:Ethernet HWaddr xxxxxxxxxxxxxx inet addr:xxx.yyy.zzz.8 Bcast:xxx.yyy.zzz.255 Mask:255.255.255.0 inet6 addr: xxxxxxxxxxxxxxx/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:241146 errors:0 dropped:0 overruns:0 frame:0 TX packets:9765 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:17825995 (17.8 MB) TX bytes:566602 (566.6 KB) Memory:fb900000-fb920000 for the eth1, what is, what I configured. (This is for the database-server, the web-server looks similar). ethtool eth1 returns: Settings for eth1: Supported ports: [ TP ] Supported link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full 1000baseT/Full Supported pause frame use: No Supports auto-negotiation: Yes Advertised link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full 1000baseT/Full Advertised pause frame use: No Advertised auto-negotiation: Yes Speed: 100Mb/s Duplex: Full Port: Twisted Pair PHYAD: 1 Transceiver: internal Auto-negotiation: on MDI-X: Unknown Supports Wake-on: d Wake-on: d Current message level: 0x00000003 (3) drv probe Link detected: yes (This is for the database-server, the web-server looks similar). Actually I think, everything is right, but it still doesn't work. Is there someone with an idea? EDIT: I commented ou Bind-Address in my.cnf after it didn't work.

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  • Is hiring a "chief intern" a good idea?

    - by dukeofgaming
    I'm starting an internship program for our software department and I was wondering about creating a position ("chief intern", intern supervisor, or whatever one should call it) with the following responsibilities: Train interns Coach interns Manage projects and tasks for interns Supervise intern's work in terms of rhythm and quality Act as a liaison between the main team's needs and interns performance/aspirations Evaluate and facilitate intern's progress when they want to grab a higher-level domain-specific task (at this point, a main dev team member can do mentoring) Get freely involved in the main team's software development tasks so that he himself can grow, and have full mentorship from the main dev team. I'm thinking that an apprentice-level engineer (below Jr., or Jr.; but being a graduate and working full-time) can handle this for a while (he will be trained by the main dev team first), until one of two things happen: He/she decides to move on to the main dev team by recommending an appropriate replacement (or me finding another one as a new hire) Keep leading the interns while still being able to grow to Jr. Eng., Eng., Sr. Eng I know the notion of a "chief intern" is common within the medical world, but I don't really know about that in the software world (I was a freelancer for most of my university years). A side-intention to this is also that, if this ends up being a higher rotation position (organically) because the intern supervisor wants to join the main dev team, this could help interns that aspire this position emerge as leaders. My main intention for this, though, is removing distractions from the main team but without making the interns suffer the lack of attention, which could lead to boredom and little intern retention. Is this "chief intern" idea common (or good at least)?, are there any obvious risks to it that I might not be seeing? Edit: I have a draft plan for the kind of work the interns would be doing: Are R&D mini-projects a good activity for interns? Edit #2: My intention is not keeping them isolated, but having someone focus on giving attention to them when we cannot. Edit #3: I'm now convince it is a good idea, but I will take the organic approach to hiring someone in such position: do it myself until I cannot. This way I'll know better what to expect from a person I hire for this role in the future, as well as what works and what doesn't with interns.

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  • Comparing Standard Editions of SQL Server

    - by RickHeiges
    Recently, I've been speaking with customers about upgrading SQL Server. At times, some customers have a lot of Standard Edition SQL Server 2005 / 2008 / 2008R2 in their organization and they want to see the features they get when upgrading to SQL Server 2012. Last week, I sent out some tweets to the #sqlhelp hashtag to see if someone has already put together a document or blog post about comparing the Standard Editions. I was unable to discover anything out there that really focuses just on Standard...(read more)

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  • Updating Nvidia drivers 11.10 (nvidia 290.xxx.xxx)

    - by Jesse
    Hi I installed NVIDIA drivers using terminal. I added the newest repositories, to ensure getting the newest driver, once that was complete, I ran the following command: sudo apt-get install nvidia-current This started the download and successfully installed the (290.xx.xxx) version. The issue I have is when opening X-server application it still shows NVIDIA driver version 173.14.30. Can someone walk me through correcting this so it corresponds to the driver installed? Thanks

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  • Why We Write #6-An Interview with Kevin Kline

    - by drsql
    Wow, so far in this series, I have interviewed some very good friends, and some truly excellent writers (and usually both), but today, following on the heels of Jason Strate , we are going to hit someone whose name is synonymous with community, a person who really needs no introduction. According to Bing, Kevin Kline ( @kekline ) is the most important Kevin Kline on Twitter (though it clearly could be due to my typical searches, I am giving him the benefit of the doubt… here try it yourself: http://www.bing.com/search?q=kevin+kline+twitter...(read more)

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  • The Complexities to Creating Real Electronic Health Records

    <b>Linux Journal:</b> "But with all of this focus on streamlining and digitally electrifying health records, I began to wonder where did the Open Source community stand and where is its input? There is certainly a lot of money sitting out there for someone who wants to try to build the better mouse trap."

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  • Alerts for when Login Failures Strike

    When repeated SQL Server login failures occur, a DBA should investigate. It could just be someone repeatedly typing in the wrong password. Worst case is a virus attack flooding your network with connection requests. Receiving an e-mail while login failures are occurring allows DBAs to investigate and fix the issue as soon as possible. So how is DBA notified of login failures without flooding their inbox?

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  • “Advanced” talk to text program [on hold]

    - by Rocky
    So, I have asked this question on 3 sites before, without getting a good answer, basically what I need is: being able to put recorded voice in a file (preferrebly .txt) Automatic recording when saying a key-word Automatic stop of the recording after a bit of silence If you have any idea on how this is possible I would be very happy :) I tried dragon natural speaking before as someone said it would work (it did not) so unless you know how that is possible dont say it ;) (Not sure what site to ask this on)

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  • The Data Scientist

    - by BuckWoody
    A new term - well, perhaps not that new - has come up and I’m actually very excited about it. The term is Data Scientist, and since it’s new, it’s fairly undefined. I’ll explain what I think it means, and why I’m excited about it. In general, I’ve found the term deals at its most basic with analyzing data. Of course, we all do that, and the term itself in that definition is redundant. There is no science that I know of that does not work with analyzing lots of data. But the term seems to refer to more than the common practices of looking at data visually, putting it in a spreadsheet or report, or even using simple coding to examine data sets. The term Data Scientist (as far as I can make out this early in it’s use) is someone who has a strong understanding of data sources, relevance (statistical and otherwise) and processing methods as well as front-end displays of large sets of complicated data. Some - but not all - Business Intelligence professionals have these skills. In other cases, senior developers, database architects or others fill these needs, but in my experience, many lack the strong mathematical skills needed to make these choices properly. I’ve divided the knowledge base for someone that would wear this title into three large segments. It remains to be seen if a given Data Scientist would be responsible for knowing all these areas or would specialize. There are pretty high requirements on the math side, specifically in graduate-degree level statistics, but in my experience a company will only have a few of these folks, so they are expected to know quite a bit in each of these areas. Persistence The first area is finding, cleaning and storing the data. In some cases, no cleaning is done prior to storage - it’s just identified and the cleansing is done in a later step. This area is where the professional would be able to tell if a particular data set should be stored in a Relational Database Management System (RDBMS), across a set of key/value pair storage (NoSQL) or in a file system like HDFS (part of the Hadoop landscape) or other methods. Or do you examine the stream of data without storing it in another system at all? This is an important decision - it’s a foundation choice that deals not only with a lot of expense of purchasing systems or even using Cloud Computing (PaaS, SaaS or IaaS) to source it, but also the skillsets and other resources needed to care and feed the system for a long time. The Data Scientist sets something into motion that will probably outlast his or her career at a company or organization. Often these choices are made by senior developers, database administrators or architects in a company. But sometimes each of these has a certain bias towards making a decision one way or another. The Data Scientist would examine these choices in light of the data itself, starting perhaps even before the business requirements are created. The business may not even be aware of all the strategic and tactical data sources that they have access to. Processing Once the decision is made to store the data, the next set of decisions are based around how to process the data. An RDBMS scales well to a certain level, and provides a high degree of ACID compliance as well as offering a well-known set-based language to work with this data. In other cases, scale should be spread among multiple nodes (as in the case of Hadoop landscapes or NoSQL offerings) or even across a Cloud provider like Windows Azure Table Storage. In fact, in many cases - most of the ones I’m dealing with lately - the data should be split among multiple types of processing environments. This is a newer idea. Many data professionals simply pick a methodology (RDBMS with Star Schemas, NoSQL, etc.) and put all data there, regardless of its shape, processing needs and so on. A Data Scientist is familiar not only with the various processing methods, but how they work, so that they can choose the right one for a given need. This is a huge time commitment, hence the need for a dedicated title like this one. Presentation This is where the need for a Data Scientist is most often already being filled, sometimes with more or less success. The latest Business Intelligence systems are quite good at allowing you to create amazing graphics - but it’s the data behind the graphics that are the most important component of truly effective displays. This is where the mathematics requirement of the Data Scientist title is the most unforgiving. In fact, someone without a good foundation in statistics is not a good candidate for creating reports. Even a basic level of statistics can be dangerous. Anyone who works in analyzing data will tell you that there are multiple errors possible when data just seems right - and basic statistics bears out that you’re on the right track - that are only solvable when you understanding why the statistical formula works the way it does. And there are lots of ways of presenting data. Sometimes all you need is a “yes” or “no” answer that can only come after heavy analysis work. In that case, a simple e-mail might be all the reporting you need. In others, complex relationships and multiple components require a deep understanding of the various graphical methods of presenting data. Knowing which kind of chart, color, graphic or shape conveys a particular datum best is essential knowledge for the Data Scientist. Why I’m excited I love this area of study. I like math, stats, and computing technologies, but it goes beyond that. I love what data can do - how it can help an organization. I’ve been fortunate enough in my professional career these past two decades to work with lots of folks who perform this role at companies from aerospace to medical firms, from manufacturing to retail. Interestingly, the size of the company really isn’t germane here. I worked with one very small bio-tech (cryogenics) company that worked deeply with analysis of complex interrelated data. So  watch this space. No, I’m not leaving Azure or distributed computing or Microsoft. In fact, I think I’m perfectly situated to investigate this role further. We have a huge set of tools, from RDBMS to Hadoop to allow me to explore. And I’m happy to share what I learn along the way.

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  • Top SEO Tips to Let Your Site Top the Charts

    If you are someone looking for ways to popularize your site, you are in the right track. This article will teach you how to make your site literally come out on tops on the search lists of leading search engines. Using the top SEO tips discussed here, you can find your site zoom up the search lists in next to no time.

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  • Which design pattern to use when using ORM?

    - by RPK
    I am writing a small ASP.NET Web Forms application. In my solution explorer, I added various class library projects to define layers, viz: Model Repository Presentation WebUI Someone suggested me that this layered approach is not of much sense if I am using ORM tool like PetaPoco, which itself takes care of separation of data access layer. I want to use PetaPoco micro-ORM and want to know which design pattern is suitable with ORM tools. Do I still need several class library projects to separate the concerns?

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  • per pixel based collision detection.

    - by pengume
    I was wondering if anyone had any ideas on how to get per pixel collision detection for the android. I saw that the andEngine has great collision detection on rotation as well but couldn't see where the actual detection happened per pixel. Also noticed a couple solutions for java, could these be replicated for use with the Android SDK? Maybe someone here has a clean piece of code I could look at to help understand what is going on with per pixel detection and also why when rotating it is a different process.

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  • Programmatically Starting and Stopping FTP Sites in IIS 7 and IIS 8

    - by The Official Microsoft IIS Site
    I was recently contacted by someone who was trying to use Windows Management Instrumentation (WMI) code to stop and restart FTP websites by using code that he had written for IIS 6.0; his code was something similar to the following: Option Explicit On Error Resume Next Dim objWMIService, colItems, objItem ' Attach to the IIS service. Set objWMIService = GetObject( "winmgmts:\root\microsoftiisv2" ) ' Retrieve the collection of FTP sites. Set colItems = objWMIService.ExecQuery( "Select...(read more)

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  • Top 10 CV Tips - update

    - by simonsabin
    Three years ago I wrote a blog post about my top 10 CV tips. http://sqlblogcasts.com/blogs/simons/archive/2007/01/09/TOP-10-CV-Tips.aspx The world has changed slightly since then and one item I would add is that if you are active on the forums, stack overflow etc then put a link to your profile. This is a great way for recruiters to see some of your knowledge and importantly how you respond and interact with people. The latter is something that is crucial when employing someone but is very difficult...(read more)

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  • Website speed issue

    - by Jose David Garcia Llanos
    I've exhausted all my options. The website that I am developing had a load speed of 1.12 seconds and for some unknown reason it is now taking 2 seconds to connect then load. I've tried deactivating loads of plugins but is not the plugins or javascript or images. http://tools.pingdom.com/fpt/#!/ONC4QfFJt/n1bar.com I've tried re-configuring the cache and the .htacess file but still taking long for the first connection. Can someone help me find the problem...

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  • Mailing Lists Are Parties. Or They Should Be.

    <b>Luis Villa's Internet Home:</b> "I can&#8217;t go to bed because Mairin is right on the internet and so I want to (1) say she&#8217;s awesome and (2) add two cents on mailing lists and using the power of a web interface to make them better. Bear with me; maybe this is completely off-base (probably I should just stick to law), but it has been bouncing around in my head for years and maybe me writing it down will help the lightbulb go off for someone who can actually implement it :)"

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  • Local Search Engine Optimization - Why Use Local SEO?

    Local search engine optimization is the new optimization technique to help improve ones local efforts in your hometown or local areas a business does business. Local SEO is more useful for companies trying to gain new business within a smaller target range of 5-15 miles sometimes less sometimes more depending on the products or services one might provide to consumers. Local Search Engine Optimization and Normal Search Engine Optimization differs so hiring someone who specializes in local SEO is very important.

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  • Towards Database Continuous Delivery – What Next after Continuous Integration? A Checklist

    - by Ben Rees
    .dbd-banner p{ font-size:0.75em; padding:0 0 10px; margin:0 } .dbd-banner p span{ color:#675C6D; } .dbd-banner p:last-child{ padding:0; } @media ALL and (max-width:640px){ .dbd-banner{ background:#f0f0f0; padding:5px; color:#333; margin-top: 5px; } } -- Database delivery patterns & practices STAGE 4 AUTOMATED DEPLOYMENT If you’ve been fortunate enough to get to the stage where you’ve implemented some sort of continuous integration process for your database updates, then hopefully you’re seeing the benefits of that investment – constant feedback on changes your devs are making, advanced warning of data loss (prior to the production release on Saturday night!), a nice suite of automated tests to check business logic, so you know it’s going to work when it goes live, and so on. But what next? What can you do to improve your delivery process further, moving towards a full continuous delivery process for your database? In this article I describe some of the issues you might need to tackle on the next stage of this journey, and how to plan to overcome those obstacles before they appear. Our Database Delivery Learning Program consists of four stages, really three – source controlling a database, running continuous integration processes, then how to set up automated deployment (the middle stage is split in two – basic and advanced continuous integration, making four stages in total). If you’ve managed to work through the first three of these stages – source control, basic, then advanced CI, then you should have a solid change management process set up where, every time one of your team checks in a change to your database (whether schema or static reference data), this change gets fully tested automatically by your CI server. But this is only part of the story. Great, we know that our updates work, that the upgrade process works, that the upgrade isn’t going to wipe our 4Tb of production data with a single DROP TABLE. But – how do you get this (fully tested) release live? Continuous delivery means being always ready to release your software at any point in time. There’s a significant gap between your latest version being tested, and it being easily releasable. Just a quick note on terminology – there’s a nice piece here from Atlassian on the difference between continuous integration, continuous delivery and continuous deployment. This piece also gives a nice description of the benefits of continuous delivery. These benefits have been summed up by Jez Humble at Thoughtworks as: “Continuous delivery is a set of principles and practices to reduce the cost, time, and risk of delivering incremental changes to users” There’s another really useful piece here on Simple-Talk about the need for continuous delivery and how it applies to the database written by Phil Factor – specifically the extra needs and complexities of implementing a full CD solution for the database (compared to just implementing CD for, say, a web app). So, hopefully you’re convinced of moving on the the next stage! The next step after CI is to get some sort of automated deployment (or “release management”) process set up. But what should I do next? What do I need to plan and think about for getting my automated database deployment process set up? Can’t I just install one of the many release management tools available and hey presto, I’m ready! If only it were that simple. Below I list some of the areas that it’s worth spending a little time on, where a little planning and prep could go a long way. It’s also worth pointing out, that this should really be an evolving process. Depending on your starting point of course, it can be a long journey from your current setup to a full continuous delivery pipeline. If you’ve got a CI mechanism in place, you’re certainly a long way down that path. Nevertheless, we’d recommend evolving your process incrementally. Pages 157 and 129-141 of the book on Continuous Delivery (by Jez Humble and Dave Farley) have some great guidance on building up a pipeline incrementally: http://www.amazon.com/Continuous-Delivery-Deployment-Automation-Addison-Wesley/dp/0321601912 For now, in this post, we’ll look at the following areas for your checklist: You and Your Team Environments The Deployment Process Rollback and Recovery Development Practices You and Your Team It’s a cliché in the DevOps community that “It’s not all about processes and tools, really it’s all about a culture”. As stated in this DevOps report from Puppet Labs: “DevOps processes and tooling contribute to high performance, but these practices alone aren’t enough to achieve organizational success. The most common barriers to DevOps adoption are cultural: lack of manager or team buy-in, or the value of DevOps isn’t understood outside of a specific group”. Like most clichés, there’s truth in there – if you want to set up a database continuous delivery process, you need to get your boss, your department, your company (if relevant) onside. Why? Because it’s an investment with the benefits coming way down the line. But the benefits are huge – for HP, in the book A Practical Approach to Large-Scale Agile Development: How HP Transformed LaserJet FutureSmart Firmware, these are summarized as: -2008 to present: overall development costs reduced by 40% -Number of programs under development increased by 140% -Development costs per program down 78% -Firmware resources now driving innovation increased by a factor of 8 (from 5% working on new features to 40% But what does this mean? It means that, when moving to the next stage, to make that extra investment in automating your deployment process, it helps a lot if everyone is convinced that this is a good thing. That they understand the benefits of automated deployment and are willing to make the effort to transform to a new way of working. Incidentally, if you’re ever struggling to convince someone of the value I’d strongly recommend just buying them a copy of this book – a great read, and a very practical guide to how it can really work at a large org. I’ve spoken to many customers who have implemented database CI who describe their deployment process as “The point where automation breaks down. Up to that point, the CI process runs, untouched by human hand, but as soon as that’s finished we revert to manual.” This deployment process can involve, for example, a DBA manually comparing an environment (say, QA) to production, creating the upgrade scripts, reading through them, checking them against an Excel document emailed to him/her the night before, turning to page 29 in his/her notebook to double-check how replication is switched off and on for deployments, and so on and so on. Painful, error-prone and lengthy. But the point is, if this is something like your deployment process, telling your DBA “We’re changing everything you do and your toolset next week, to automate most of your role – that’s okay isn’t it?” isn’t likely to go down well. There’s some work here to bring him/her onside – to explain what you’re doing, why there will still be control of the deployment process and so on. Or of course, if you’re the DBA looking after this process, you have to do a similar job in reverse. You may have researched and worked out how you’d like to change your methodology to start automating your painful release process, but do the dev team know this? What if they have to start producing different artifacts for you? Will they be happy with this? Worth talking to them, to find out. As well as talking to your DBA/dev team, the other group to get involved before implementation is your manager. And possibly your manager’s manager too. As mentioned, unless there’s buy-in “from the top”, you’re going to hit problems when the implementation starts to get rocky (and what tool/process implementations don’t get rocky?!). You need to have support from someone senior in your organisation – someone you can turn to when you need help with a delayed implementation, lack of resources or lack of progress. Actions: Get your DBA involved (or whoever looks after live deployments) and discuss what you’re planning to do or, if you’re the DBA yourself, get the dev team up-to-speed with your plans, Get your boss involved too and make sure he/she is bought in to the investment. Environments Where are you going to deploy to? And really this question is – what environments do you want set up for your deployment pipeline? Assume everyone has “Production”, but do you have a QA environment? Dedicated development environments for each dev? Proper pre-production? I’ve seen every setup under the sun, and there is often a big difference between “What we want, to do continuous delivery properly” and “What we’re currently stuck with”. Some of these differences are: What we want What we’ve got Each developer with their own dedicated database environment A single shared “development” environment, used by everyone at once An Integration box used to test the integration of all check-ins via the CI process, along with a full suite of unit-tests running on that machine In fact if you have a CI process running, you’re likely to have some sort of integration server running (even if you don’t call it that!). Whether you have a full suite of unit tests running is a different question… Separate QA environment used explicitly for manual testing prior to release “We just test on the dev environments, or maybe pre-production” A proper pre-production (or “staging”) box that matches production as closely as possible Hopefully a pre-production box of some sort. But does it match production closely!? A production environment reproducible from source control A production box which has drifted significantly from anything in source control The big question is – how much time and effort are you going to invest in fixing these issues? In reality this just involves figuring out which new databases you’re going to create and where they’ll be hosted – VMs? Cloud-based? What about size/data issues – what data are you going to include on dev environments? Does it need to be masked to protect access to production data? And often the amount of work here really depends on whether you’re working on a new, greenfield project, or trying to update an existing, brownfield application. There’s a world if difference between starting from scratch with 4 or 5 clean environments (reproducible from source control of course!), and trying to re-purpose and tweak a set of existing databases, with all of their surrounding processes and quirks. But for a proper release management process, ideally you have: Dedicated development databases, An Integration server used for testing continuous integration and running unit tests. [NB: This is the point at which deployments are automatic, without human intervention. Each deployment after this point is a one-click (but human) action], QA – QA engineers use a one-click deployment process to automatically* deploy chosen releases to QA for testing, Pre-production. The environment you use to test the production release process, Production. * A note on the use of the word “automatic” – when carrying out automated deployments this does not mean that the deployment is happening without human intervention (i.e. that something is just deploying over and over again). It means that the process of carrying out the deployment is automatic in that it’s not a person manually running through a checklist or set of actions. The deployment still requires a single-click from a user. Actions: Get your environments set up and ready, Set access permissions appropriately, Make sure everyone understands what the environments will be used for (it’s not a “free-for-all” with all environments to be accessed, played with and changed by development). The Deployment Process As described earlier, most existing database deployment processes are pretty manual. The following is a description of a process we hear very often when we ask customers “How do your database changes get live? How does your manual process work?” Check pre-production matches production (use a schema compare tool, like SQL Compare). Sometimes done by taking a backup from production and restoring in to pre-prod, Again, use a schema compare tool to find the differences between the latest version of the database ready to go live (i.e. what the team have been developing). This generates a script, User (generally, the DBA), reviews the script. This often involves manually checking updates against a spreadsheet or similar, Run the script on pre-production, and check there are no errors (i.e. it upgrades pre-production to what you hoped), If all working, run the script on production.* * this assumes there’s no problem with production drifting away from pre-production in the interim time period (i.e. someone has hacked something in to the production box without going through the proper change management process). This difference could undermine the validity of your pre-production deployment test. Red Gate is currently working on a free tool to detect this problem – sign up here at www.sqllighthouse.com, if you’re interested in testing early versions. There are several variations on this process – some better, some much worse! How do you automate this? In particular, step 3 – surely you can’t automate a DBA checking through a script, that everything is in order!? The key point here is to plan what you want in your new deployment process. There are so many options. At one extreme, pure continuous deployment – whenever a dev checks something in to source control, the CI process runs (including extensive and thorough testing!), before the deployment process keys in and automatically deploys that change to the live box. Not for the faint hearted – and really not something we recommend. At the other extreme, you might be more comfortable with a semi-automated process – the pre-production/production matching process is automated (with an error thrown if these environments don’t match), followed by a manual intervention, allowing for script approval by the DBA. One he/she clicks “Okay, I’m happy for that to go live”, the latter stages automatically take the script through to live. And anything in between of course – and other variations. But we’d strongly recommended sitting down with a whiteboard and your team, and spending a couple of hours mapping out “What do we do now?”, “What do we actually want?”, “What will satisfy our needs for continuous delivery, but still maintaining some sort of continuous control over the process?” NB: Most of what we’re discussing here is about production deployments. It’s important to note that you will also need to map out a deployment process for earlier environments (for example QA). However, these are likely to be less onerous, and many customers opt for a much more automated process for these boxes. Actions: Sit down with your team and a whiteboard, and draw out the answers to the questions above for your production deployments – “What do we do now?”, “What do we actually want?”, “What will satisfy our needs for continuous delivery, but still maintaining some sort of continuous control over the process?” Repeat for earlier environments (QA and so on). Rollback and Recovery If only every deployment went according to plan! Unfortunately they don’t – and when things go wrong, you need a rollback or recovery plan for what you’re going to do in that situation. Once you move in to a more automated database deployment process, you’re far more likely to be deploying more frequently than before. No longer once every 6 months, maybe now once per week, or even daily. Hence the need for a quick rollback or recovery process becomes paramount, and should be planned for. NB: These are mainly scenarios for handling rollbacks after the transaction has been committed. If a failure is detected during the transaction, the whole transaction can just be rolled back, no problem. There are various options, which we’ll explore in subsequent articles, things like: Immediately restore from backup, Have a pre-tested rollback script (remembering that really this is a “roll-forward” script – there’s not really such a thing as a rollback script for a database!) Have fallback environments – for example, using a blue-green deployment pattern. Different options have pros and cons – some are easier to set up, some require more investment in infrastructure; and of course some work better than others (the key issue with using backups, is loss of the interim transaction data that has been added between the failed deployment and the restore). The best mechanism will be primarily dependent on how your application works and how much you need a cast-iron failsafe mechanism. Actions: Work out an appropriate rollback strategy based on how your application and business works, your appetite for investment and requirements for a completely failsafe process. Development Practices This is perhaps the more difficult area for people to tackle. The process by which you can deploy database updates is actually intrinsically linked with the patterns and practices used to develop that database and linked application. So you need to decide whether you want to implement some changes to the way your developers actually develop the database (particularly schema changes) to make the deployment process easier. A good example is the pattern “Branch by abstraction”. Explained nicely here, by Martin Fowler, this is a process that can be used to make significant database changes (e.g. splitting a table) in a step-wise manner so that you can always roll back, without data loss – by making incremental updates to the database backward compatible. Slides 103-108 of the following slidedeck, from Niek Bartholomeus explain the process: https://speakerdeck.com/niekbartho/orchestration-in-meatspace As these slides show, by making a significant schema change in multiple steps – where each step can be rolled back without any loss of new data – this affords the release team the opportunity to have zero-downtime deployments with considerably less stress (because if an increment goes wrong, they can roll back easily). There are plenty more great patterns that can be implemented – the book Refactoring Databases, by Scott Ambler and Pramod Sadalage is a great read, if this is a direction you want to go in: http://www.amazon.com/Refactoring-Databases-Evolutionary-paperback-Addison-Wesley/dp/0321774515 But the question is – how much of this investment are you willing to make? How often are you making significant schema changes that would require these best practices? Again, there’s a difference here between migrating old projects and starting afresh – with the latter it’s much easier to instigate best practice from the start. Actions: For your business, work out how far down the path you want to go, amending your database development patterns to “best practice”. It’s a trade-off between implementing quality processes, and the necessity to do so (depending on how often you make complex changes). Socialise these changes with your development group. No-one likes having “best practice” changes imposed on them, so good to introduce these ideas and the rationale behind them early.   Summary The next stages of implementing a continuous delivery pipeline for your database changes (once you have CI up and running) require a little pre-planning, if you want to get the most out of the work, and for the implementation to go smoothly. We’ve covered some of the checklist of areas to consider – mainly in the areas of “Getting the team ready for the changes that are coming” and “Planning our your pipeline, environments, patterns and practices for development”, though there will be more detail, depending on where you’re coming from – and where you want to get to. This article is part of our database delivery patterns & practices series on Simple Talk. Find more articles for version control, automated testing, continuous integration & deployment.

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  • When do you call yourself a programmer

    - by benhowdle89
    "A programmer, computer programmer or coder is someone who writes computer software" from Wikipedia If you do frontend development using jQuery/CSS/HTML do you call yourself a programmer? If you develop PHP applications that deal with databases, do you call yourself a programmer? Are you only a programmer if you write applications for desktops and mobiles? Is the web a place where the line between developer and programmer stops?

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