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  • MS Access vs SQL Server and others ? Is it worth taking a db server when less than 2 Gb and only 20

    - by asksuperuser
    After my experiment with MSAccess vs MySQL which shows MS Access hugely overperforming Mysql odbc insert by a factor 1000% before I would do the same experiment with SQL Server I searched for some other's people and found this one: http://blog.nkadesign.com/2009/access-vs-sql-server-some-stats-part-1/ which says "As a side note, in this particular test, Access offers much better raw performance than SQL Server. In more complex scenarios it’s very likely that Access’ performance would degrade more than SQL Server, but it’s nice to see that Access isn’t a sloth." So is worth bother with some db server when data is less than 2 Gb and users are about 20 (knowing that MS Access theorically supports up to 255 concurrent users though practically it's around a dozen concurrent users only). Are there any real world studies that really compare MS Access with other db in these specific use case ? Because professionaly speaking I keep hearing people systematically recommend DB server from people who have never used Access just because they think DB Server can only perform better in every case which I used to think myself I confess.

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  • In Java, is there a performance gain in using interfaces for complex models?

    - by Gnoupi
    The title is hardly understandable, but I'm not sure how to summarize that another way. Any edit to clarify is welcome. I have been told, and recommended to use interfaces to improve performances, even in a case which doesn't especially call for the regular "interface" role. In this case, the objects are big models (in a MVC meaning), with many methods and fields. The "good use" that has been recommended to me is to create an interface, with its unique implementation. There won't be any other class implementing this interface, for sure. I have been told that this is better to do so, because it "exposes less" (or something close) to the other classes which will use methods from this class, as these objects are referring to the object from its interface (all public methods from the implementation being reproduced in the interface). This seems quite strange to me, as it seems like a C++ use to me (with header files). There I see the point, but in Java? Is there really a point in making an interface for such unique implementation? I would really appreciate some clarifications on the topic, so I could justify not following such kind of behavior, and the hassle it creates from duplicating all declarations. Edit: Plenty of valid points in most answers, I'm wondering if I won't switch this question for a community wiki, so we can regroup these points in more structured answers.

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  • How to use LINQ for CRUD with a simple SQL table?

    - by Rob Ferno
    Every LINQ blog I found there seemed around 2 years old, I understand the syntax but need more direction on creating the SQL mapping and context classes. I just need to use LINQ for 2 SQL tables I have, nothing complicated. Do folks write the SQL mapping classes by hand for such cases or is there a decent tool for this? Can someone point me in the right direction?

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  • Which one has a faster runtime performance: WPF or Winforms?

    - by Joan Venge
    I know WPF is more complex an flexible so could be thought to do more calculations. But since the rendering is done on the GPU, wouldn't it be faster than Winforms for the same application (functionally and visually)? I mean when you are not running any games or heavy 3d rendering, the GPU isn't doing heavy work, right? Whereas the CPU is always busy. Is this a valid assumption or is the GPU utilization of WPF a very minor operation in its pipeline?

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  • When does code bloat start having a noticeable effect on performance?

    - by Kyle
    I am looking to make a hefty shift towards templates in one of my OpenGL projects, mainly for fun and the learning experience. I plan on watching the size of the executable carefully as I do this, to see just how much of the notorious bloat happens. Currently, the size of my Release build is around 580 KB when I favor speed and 440 KB when I favor size. Yes, it's a tiny project, and in fact even if my executable bloats 10 x its size, it's still going to be 5 MB or so, which hardly seems large by today's standards... or is it? This brings me to my question. Is speed proportional to size, or are there leaps and plateaus at certain thresholds, thresholds which I should be aiming to stay below? (And if so, what are the thresholds specifically?)

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  • How do I make use of multiple cores in Large SQL Server Queries?

    - by Jonathan Beerhalter
    I have two SQL Servers, one for production, and one as an archive. Every night, we've got a SQL job that runs and copies the days production data over to the archive. As we've grown, this process takes longer and longer and longer. When I watch the utilization on the archive server running the archival process, I see that it only ever makes use of a single core. And since this box has eight cores, this is a huge waste of resources. The job runs at 3AM, so it's free to take any and all resources it can find. So what I need to do if figure out how to structure SQL Server jobs so they can take advantage of multiple cores, but I can't find any literature on tackling this problem. We're running SQL Server 2005, but I could certainly push for an upgrade if 2008 takes of this problem.

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  • How can I compare the performance of log() and fp division in C++?

    - by Ventzi Zhechev
    Hi, I’m using a log-based class in C++ to store very small floating-point values (as the values otherwise go beyond the scope of double). As I’m performing a large number of multiplications, this has the added benefit of converting the multiplications to sums. However, at a certain point in my algorithm, I need to divide a standard double value by an integer value and than do a *= to a log-based value. I have overloaded the *= operator for my log-based class and the right-hand side value is first converted to a log-based value by running log() and than added to the left-hand side value. Thus the operations actually performed are floating-point division, log() and floating-point summation. My question whether it would be faster to first convert the denominator to a log-based value, which would replace the floating-point division with floating-point subtraction, yielding the following chain of operations: twice log(), floating-point subtraction, floating-point summation. In the end, this boils down to whether floating-point division is faster or slower than log(). I suspect that a common answer would be that this is compiler and architecture dependent, so I’ll say that I use gcc 4.2 from Apple on darwin 10.3.0. Still, I hope to get an answer with a general remark on the speed of these two operators and/or an idea on how to measure the difference myself, as there might be more going on here, e.g. executing the constructors that do the type conversion etc. Cheers!

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  • How big can a SQL Server row be before it's a problem?

    - by John Leidegren
    Occasionally I run into this limitation using SQL Server 2000 that a row size can not exceed 8K bytes. SQL Server 2000 isn't really state of the art, but it's still in production code and because some tables are denormalized that's a problem. However, this seems to be a non issue with SQL Server 2005. At least, it won't complain that row sizes are bigger than 8K, but what happens instead and why was this a problem in SQL Server 2000? Do I need to care about my rows growing? Should I try and avoid large rows? Are varchar(max) and varbinary(max) a solution or expensive, in terms of size in database and/or CPU time? Why do I care at all about specifying the length of a particular column, when it seems like it's just a matter of time before someones going to hit that upper limit?

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  • SQL Server Text type v.s. varchar data type

    - by George2
    Hello everyone, I have variable length character and want to store in SQL Server (2005) database. I want to learn some best practices about how to choose TEXT SQL type or choose VARCHAR SQL type, pros and cons in performance/footprint/function. thanks in advance, George

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  • What's best performance way to constantly change image on WP7?

    - by AlRodriguez
    I'm trying to make my own type of remote desktop for WP7. I have a WCF service that returns an image on what's on the target machine's screen. Here's the WCF Server Code: // Method to load desktop image Bitmap image = new Bitmap( ViewSize.Width, ViewSize.Height ); Graphics g = Graphics.FromImage( image ); g.CopyFromScreen( Position.X, Position.Y, 0, 0, ViewSize ); g.Dispose( ); return image; // Convert image to byte[] which is returned to client using ( MemoryStream ms = new MemoryStream( ) ) { Bitmap image = screenGrabber.LoadScreenImage( ); image.Save( ms, ImageFormat.Jpeg ); imageArray = ms.ToArray( ); } Here's the code for the WP7 client: MemoryStream stream = new MemoryStream( data ); BitmapImage image = new BitmapImage( ); image.SetSource( stream ); BackgroundImage.Source = image; The BackgroundImage variable is an Image control. I'm noticing this freeze on the emulator after a short while, and will eventually crash from an OutOfMemoryException. This is already pretty slow ( images show up a good half second later than what's on the screen ), and I'm wondering if there's a better/faster way of doing this? Any help would be great. Thanks in advance.

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  • Why do dicts of defaultdict(int)'s use so much memory? (and other simple python performance question

    - by dukhat
    import numpy as num from collections import defaultdict topKeys = range(16384) keys = range(8192) table = dict((k,defaultdict(int)) for k in topKeys) dat = num.zeros((16384,8192), dtype="int32") print "looping begins" #how much memory should this use? I think it shouldn't use more that a few #times the memory required to hold (16384*8192) int32's (512 mb), but #it uses 11 GB! for k in topKeys: for j in keys: dat[k,j] = table[k][j] print "done" What is going on here? Furthermore, this similar script takes eons to run compared to the first one, and also uses an absurd quantity of memory. topKeys = range(16384) keys = range(8192) table = [(j,0) for k in topKeys for j in keys] I guess python ints might be 64 bit ints, which would account for some of this, but do these relatively natural and simple constructions really produce such a massive overhead? I guess these scripts show that they do, so my question is: what exactly is causing the high memory usage in the first script and the long runtime and high memory usage of the second script and is there any way to avoid these costs?

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  • What does ‘?’ stand for in SQL?

    - by user295189
    I have this SQL by a programmer: $sql = " INSERT INTO `{$database}`.`table` ( `my_id`, `xType`, `subType`, `recordID`, `textarea` ) VALUES ( {$my_id}, ?xType, ?subType, {$recordID}, ?areaText ) "; My question is why is he using ? before values? How do I see what values are coming in? I did echo and it shows ?xType as ?xType. No values. What does ? stand for in SQL?

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  • ODBC in SSIS 2012

    - by jamiet
    In August 2011 the SQL Server client team published a blog post entitled Microsoft is Aligning with ODBC for Native Relational Data Access in which they basically said "OLE DB is the past, ODBC is the future. Deal with it.". From that blog post:We encourage you to adopt ODBC in the development of your new and future versions of your application. You don’t need to change your existing applications using OLE DB, as they will continue to be supported on Denali throughout its lifecycle. While this gives you a large window of opportunity for changing your applications before the deprecation goes into effect, you may want to consider migrating those applications to ODBC as a part of your future roadmap.I recently undertook a project using SSIS2012 and heeded that advice by opting to use ODBC Connection Managers rather than OLE DB Connection Managers. Unfortunately my finding was that the ODBC Connection Manager is not yet ready for primetime use in SSIS 2012. The main issue I found was that you can't populate an Object variable with a recordset when using an Execute SQL Task connecting to an ODBC data source; any attempt to do so will result in an error:"Disconnected recordsets are not available from ODBC connections." I have filed a bug on Connect at ODBC Connection Manager does not have same funcitonality as OLE DB. For this reason I strongly recommend that you don't make the move to ODBC Connection Managers in SSIS just yet - best to wait for the next version of SSIS before doing that.I found another couple of issues with the ODBC Connection Manager that are worth keeping in mind:It doesn't recognise System Data Source Names (DSNs), only User DSNs (bug filed at ODBC System DSNs are not available in the ODBC Connection Manager)  UPDATE: According to a comment on that Connect item this may only be a problem on 64bit.In the OLE DB Connection Manager parameter ordinals are 0-based, in the ODBC Connection Manager they are 1-based (oh I just can't wait for the upgrade mess that ensues from this one!!!)You have been warned!@jamiet

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  • Why the “Toilet” Analogy for SQL might be bad

    - by Jonathan Kehayias
    Robert Davis(blog/twitter) recently blogged The Toilet Analogy … or Why I Never Recommend Increasing Worker Threads , in which he uses an analogy for why increasing the value for the ‘max worker threads’ sp_configure option can be bad inside of SQL Server.  While I can’t make an argument against Robert’s assertion that increasing worker threads may not improve performance, I can make an argument against his suggestion that, simply increasing the number of logical processors, for example from...(read more)

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  • SSIS code smell – Unused columns in the dataflow

    - by jamiet
    A code smell is defined on Wikipedia as being a “symptom in the source code of a program that possibly indicates a deeper problem”. It’s a term commonly used by our code-writing brethren to describe sub-optimal code but I think the term can be applied equally well to SSIS packages too as I shall now explain One of my pet hates about SSIS development is packages that throw warnings of the form: The output column "ColumnName" (1358) on output "OLE DB Source Output" (1289) and component "OLE_SRC Name" (1279) is not subsequently used in the Data Flow task. Removing this unused output column can increase Data Flow task performance.  The warning is fairly self-explanatory – any column that appears in the data flow but doesn’t get used will throw this warning when the data flow is executed. Its not the negligible performance degradation that they cause that bothers me though, it’s the clutter that they cause in your log file/table. Take a look at the following screenshot if you don’t believe me: There are 231409 such warnings in the system that I took this screenshot from, that is 231409 log records that should not be there. The most infuriating thing about this warning is that it is so easily avoidable; eliminating such columns is a very quick and easy thing to do in the SSIS Designer. The only problem I see is that the warnings don’t occur until you execute the package – it would be preferable for the designer to have an unobtrusive way of informing you of them as well. Anyway, I digress… I consider such warnings to be a code smell because, to me, they’re symptomatic of a lack of due care and attention; a lack of developer discipline if you will. What other code smells can you think of when building SSIS packages? If I get a good list in the comments maybe I’ll compile them into a later blog post. @Jamiet Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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  • Could not continue scan with NOLOCK due to data movement during installation

    - by dbdev1
    I am running Windows Server 2008 Standard Edition R2 x64 and I installed SQL Server 2008 Developer Edition. All of the preliminary checks run fine (Apart from a warning about Windows Firewall and opening ports which is unrelated to this and shouldn't be an issue - I can open those ports). Half way through the actual installation, I get a popup with this error: Could not continue scan with NOLOCK due to data movement. The installation still runs to completion when I press ok. However, at the end, it states that the following services "failed": database engine services sql server replication full-text search reporting services How do I know if this actually means that anything from my installation (which is on a clean Windows Server setup - nothing else on there, no previous SQL Servers, no upgrades, etc) is missing? I know from my programming experience that locks are for concurrency control and the Microsoft help on this issue points to changing my query's lock/transactions in a certain way to fix the issue. But I am not touching any queries? Also, now that I have installed the app, when I login, I keep getting this message: TITLE: Connect to Server ------------------------------ Cannot connect to MSSQLSERVER. ------------------------------ ADDITIONAL INFORMATION: A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: Named Pipes Provider, error: 40 - Could not open a connection to SQL Server) (Microsoft SQL Server, Error: 67) For help, click: http://go.microsoft.com/fwlink?ProdName=Microsoft+SQL+Server&EvtSrc=MSSQLServer&EvtID=67&LinkId=20476 ------------------------------ BUTTONS: OK ------------------------------ I went into the Configuration Manager and enabled named pipes and restarted the service (this is something I have done before as this message is common and not serious). I have disabled Windows Firewall temporarily. I have checked the instance name against the error logs. Please advise on both of these errors. I think these two errors are related. Thanks

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  • How to improve Windows Aero desktop performance?

    - by Click Ok
    Sincerely I don't understand why in Windows Experience ratings, the "Game Graphics" in my pc is 5.0 and "Graphic Elements" (windows aero desktop performance) is 3.9. How it is possible? My VGA is nice for games but bad for Windows Desktop? What I can do to improve windows aero desktop performance?

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