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  • Strange C++ performance difference?

    - by STingRaySC
    I just stumbled upon a change that seems to have counterintuitive performance ramifications. Can anyone provide a possible explanation for this behavior? Original code: for (int i = 0; i < ct; ++i) { // do some stuff... int iFreq = getFreq(i); double dFreq = iFreq; if (iFreq != 0) { // do some stuff with iFreq... // do some calculations with dFreq... } } While cleaning up this code during a "performance pass," I decided to move the definition of dFreq inside the if block, as it was only used inside the if. There are several calculations involving dFreq so I didn't eliminate it entirely as it does save the cost of multiple run-time conversions from int to double. I expected no performance difference, or if any at all, a negligible improvement. However, the perfomance decreased by nearly 10%. I have measured this many times, and this is indeed the only change I've made. The code snippet shown above executes inside a couple other loops. I get very consistent timings across runs and can definitely confirm that the change I'm describing decreases performance by ~10%. I would expect performance to increase because the int to double conversion would only occur when iFreq != 0. Chnaged code: for (int i = 0; i < ct; ++i) { // do some stuff... int iFreq = getFreq(i); if (iFreq != 0) { // do some stuff with iFreq... double dFreq = iFreq; // do some stuff with dFreq... } } Can anyone explain this? I am using VC++ 9.0 with /O2. I just want to understand what I'm not accounting for here.

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  • Why Software Sucks...and What You Can Do About It – book review

    - by DigiMortal
        How do our users see the products we are writing for them and how happy they are with our work? Are they able to get their work done without fighting with cool features and crashes or are they just switching off resistance part of their brain to survive our software? Yeah, the overall picture of software usability landscape is not very nice. Okay, it is not even nice. But, fortunately, Why Software Sucks...and What You Can Do About It by David S. Platt explains everything. Why Software Sucks… is book for software users but I consider it as a-must reading also for developers and specially for their managers whose politics often kills all usability topics as soon as they may appear. For managers usability is soft topic that can be manipulated the way it is best in current state of project. Although developers are not UI designers and usability experts they are still very often forced to deal with these topics and this is how usability problems start (of course, also designers are able to produce designs that are stupid and too hard to use for users, but this blog here is about development). I found this book to be very interesting and funny reading. It is not humor book but it explains you all so you remember later very well what you just read. It took me about three evenings to go through this book and I am still enjoying what I found and how author explains our weird young working field to end users. I suggest this book to all developers – while you are demanding your management to hire or outsource usability expert you are at least causing less pain to end users. So, go and buy this book, just like I did. And… they thanks to mr. Platt :) There is one book more I suggest you to read if you are interested in usability - Don't Make Me Think: A Common Sense Approach to Web Usability, 2nd Edition by Steve Krug. Editorial review from Amazon Today’s software sucks. There’s no other good way to say it. It’s unsafe, allowing criminal programs to creep through the Internet wires into our very bedrooms. It’s unreliable, crashing when we need it most, wiping out hours or days of work with no way to get it back. And it’s hard to use, requiring large amounts of head-banging to figure out the simplest operations. It’s no secret that software sucks. You know that from personal experience, whether you use computers for work or personal tasks. In this book, programming insider David Platt explains why that’s the case and, more importantly, why it doesn’t have to be that way. And he explains it in plain, jargon-free English that’s a joy to read, using real-world examples with which you’re already familiar. In the end, he suggests what you, as a typical user, without a technical background, can do about this sad state of our software—how you, as an informed consumer, don’t have to take the abuse that bad software dishes out. As you might expect from the book’s title, Dave’s expose is laced with humor—sometimes outrageous, but always dead on. You’ll laugh out loud as you recall incidents with your own software that made you cry. You’ll slap your thigh with the same hand that so often pounded your computer desk and wished it was a bad programmer’s face. But Dave hasn’t written this book just for laughs. He’s written it to give long-overdue voice to your own discovery—that software does, indeed, suck, but it shouldn’t. Table of contents Acknowledgments xiii Introduction Chapter 1: Who’re You Calling a Dummy? Where We Came From Why It Still Sucks Today Control versus Ease of Use I Don’t Care How Your Program Works A Bad Feature and a Good One Stopping the Proceedings with Idiocy Testing on Live Animals Where We Are and What You Can Do Chapter 2: Tangled in the Web Where We Came From How It Works Why It Still Sucks Today Client-Centered Design versus Server-Centered Design Where’s My Eye Opener? It’s Obvious—Not! Splash, Flash, and Animation Testing on Live Animals What You Can Do about It Chapter 3: Keep Me Safe The Way It Was Why It Sucks Today What Programmers Need to Know, but Don’t A Human Operation Budgeting for Hassles Users Are Lazy Social Engineering Last Word on Security What You Can Do Chapter 4: Who the Heck Are You? Where We Came From Why It Still Sucks Today Incompatible Requirements OK, So Now What? Chapter 5: Who’re You Looking At? Yes, They Know You Why It Sucks More Than Ever Today Users Don’t Know Where the Risks Are What They Know First Milk You with Cookies? Privacy Policy Nonsense Covering Your Tracks The Google Conundrum Solution Chapter 6: Ten Thousand Geeks, Crazed on Jolt Cola See Them in Their Native Habitat All These Geeks Who Speaks, and When, and about What Selling It The Next Generation of Geeks—Passing It On Chapter 7: Who Are These Crazy Bastards Anyway? Homo Logicus Testosterone Poisoning Control and Contentment Making Models Geeks and Jocks Jargon Brains and Constraints Seven Habits of Geeks Chapter 8: Microsoft: Can’t Live With ’Em and Can’t Live Without ’Em They Run the World Me and Them Where We Came From Why It Sucks Today Damned if You Do, Damned if You Don’t We Love to Hate Them Plus ça Change Growing-Up Pains What You Can Do about It The Last Word Chapter 9: Doing Something About It 1. Buy 2. Tell 3. Ridicule 4. Trust 5. Organize Epilogue About the Author

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  • SQL SERVER – Example of Performance Tuning for Advanced Users with DB Optimizer

    - by Pinal Dave
    Performance tuning is such a subject that everyone wants to master it. In beginning everybody is at a novice level and spend lots of time learning how to master the art of performance tuning. However, as we progress further the tuning of the system keeps on getting very difficult. I have understood in my early career there should be no need of ego in the technology field. There are always better solutions and better ideas out there and we should not resist them. Instead of resisting the change and new wave I personally adopt it. Here is a similar example, as I personally progress to the master level of performance tuning, I face that it is getting harder to come up with optimal solutions. In such scenarios I rely on various tools to teach me how I can do things better. Once I learn about tools, I am often able to come up with better solutions when I face the similar situation next time. A few days ago I had received a query where the user wanted to tune it further to get the maximum out of the performance. I have re-written the similar query with the help of AdventureWorks sample database. SELECT * FROM HumanResources.Employee e INNER JOIN HumanResources.EmployeeDepartmentHistory edh ON e.BusinessEntityID = edh.BusinessEntityID INNER JOIN HumanResources.Shift s ON edh.ShiftID = s.ShiftID; User had similar query to above query was used in very critical report and wanted to get best out of the query. When I looked at the query – here were my initial thoughts Use only column in the select statements as much as you want in the application Let us look at the query pattern and data workload and find out the optimal index for it Before I give further solutions I was told by the user that they need all the columns from all the tables and creating index was not allowed in their system. He can only re-write queries or use hints to further tune this query. Now I was in the constraint box – I believe * was not a great idea but if they wanted all the columns, I believe we can’t do much besides using *. Additionally, if I cannot create a further index, I must come up with some creative way to write this query. I personally do not like to use hints in my application but there are cases when hints work out magically and gives optimal solutions. Finally, I decided to use Embarcadero’s DB Optimizer. It is a fantastic tool and very helpful when it is about performance tuning. I have previously explained how it works over here. First open DBOptimizer and open Tuning Job from File >> New >> Tuning Job. Once you open DBOptimizer Tuning Job follow the various steps indicates in the following diagram. Essentially we will take our original script and will paste that into Step 1: New SQL Text and right after that we will enable Step 2 for Generating Various cases, Step 3 for Detailed Analysis and Step 4 for Executing each generated case. Finally we will click on Analysis in Step 5 which will generate the report detailed analysis in the result pan. The detailed pan looks like. It generates various cases of T-SQL based on the original query. It applies various hints and available hints to the query and generate various execution plans of the query and displays them in the resultant. You can clearly notice that original query had a cost of 0.0841 and logical reads about 607 pages. Whereas various options which are just following it has different execution cost as well logical read. There are few cases where we have higher logical read and there are few cases where as we have very low logical read. If we pay attention the very next row to original query have Merge_Join_Query in description and have lowest execution cost value of 0.044 and have lowest Logical Reads of 29. This row contains the query which is the most optimal re-write of the original query. Let us double click over it. Here is the query: SELECT * FROM HumanResources.Employee e INNER JOIN HumanResources.EmployeeDepartmentHistory edh ON e.BusinessEntityID = edh.BusinessEntityID INNER JOIN HumanResources.Shift s ON edh.ShiftID = s.ShiftID OPTION (MERGE JOIN) If you notice above query have additional hint of Merge Join. With the help of this Merge Join query hint this query is now performing much better than before. The entire process takes less than 60 seconds. Please note that it the join hint Merge Join was optimal for this query but it is not necessary that the same hint will be helpful in all the queries. Additionally, if the workload or data pattern changes the query hint of merge join may be no more optimal join. In that case, we will have to redo the entire exercise once again. This is the reason I do not like to use hints in my queries and I discourage all of my users to use the same. However, if you look at this example, this is a great case where hints are optimizing the performance of the query. It is humanly not possible to test out various query hints and index options with the query to figure out which is the most optimal solution. Sometimes, we need to depend on the efficiency tools like DB Optimizer to guide us the way and select the best option from the suggestion provided. Let me know what you think of this article as well your experience with DB Optimizer. Please leave a comment. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Joins, SQL Optimization, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • Is there an equivalent to the Max OS X software Hazel that runs on Ubuntu?

    - by Stuart Woodward
    Is there an equivalent to the Max OS X software Hazel that runs on Ubuntu? "Hazel watches whatever folders you tell it to, automatically organizing your files according to the rules you create. It features a rule interface [..]. Have Hazel move files around based on name, date, type, what site/email address it came from [..] and much more. Automatically put your music in your Music folder, movies in Movies. Keep your downloads off the desktop and put them where they are supposed to be." This question probably won't make sense unless you have used Hazel, but basically you can define rules via the GUI to move and rename files automatically to make an automated workflow.

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  • Inaccurate performance counter timer values in Windows Performance Monitor

    - by krisg
    I am implementing instrumentation within an application and have encountered an issue where the value that is displayed in Windows Performance Monitor from a PerformanceCounter is incongruent with the value that is recorded. I am using a Stopwatch to record the duration of a method execution, then first i record the total milliseconds as a double, and secondly i pass the Stopwatch's TimeSpan.Ticks to the PerformanceCounter to be recorded in the Performance Monitor. Creating the Performance Counters in perfmon: var datas = new CounterCreationDataCollection(); datas.Add(new CounterCreationData { CounterName = name, CounterType = PerformanceCounterType.AverageTimer32 }); datas.Add(new CounterCreationData { CounterName = namebase, CounterType = PerformanceCounterType.AverageBase }); PerformanceCounterCategory.Create("Category", "performance data", PerformanceCounterCategoryType.SingleInstance, datas); Then to record i retrieve a pre-initialized counter from a collection and increment: _counters[counter].IncrementBy(timing); _counters[counterbase].Increment(); ...where "timing" is the Stopwatch's TimeSpan.Ticks value. When this runs, the collection of double's, which are the milliseconds values for the Stopwatch's TimeSpan show one set of values, but what appears in PerfMon are a different set of values. For example... two values recorded in the List of milliseconds are: 23322.675, 14230.614 And what appears in PerfMon graph are: 15.546, 9.930 Can someone explain this please?

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  • Why is Software Engineering not the typical major for future software developers?

    - by FarmBoy
    While most agree that a certain level of Computer Science is essential to being a good programmer, it seems to me that the principles of good software development is even more important, though not as fundamental. Just like mechanical engineers take physics classes, but far more engineering classes, I would expect, now that software is over a half century old, that software development would begin to dominate the undergraduate curriculum. But I don't see much evidence of this. Is there a reason that Software Engineering hasn't taken hold as an academic discipline?

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  • What are some good Software Engineering books for people who didn't formally study Computer Science or Software Engineering?

    - by Kugathasan Abimaran
    I'm a graduate in the electronic & telecommunication field, but working in a software company. I want to continue in this field and going for Masters in it. Can you recommend me some of the best books on software engineering, which cover almost all the topics in software engineering. I am not looking for books about coding practices such as Code Complete, Pragmatic Programmer, but rather general software engineering references.

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  • How to re-install Software Center?

    - by Icedrake
    I've had a problem with Software Center for a few weeks, where it has just refused to delete a removed PPA from its "All Software" and "Installed Software" drop-down menus. I've tried many suggested solutions, none have worked, so I've finally decided to re-install Software Center if its possible. How do you do this and is it risky to your computer (i.e. will re-installing it cause all sorts of issues)?

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  • Ubuntu Software Center Missing and cannot install?

    - by luqman
    My ubuntu was remove ubuntu software center because i want to reinstall again.but i used terminal...i cannot to install ubuntu software center.. :~$ sudo apt-get install software-center Reading package lists... Done Building dependency tree Reading state information... Done Package software-center is not available, but is referred to by another package. This may mean that the package is missing, has been obsoleted, or is only available from another source Why?

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  • Who decides what category the software in the Ubuntu Software Centre is filed under, and who can we report errors to?

    - by coversnail
    I noticed when browsing through the Ubuntu Software Centre that some programs seem to be placed in the wrong categories, for example Pinta, an image editor, appears under Developer Tools (instead of Graphics) in my list of installed programs. Is this a case of the developer incorrectly categorising their software when they uploaded it to the software centre, or does Canonical decided what goes where? And if we notice an obvious mistake who do we inform, the software developer or file a bug somehow?

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  • How to uninstall Ubuntu Software Center in 11.10?

    - by sainath
    I am trying to uninstall software center for ubuntu oneric using the command sudo apt-get remove software center and get this as result Reading package lists... Done Building dependency tree Reading state information... Done E: Unable to locate package software E: Unable to locate package center I did it once and got it fixed but now it does't work. I have an issue with the software center it keeps on repeatedly giving message saying send error.

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  • Various problems with software raid1 array built with Samsung 840 Pro SSDs

    - by Andy B
    I am bringing to ServerFault a problem that is tormenting me for 6+ months. I have a CentOS 6 (64bit) server with an md software raid-1 array with 2 x Samsung 840 Pro SSDs (512GB). Problems: Serious write speed problems: root [~]# time dd if=arch.tar.gz of=test4 bs=2M oflag=sync 146+1 records in 146+1 records out 307191761 bytes (307 MB) copied, 23.6788 s, 13.0 MB/s real 0m23.680s user 0m0.000s sys 0m0.932s When doing the above (or any other larger copy) the load spikes to unbelievable values (even over 100) going up from ~ 1. When doing the above I've also noticed very weird iostat results: Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util sda 0.00 1589.50 0.00 54.00 0.00 13148.00 243.48 0.60 11.17 0.46 2.50 sdb 0.00 1627.50 0.00 16.50 0.00 9524.00 577.21 144.25 1439.33 60.61 100.00 md1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 md2 0.00 0.00 0.00 1602.00 0.00 12816.00 8.00 0.00 0.00 0.00 0.00 md0 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 And it keeps it this way until it actually writes the file to the device (out from swap/cache/memory). The problem is that the second SSD in the array has svctm and await roughly 100 times larger than the second. For some reason the wear is different between the 2 members of the array root [~]# smartctl --attributes /dev/sda | grep -i wear 177 Wear_Leveling_Count 0x0013 094% 094 000 Pre-fail Always - 180 root [~]# smartctl --attributes /dev/sdb | grep -i wear 177 Wear_Leveling_Count 0x0013 070% 070 000 Pre-fail Always - 1005 The first SSD has a wear of 6% while the second SSD has a wear of 30%!! It's like the second SSD in the array works at least 5 times as hard as the first one as proven by the first iteration of iostat (the averages since reboot): Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util sda 10.44 51.06 790.39 125.41 8803.98 1633.11 11.40 0.33 0.37 0.06 5.64 sdb 9.53 58.35 322.37 118.11 4835.59 1633.11 14.69 0.33 0.76 0.29 12.97 md1 0.00 0.00 1.88 1.33 15.07 10.68 8.00 0.00 0.00 0.00 0.00 md2 0.00 0.00 1109.02 173.12 10881.59 1620.39 9.75 0.00 0.00 0.00 0.00 md0 0.00 0.00 0.41 0.01 3.10 0.02 7.42 0.00 0.00 0.00 0.00 What I've tried: I've updated the firmware to DXM05B0Q (following reports of dramatic improvements for 840Ps after this update). I have looked for "hard resetting link" in dmesg to check for cable/backplane issues but nothing. I have checked the alignment and I believe they are aligned correctly (1MB boundary, listing below) I have checked /proc/mdstat and the array is Optimal (second listing below). root [~]# fdisk -ul /dev/sda Disk /dev/sda: 512.1 GB, 512110190592 bytes 255 heads, 63 sectors/track, 62260 cylinders, total 1000215216 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00026d59 Device Boot Start End Blocks Id System /dev/sda1 2048 4196351 2097152 fd Linux raid autodetect Partition 1 does not end on cylinder boundary. /dev/sda2 * 4196352 4605951 204800 fd Linux raid autodetect Partition 2 does not end on cylinder boundary. /dev/sda3 4605952 814106623 404750336 fd Linux raid autodetect root [~]# fdisk -ul /dev/sdb Disk /dev/sdb: 512.1 GB, 512110190592 bytes 255 heads, 63 sectors/track, 62260 cylinders, total 1000215216 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x0003dede Device Boot Start End Blocks Id System /dev/sdb1 2048 4196351 2097152 fd Linux raid autodetect Partition 1 does not end on cylinder boundary. /dev/sdb2 * 4196352 4605951 204800 fd Linux raid autodetect Partition 2 does not end on cylinder boundary. /dev/sdb3 4605952 814106623 404750336 fd Linux raid autodetect /proc/mdstat root # cat /proc/mdstat Personalities : [raid1] md0 : active raid1 sdb2[1] sda2[0] 204736 blocks super 1.0 [2/2] [UU] md2 : active raid1 sdb3[1] sda3[0] 404750144 blocks super 1.0 [2/2] [UU] md1 : active raid1 sdb1[1] sda1[0] 2096064 blocks super 1.1 [2/2] [UU] unused devices: Running a read test with hdparm root [~]# hdparm -t /dev/sda /dev/sda: Timing buffered disk reads: 664 MB in 3.00 seconds = 221.33 MB/sec root [~]# hdparm -t /dev/sdb /dev/sdb: Timing buffered disk reads: 288 MB in 3.01 seconds = 95.77 MB/sec But look what happens if I add --direct root [~]# hdparm --direct -t /dev/sda /dev/sda: Timing O_DIRECT disk reads: 788 MB in 3.01 seconds = 262.08 MB/sec root [~]# hdparm --direct -t /dev/sdb /dev/sdb: Timing O_DIRECT disk reads: 534 MB in 3.02 seconds = 176.90 MB/sec Both tests increase but /dev/sdb doubles while /dev/sda increases maybe 20%. I just don't know what to make of this. As suggested by Mr. Wagner I've done another read test with dd this time and it confirms the hdparm test: root [/home2]# dd if=/dev/sda of=/dev/null bs=1G count=10 10+0 records in 10+0 records out 10737418240 bytes (11 GB) copied, 38.0855 s, 282 MB/s root [/home2]# dd if=/dev/sdb of=/dev/null bs=1G count=10 10+0 records in 10+0 records out 10737418240 bytes (11 GB) copied, 115.24 s, 93.2 MB/s So sda is 3 times faster than sdb. Or maybe sdb is doing also something else besides what sda does. Is there some way to find out if sdb is doing more than what sda does? UPDATE Again, as suggested by Mr. Wagner, I have swapped the 2 SSDs. And as he thought it would happen, the problem moved from sdb to sda. So I guess I'll RMA one of the SSDs. I wonder if the cage might be problematic. What is wrong with this array? Please help!

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  • mysql settings - using the available resources

    - by Christian Payne
    I've got a lot of processing work I need to run on a mysql server. I've installed mysql 5.1.45-community on a Win 2007 64bit. Its running on a xenon, 3ghz 6 processors with 8 gig ram. It doesn't seem to matter what queries I run (or the number I run at the same time), when I look in task manager, I'll see one processor is out at 100%. The other 5 are idol. Memory is static at 1.54 gig. When I installed mysql, I used the wizard and selected the default "server" (not workstation) option. I feel like I should be getting more bang for my buck. Is there something else I should be monitoring or something I should change to use the other system resources???

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  • Evolución de software, los nuevos desafíos de la actual industria de software

    Evolución de software, los nuevos desafíos de la actual industria de software En este programa presentaremos una visión general de las oportunidades tecnológicas que favorecen la generación de emprendimientos regionales desde el equipo de relaciones para desarrolladores de la región de sur de Latinoamérica. Trataremos escenarios tecnológicos y principalmente el impacto en la evolución de software y el modelo de computación en la nube, finalmente analizaremos las oportunidades más importantes junto a diversos referentes regionales. Tecnología, desafíos, opiniones y todo el ecosistema representado por la pasión y el talento regional. From: GoogleDevelopers Views: 0 0 ratings Time: 02:00:00 More in Education

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  • SQL SERVER – DMV to Identify Incremental Statistics – Performance improvements in SQL Server 2014 – Part 3

    - by Pinal Dave
    This is the third part of the series Incremental Statistics. Here is the index of the complete series. What is Incremental Statistics? – Performance improvements in SQL Server 2014 – Part 1 Simple Example of Incremental Statistics – Performance improvements in SQL Server 2014 – Part 2 DMV to Identify Incremental Statistics – Performance improvements in SQL Server 2014 – Part 3 In earlier two parts we have seen what is incremental statistics and its simple example. In this blog post we will be discussing about DMV, which will list all the statistics which are enabled for Incremental Updates. SELECT  OBJECT_NAME(sys.stats.OBJECT_ID) AS TableName, sys.columns.name AS ColumnName, sys.stats.name AS StatisticsName FROM   sys.stats INNER JOIN sys.stats_columns ON sys.stats.OBJECT_ID = sys.stats_columns.OBJECT_ID AND sys.stats.stats_id = sys.stats_columns.stats_id INNER JOIN sys.columns ON sys.stats.OBJECT_ID = sys.columns.OBJECT_ID AND sys.stats_columns.column_id = sys.columns.column_id WHERE   sys.stats.is_incremental = 1 If you run above script in the example displayed, in part 1 and part 2 you will get resultset as following. When you execute the above script, it will list all the statistics in your database which are enabled for Incremental Update. The script is very simple and effective. If you have any further improved script, I request you to post in the comment section and I will post that on blog with due credit. Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: PostADay, SQL, SQL Authority, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, T SQL Tagged: SQL Statistics, Statistics

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  • SQL SERVER – Cardinality Estimation and Performance – SQL in Sixty Seconds #072

    - by Pinal Dave
    Yesterday I wrote blog post based on my latest Pluralsight course on learning SQL Server 2014. I discussed newly introduced cardinality estimation in SQL Server 2014 and how it improves the performance of the query. The cardinality estimation logic is responsible for quality of query plans and majorly responsible for improving performance for any query. This logic was not updated for quite a while, but in the latest version of SQL Server 2104 this logic is re-designed. The new logic now incorporates various assumptions and algorithms of OLTP and warehousing workload. I hope my earlier blog post clearly explained how new cardinality estimation logic improves performance. If not, I suggest you watch following quick video where I explain this concept in extremely simple words. You can download the code used in this course from Simple Demo of New Cardinality Estimation Features of SQL Server 2014. Action Item Here are the blog posts I have previously written. You can read it over here: Simple Demo of New Cardinality Estimation Features of SQL Server 2014 Pluralsight Course You can subscribe to my YouTube Channel for frequent updates. Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: PostADay, SQL, SQL Authority, SQL Performance, SQL Query, SQL Server, SQL Server Management Studio, SQL Tips and Tricks, T SQL, Video

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  • Tips for debugging Samba performance?

    - by j-g-faustus
    Samba gives me 24 MB/s read and 44 MB/s write, while ftp gives 97 and 112 MB/s under the same circumstances. The documentation says that Generally, you should find that Samba performs similarly to ftp at raw transfer speed. In my case it clearly doesn't. Where can I find tips on how to debug Samba performance? Or alternatively tips for replacing Samba with something else? (I can't use ftp, unfortunately, as I need something that can be used with rsync/rsnapshot.) More details: Both computers are running Ubuntu 10.10 (using Samba because I have a Mac as well) The Samba share is on a local home network, mounted as $ mount ... //server.local/share/ on /mnt/share type cifs (rw,mand) Samba performance was tested by copying (cp) a single file of ~4GB to and from the share, using time for timing and calculating transfer speed by hand. ftp performance are the numbers from the ftp client for get/put of the same file. iperf gives network speed ~900 Mbits/s bonnie++ gives disk speeds 200 MB/s on both sides for block reads as well as block writes Tried changing the parameters suggested in the performance tuning HOWTO (read/write raw, read size, socket options), most of them made little to no difference. (The one that made a difference caused write speed to drop 50%.)

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  • Best Method For Evaluating Existing Software or New Software

    How many of us have been faced with having to decide on an off-the-self or a custom built component, application, or solution to integrate in to an existing system or to be the core foundation of a new system? What is the best method for evaluating existing software or new software still in the design phase? One of the industry preferred methodologies to use is the Active Reviews for Intermediate Designs (ARID) evaluation process.  ARID is a hybrid mixture of the Active Design Review (ADR) methodology and the Architectural Tradeoff Analysis Method (ATAM). So what is ARID? ARD’s main goal is to ensure quality, detailed designs in software. One way in which it does this is by empowering reviewers by assigning generic open ended survey questions. This approach attempts to remove the possibility for allowing the standard answers such as “Yes” or “No”. The ADR process ignores the “Yes”/”No” questions due to the fact that they can be leading based on how the question is asked. Additionally these questions tend to receive less thought in comparison to more open ended questions. Common Active Design Review Questions What possible exceptions can occur in this component, application, or solution? How should exceptions be handled in this component, application, or solution? Where should exceptions be handled in this component, application, or solution? How should the component, application, or solution flow based on the design? What is the maximum execution time for every component, application, or solution? What environments can this component, application, or solution? What data dependencies does this component, application, or solution have? What kind of data does this component, application, or solution require? Ok, now I know what ARID is, how can I apply? Let’s imagine that your organization is going to purchase an off-the-shelf (OTS) solution for its customer-relationship management software. What process would we use to ensure that the correct purchase is made? If we use ARID, then we will have a series of 9 steps broken up by 2 phases in order to ensure that the correct OTS solution is purchases. Phase 1 Identify the Reviewers Prepare the Design Briefing Prepare the Seed Scenarios Prepare the Materials When identifying reviewers for a design it is preferred that they be pulled from a candidate pool comprised of developers that are going to implement the design. The believe is that developers actually implementing the design will have more a vested interest in ensuring that the design is correct prior to the start of code. Design debriefing consist of a summary of the design, examples of the design solving real world examples put in to use and should be no longer than two hours typically. The primary goal of this briefing is to adequately summarize the design so that the review members could actually implement the design. In the example of purchasing an OTS product I would attempt to review my briefing prior to its distribution with the review facilitator to ensure that nothing was excluded that should have not been. This practice will also allow me to test the length of the briefing to ensure that can be delivered in an appropriate about of time. Seed Scenarios are designed to illustrate conceptualized scenarios when applied with a set of sample data. These scenarios can then be used by the reviewers in the actual evaluation of the software, All materials needed for the evaluation should be prepared ahead of time so that they can be reviewed prior to and during the meeting. Materials Included: Presentation Seed Scenarios Review Agenda Phase 2 Present ARID Present Design Brainstorm and prioritize scenarios Apply scenarios Summarize Prior to the start of any ARID review meeting the Facilitator should define the remaining steps of ARID so that all the participants know exactly what they are doing prior to the start of the review process. Once the ARID rules have been laid out, then the lead designer presents an overview of the design which typically takes about two hours. During this time no questions about the design or rational are allowed to be asked by the review panel as a standard, but they are written down for use latter in the process. After the presentation the list of compiled questions is then summarized and sent back to the lead designer as areas that need to be addressed further. In the example of purchasing an OTS product issues could arise regarding security, the implementation needed or even if this is this the correct product to solve the needed solution. After the Design presentation a brainstorming and prioritize scenarios process begins by reducing the seed scenarios down to just the highest priority scenarios.  These will then be used to test the design for suitability. Once the selected scenarios have been defined the reviewers apply the examples provided in the presentation to the scenarios. The intended output of this process is to provide code or pseudo code that makes use of the examples provided while solving the selected seed scenarios. As a standard rule, the designers of the systems are not allowed to help the review board unless they all become stuck. When this occurs it is documented and along with the reason why the designer needed to help the review panel back on track. Once all of the scenarios have been completed the review facilitator reviews with the group issues that arise during the process. Then the reviewers will be polled as to efficacy of the review experience. References: Clements, Paul., Kazman, Rick., Klien, Mark. (2002). Evaluating Software Architectures: Methods and Case Studies Indianapolis, IN: Addison-Wesley

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  • Create software without programming

    - by Hafizul Amri
    Is there any system or software that can let you create a system or software without have to do programming? UPDATE: Answering to Kennethvr question. Software that I mean is like a web-based software that used to create a simple CRUD system such contact management system, and you can choose how data will be displayed. UPDATE I have found PHPRunner software. It can create a simple CRUD system without you need to touch your coding. Take a look at it!

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  • Ubuntu Software Center is crashing while trying to install psychonauts

    - by GonzoDark
    I am having a problem installing Tim Schafers epic platform video game Psychonauts trough the Ubuntu Software Center. I have bought the game on http://www.humblebundle.com/ and I have used the new redeem option introduced in this bundle: "redeem your bundle on the Ubuntu Software Center." When I have downloaded approximately 2.1 GB of Psychonauts then Ubuntu Software Center starts to repeatedly crash and pop-up with a new crash report dialog every few seconds (before previous ones are closed and that will crash the computer after a few min, unless I stop the download). I also have a file-size bug, where Ubuntu Software Center tells me that I have downloaded 880,2 MB out of 133,3 MB I use the new Ubuntu 12.04 LTS and Ubuntu Software Center version 5.2.2.2 (©2009-2011 Canonical <--- That is also a bug, should be 2012 I guess) I hope someone can help me.

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  • How to update the USB Ubuntu (ISO) with new software

    - by nakata
    I have Peppermint (based on Ubuntu) running of USB. Its bascially an ISO image that loads using Grub4Dos. Problem is that I each time I load Ubuntu - and want to use i.e. teamviewer or Firefox...I have to install it on the running live system. Since its running from a ISO image...a reboot means the software is gone. I can edit/open the ISO image using WinImage (on XP) - would you know how I can add extra software into this ISO image so next time Ubuntu loads...the new software is on there? Is there some special repositary director where I should copy the software files into and recreate the ISO image? The directory structure of this iso image is along the lines of: .disk [BOOT] Casper dists install isolinux pool preseed Appreciate your help with this. The software I am really interested in installing is the plugin for LogMeIn (for which I may need Firefox...thus I need Firefox installation) and Teamviewer. Thanks Nakata

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  • Excel-based Performance Reviews transformed into Web Application for Performance Management

    - by Webgui
    HR TMS provides enterprise talent management solutions for healthcare, retail and corporate customers, focusing on performance management, compensation management and succession planning. As the competency of nurses and other healthcare workers is critical, the government, via the Joint Commission (JCAHO), tightly monitors their performances. On a regular basis, accredited healthcare organizations are required to review employee performance using a complex set of position dependent job descriptions and competencies. Middlesex Hospital managed their performance reviews for 2500 employees manually with Excel spreadsheets. This was a labor intensive process that proved to be error prone and difficult to manage. Reviews were not always where they belonged and the job descriptions and competencies for healthcare workers were difficult to keep accurate and up to date. As a result, when the Joint Commission visited and requested to see specific review documentation, there was intense stress. Middlesex Hospital needed to automate their review process, pull in the position information from those spreadsheets and be able to deliver reviews online. Users needed to have online access to those reviews from a standard browser. Although the manual system had its issues, it did have the advantage of being very comprehensive and familiar to users. The decision was made to provide a web-based solution that leveraged the look and feel of those spreadsheets in order to insure user acceptance of the system and minimize the training needed. Read the full article here >

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  • What industries develop the highest quality software? Lowest quality? Why?

    - by Derek Mahar
    From your experience, of those industries that develop custom software for internal use such as financial services companies, which ones produce higher quality software measured in defect rates and, more qualitatively, ease of maintenance over the long term? What contributes the most to this achievement of higher quality? Is it due to better software development practices such as greater emphasis on testing or specification? Developers who better understand the tools or who are strong problem solvers? Better communication between team members? On the flip-side, which industries do you think produce the lowest quality software? Why?

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