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• Wrong statistics in AUX_STATS$ might puzzle the optimizer

  - by Mike Dietrich

  We do recommend the creation of System Statistics for quite a long time. Since Oracle 9i the optimizer works with a CPU and IO cost based model. And in order to give the optimizer some knowledge about the IO subsystem's performance and throughput - once System Statistics are collected - they'll get stored in AUX_STATS$. For this purpose in the old Oracle 9i days some default values had been defined - and you'll still find those defaults in Oracle Database 11g Release 2 in AUX_STATS$. But these old values don't reflect the performance of modern IO systems. So it might be a good best practice post upgrade to create fresh System Statistics if you haven't done this before.  You can collect System Statistics with: exec DBMS_STATS.GATHER_SYSTEM_STATS('start'); and end it later by executing: exec DBMS_STATS.GATHER_SYSTEM_STATS('stop'); You could also run DBMS_STATS.GATHER_SYSTEM_STATS('interval', interval=>N) instead where N is the number of minutes when statistics gathering is stopped automatically. Please make sure you'll do this on a real workload period. It won't make sense to gather these values while the database is in an idle state. You should do this ideally for several hours. It doesn't affect performance in a negative way as the values are anyway collected in V$SYSSTAT and V$SESSTAT. And in case you'd like to delete the stats and revert to the old default values you'd simply execute:exec DBMS_STATS.DELETE_SYSTEM_STATS; The tricky thing in Oracle Database 11.2 - and that's why I'm actually writing this blog post today - is bug9842771. This leads to wrong values in AUX_STATS$ for SREADTIM and MREADTIM by factor 1000 guiding the optimizer sometimes into the totally wrong directon. The workaround is to overwrite these values manually and divide them by 1000. Use the DBMS_STATS.SET_SYSTEM_STATS procedure. See this MOS Note:9842771.8 for the above bug for some further information. This issue is fixed in Oracle Database 11.2.0.3 and above. To get some background information about the statistics collected in please read this section in the Oracle Database 11.2 Performance Tuning Guide. And gathering System Statistics might have some implication if you have mixed workloads - and interacts with DB_FILE_MULTIBLOCK_READ_COUNT. For more information please read section 13.4.1.2.

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• How do I make this rendering thread run together with the main one?

  - by funk

  I'm developing an Android game and need to show an animation of an exploding bomb. It's a spritesheet with 1 row and 13 different images. Each image should be displayed in sequence, 200 ms apart. There is one Thread running for the entire game: package com.android.testgame; import android.graphics.Canvas; public class GameLoopThread extends Thread { static final long FPS = 10; // 10 Frames per Second private final GameView view; private boolean running = false; public GameLoopThread(GameView view) { this.view = view; } public void setRunning(boolean run) { running = run; } @Override public void run() { long ticksPS = 1000 / FPS; long startTime; long sleepTime; while (running) { Canvas c = null; startTime = System.currentTimeMillis(); try { c = view.getHolder().lockCanvas(); synchronized (view.getHolder()) { view.onDraw(c); } } finally { if (c != null) { view.getHolder().unlockCanvasAndPost(c); } } sleepTime = ticksPS - (System.currentTimeMillis() - startTime); try { if (sleepTime > 0) { sleep(sleepTime); } else { sleep(10); } } catch (Exception e) {} } } } As far as I know I would have to create a second Thread for the bomb. package com.android.testgame; import android.graphics.Bitmap; import android.graphics.Canvas; import android.graphics.Rect; public class Bomb { private final Bitmap bmp; private final int width; private final int height; private int currentFrame = 0; private static final int BMPROWS = 1; private static final int BMPCOLUMNS = 13; private int x = 0; private int y = 0; public Bomb(GameView gameView, Bitmap bmp) { this.width = bmp.getWidth() / BMPCOLUMNS; this.height = bmp.getHeight() / BMPROWS; this.bmp = bmp; x = 250; y = 250; } private void update() { currentFrame++; new BombThread().start(); } public void onDraw(Canvas canvas) { update(); int srcX = currentFrame * width; int srcY = height; Rect src = new Rect(srcX, srcY, srcX + width, srcY + height); Rect dst = new Rect(x, y, x + width, y + height); canvas.drawBitmap(bmp, src, dst, null); } class BombThread extends Thread { @Override public void run() { try { sleep(200); } catch(InterruptedException e){ } } } } The Threads would then have to run simultaneously. How do I do this?

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• Is There a Real Advantage to Generic Repository?

  - by Sam

  Was reading through some articles on the advantages of creating Generic Repositories for a new app (example). The idea seems nice because it lets me use the same repository to do several things for several different entity types at once: IRepository repo = new EfRepository(); // Would normally pass through IOC into constructor var c1 = new Country() { Name = "United States", CountryCode = "US" }; var c2 = new Country() { Name = "Canada", CountryCode = "CA" }; var c3 = new Country() { Name = "Mexico", CountryCode = "MX" }; var p1 = new Province() { Country = c1, Name = "Alabama", Abbreviation = "AL" }; var p2 = new Province() { Country = c1, Name = "Alaska", Abbreviation = "AK" }; var p3 = new Province() { Country = c2, Name = "Alberta", Abbreviation = "AB" }; repo.Add<Country>(c1); repo.Add<Country>(c2); repo.Add<Country>(c3); repo.Add<Province>(p1); repo.Add<Province>(p2); repo.Add<Province>(p3); repo.Save(); However, the rest of the implementation of the Repository has a heavy reliance on Linq: IQueryable<T> Query(); IList<T> Find(Expression<Func<T,bool>> predicate); T Get(Expression<Func<T,bool>> predicate); T First(Expression<Func<T,bool>> predicate); //... and so on This repository pattern worked fantastic for Entity Framework, and pretty much offered a 1 to 1 mapping of the methods available on DbContext/DbSet. But given the slow uptake of Linq on other data access technologies outside of Entity Framework, what advantage does this provide over working directly with the DbContext? I attempted to write a PetaPoco version of the Repository, but PetaPoco doesn't support Linq Expressions, which makes creating a generic IRepository interface pretty much useless unless you only use it for the basic GetAll, GetById, Add, Update, Delete, and Save methods and utilize it as a base class. Then you have to create specific repositories with specialized methods to handle all the "where" clauses that I could previously pass in as a predicate. Is the Generic Repository pattern useful for anything outside of Entity Framework? If not, why would someone use it at all instead of working directly with Entity Framework? Edit: Original link doesn't reflect the pattern I was using in my sample code. Here is an (updated link).

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• Function Folding in #PowerQuery

  - by Darren Gosbell

  Originally posted on: http://geekswithblogs.net/darrengosbell/archive/2014/05/16/function-folding-in-powerquery.aspxLooking at a typical Power Query query you will noticed that it's made up of a number of small steps. As an example take a look at the query I did in my previous post about joining a fact table to a slowly changing dimension. It was roughly built up of the following steps: Get all records from the fact table Get all records from the dimension table do an outer join between these two tables on the business key (resulting in an increase in the row count as there are multiple records in the dimension table for each business key) Filter out the excess rows introduced in step 3 remove extra columns that are not required in the final result set. If Power Query was to execute a query like this literally, following the same steps in the same order it would not be overly efficient. Particularly if your two source tables were quite large. However Power Query has a feature called function folding where it can take a number of these small steps and push them down to the data source. The degree of function folding that can be performed depends on the data source, As you might expect, relational data sources like SQL Server, Oracle and Teradata support folding, but so do some of the other sources like OData, Exchange and Active Directory. To explore how this works I took the data from my previous post and loaded it into a SQL database. Then I converted my Power Query expression to source it's data from that database. Below is the resulting Power Query which I edited by hand so that the whole thing can be shown in a single expression: let     SqlSource = Sql.Database("localhost", "PowerQueryTest"),     BU = SqlSource{[Schema="dbo",Item="BU"]}[Data],     Fact = SqlSource{[Schema="dbo",Item="fact"]}[Data],     Source = Table.NestedJoin(Fact,{"BU_Code"},BU,{"BU_Code"},"NewColumn"),     LeftJoin = Table.ExpandTableColumn(Source, "NewColumn"                                   , {"BU_Key", "StartDate", "EndDate"}                                   , {"BU_Key", "StartDate", "EndDate"}),     BetweenFilter = Table.SelectRows(LeftJoin, each (([Date] >= [StartDate]) and ([Date] <= [EndDate])) ),     RemovedColumns = Table.RemoveColumns(BetweenFilter,{"StartDate", "EndDate"}) in     RemovedColumns If the above query was run step by step in a literal fashion you would expect it to run two queries against the SQL database doing "SELECT * …" from both tables. However a profiler trace shows just the following single SQL query: select [_].[BU_Code],     [_].[Date],     [_].[Amount],     [_].[BU_Key] from (     select [$Outer].[BU_Code],         [$Outer].[Date],         [$Outer].[Amount],         [$Inner].[BU_Key],         [$Inner].[StartDate],         [$Inner].[EndDate]     from [dbo].[fact] as [$Outer]     left outer join     (         select [_].[BU_Key] as [BU_Key],             [_].[BU_Code] as [BU_Code2],             [_].[BU_Name] as [BU_Name],             [_].[StartDate] as [StartDate],             [_].[EndDate] as [EndDate]         from [dbo].[BU] as [_]     ) as [$Inner] on ([$Outer].[BU_Code] = [$Inner].[BU_Code2] or [$Outer].[BU_Code] is null and [$Inner].[BU_Code2] is null) ) as [_] where [_].[Date] >= [_].[StartDate] and [_].[Date] <= [_].[EndDate] The resulting query is a little strange, you can probably tell that it was generated programmatically. But if you look closely you'll notice that every single part of the Power Query formula has been pushed down to SQL Server. Power Query itself ends up just constructing the query and passing the results back to Excel, it does not do any of the data transformation steps itself. So now you can feel a bit more comfortable showing Power Query to your less technical Colleagues knowing that the tool will do it's best fold all the  small steps in Power Query down the most efficient query that it can against the source systems.

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• ASP.NET Web Forms is bad, or what am I missing?

  - by iveqy

  Being a PHP guy myself I recently had to write a spider to an asp.net site. I was really surprised by the different approach to ajax and form-handling. For example, in the PHP sites I've worked with, a deletion of a database entry would be something like: GET delete.php?id=&confirm=yes and get a "success" back in some form (in the ajax case, probably a json reply). In this asp.net application you would instead post a form, including all inputs on the page, with a huge __VIEWSTATE and __EVENTVALIDATION. This would be more than 10 times as big as above. The reply would be the complete side again, with a footer containing some structured data for javascript to parse and display the result. Again, the whole page is sent, and then throwed away(?) since it's already displayed. Why not just send the footer with the data to parse (it's not json nor xml but a | separated list). I really can't see why you would design a system that way. Usually you've a fast client, and a somewhat fast server but a really slow connection. Why not keep the datatransfer to a minimum? Why those huge __VIEWSTATE and __EVENTVALIDATION? It seems that everything is done way to chatty and way to complicated. I really can't see the point and that usually means that I'm missing something. So please tell me, what are the reasons for this design and what benefits (and weaknesses) does it have? (Yes I know that __VIEWSTATE is used to tell what type of form-konfiguration should be sent back to the server. But WHY is this needed?) Please keep this discussion strictly technical and avoid flamewars. Update: Please excuse the somewhat rantish question. I tried to explain my view to be able to get a better answer. I am not saying that asp.net is bad, I am saying that I don't understand the meaning of those concepts. Usually that means that I've things to learn instead of the concepts beeing wrong. I appreciate the explanations about that "you don't have to do this way in asp.net", I'll read up on MVC and other .net technologies. However, there most be a reason for this site (the one I referred to) to be written the way it is. It's written by professionals for a big organisation with far more experience than what I've. Any explanation about their (possible) design choice would be welcome.

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• Dealing with coworkers when developing, need advice [closed]

  - by Yippie-Kai-Yay

  I developed our current project architecture and started developing it on my own (reaching something like, revision 40). We're developing a simple subway routing framework and my design seemed to be done extremely well - several main models, corresponding views, main logic and data structures were modeled "as they should be" and fully separated from rendering, algorithmic part was also implemented apart from the main models and had a minor number of intersection points. I would call that design scalable, customizable, easy-to-implement, interacting mostly based on the "black box interaction" and, well, very nice. Now, what was done: I started some implementations of the corresponding interfaces, ported some convenient libraries and wrote implementation stubs for some application parts. I had the document describing coding style and examples of that coding style usage (my own written code). I forced the usage of more or less modern C++ development techniques, including no-delete code (wrapped via smart pointers) and etc. I documented the purpose of concrete interface implementations and how they should be used. Unit tests (mostly, integration tests, because there wasn't a lot of "actual" code) and a set of mocks for all the core abstractions. I was absent for 12 days. What do we have now (the project was developed by 4 other members of the team): 3 different coding styles all over the project (I guess, two of them agreed to use the same style :), same applies to the naming of our abstractions (e.g CommonPathData.h, SubwaySchemeStructures.h), which are basically headers declaring some data structures. Absolute lack of documentation for the recently implemented parts. What I could recently call a single-purpose-abstraction now handles at least 2 different types of events, has tight coupling with other parts and so on. Half of the used interfaces now contain member variables (sic!). Raw pointer usage almost everywhere. Unit tests disabled, because "(Rev.57) They are unnecessary for this project". ... (that's probably not everything). Commit history shows that my design was interpreted as an overkill and people started combining it with personal bicycles and reimplemented wheels and then had problems integrating code chunks. Now - the project still does only a small amount of what it has to do, we have severe integration problems, I assume some memory leaks. Is there anything possible to do in this case? I do realize that all my efforts didn't have any benefit, but the deadline is pretty soon and we have to do something. Did someone have a similar situation? Basically I thought that a good (well, I did everything that I could) start for the project would probably lead to something nice, however, I understand that I'm wrong. Any advice would be appreciated, sorry for my bad english.

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• No GRUB Screen or recovery mode on Boot after 12.04 Upgrade

  - by Nick

  I tried the live boot CD and boot-repair, also loaded the Desktop install CD, and it looks like all partitions check out OK. However, when I try to boot Linux (the only bootable partition on the computer) I get a blank screen. Every so often the screen give me something akin to: Assuming write through cache Asking for cache data failed it appears to start booting, then hangs. Ctrl+Alt+Delete shuts down the machine The last message during boot is "STarting TiMidity++ ALSA midi emulation... [OK]" I used boot-repair to generate a boot info report. One thing looks odd to me- it reports a missing core.img on /dev/sda1. Here is the full info: Boot Info Script 0.61.full + Boot-Repair extra info [Boot-Info August 2nd 2012] ============================= Boot Info Summary: =============================== = Grub2 (v1.99) is installed in the MBR of /dev/sda and looks at sector 1 of the same hard drive for core.img. core.img is at this location and looks for (,msdos1)/boot/grub on this drive. = Windows is installed in the MBR of /dev/sdb. sda1: __________________________________________ File system: ext4 Boot sector type: Grub2 (v1.99) Boot sector info: Grub2 (v1.99) is installed in the boot sector of sda1 and looks at sector 18406911 of the same hard drive for core.img, but core.img can not be found at this location. Operating System: Ubuntu 12.04.1 LTS Boot files: /boot/grub/grub.cfg /etc/fstab /boot/extlinux/extlinux.conf /boot/grub/core.img sda2: __________________________________________ File system: Extended Partition Boot sector type: - Boot sector info: sda5: __________________________________________ File system: swap Boot sector type: - Boot sector info: sdb1: __________________________________________ File system: ntfs Boot sector type: Windows XP: NTFS Boot sector info: No errors found in the Boot Parameter Block. Operating System: Boot files: ============================ Drive/Partition Info: ============================= Drive: sda _______________________________________ Disk /dev/sda: 160.0 GB, 160041885696 bytes 255 heads, 63 sectors/track, 19457 cylinders, total 312581808 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes Partition Boot Start Sector End Sector # of Sectors Id System /dev/sda1 * 63 307,339,514 307,339,452 83 Linux /dev/sda2 307,339,515 312,576,704 5,237,190 5 Extended /dev/sda5 307,339,578 312,576,704 5,237,127 82 Linux swap / Solaris Drive: sdb _______________________________________ Disk /dev/sdb: 320.1 GB, 320072933376 bytes 255 heads, 63 sectors/track, 38913 cylinders, total 625142448 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes Partition Boot Start Sector End Sector # of Sectors Id System /dev/sdb1 2,048 625,142,447 625,140,400 7 NTFS / exFAT / HPFS "blkid" output: ____________________________________ Device UUID TYPE LABEL /dev/loop0 squashfs /dev/sda1 11b4d633-7863-40b2-a6ca-da5f82c3ad0b ext4 /dev/sda5 cb8d65f4-8cf9-4088-b804-e3dea2151033 swap /dev/sdb1 349E7C109E7BC8BE ntfs Personal1 ================================ Mount points: ================================= Device Mount_Point Type Options /dev/sdb1 /media/Personal1 fuseblk (rw,nosuid,nodev,allow_other,blksize=4096,default_permissions) /dev/sr0 /live/image iso9660 (ro,noatime) ...(a bunch of config file info- let me know if anyone wants to see it!) But usually I just get "Cannot Display This Video Mode", which I know means the video output is not usable by the monitor. I'm looking for a way to get into a recovery mode.I'd really like to avoid wiping the drive. Any thoughts?

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• What algorithms can I use to detect if articles or posts are duplicates?

  - by michael

  I'm trying to detect if an article or forum post is a duplicate entry within the database. I've given this some thought, coming to the conclusion that someone who duplicate content will do so using one of the three (in descending difficult to detect): simple copy paste the whole text copy and paste parts of text merging it with their own copy an article from an external site and masquerade as their own Prepping Text For Analysis Basically any anomalies; the goal is to make the text as "pure" as possible. For more accurate results, the text is "standardized" by: Stripping duplicate white spaces and trimming leading and trailing. Newlines are standardized to \n. HTML tags are removed. Using a RegEx called Daring Fireball URLs are stripped. I use BB code in my application so that goes to. (ä)ccented and foreign (besides Enlgish) are converted to their non foreign form. I store information about each article in (1) statistics table and in (2) keywords table. (1) Statistics Table The following statistics are stored about the textual content (much like this post) text length letter count word count sentence count average words per sentence automated readability index gunning fog score For European languages Coleman-Liau and Automated Readability Index should be used as they do not use syllable counting, so should produce a reasonably accurate score. (2) Keywords Table The keywords are generated by excluding a huge list of stop words (common words), e.g., 'the', 'a', 'of', 'to', etc, etc. Sample Data text_length, 3963 letter_count, 3052 word_count, 684 sentence_count, 33 word_per_sentence, 21 gunning_fog, 11.5 auto_read_index, 9.9 keyword 1, killed keyword 2, officers keyword 3, police It should be noted that once an article gets updated all of the above statistics are regenerated and could be completely different values. How could I use the above information to detect if an article that's being published for the first time, is already existing within the database? I'm aware anything I'll design will not be perfect, the biggest risk being (1) Content that is not a duplicate will be flagged as duplicate (2) The system allows the duplicate content through. So the algorithm should generate a risk assessment number from 0 being no duplicate risk 5 being possible duplicate and 10 being duplicate. Anything above 5 then there's a good possibility that the content is duplicate. In this case the content could be flagged and linked to the article's that are possible duplicates and a human could decide whether to delete or allow. As I said before I'm storing keywords for the whole article, however I wonder if I could do the same on paragraph basis; this would also mean further separating my data in the DB but it would also make it easier for detecting (2) in my initial post. I'm thinking weighted average between the statistics, but in what order and what would be the consequences...

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• What is a good strategy for binding view objects to model objects in C++?

  - by B.J.

  Imagine I have a rich data model that is represented by a hierarchy of objects. I also have a view hierarchy with views that can extract required data from model objects and display the data (and allow the user to manipulate the data). Actually, there could be multiple view hierarchies that can represent and manipulate the model (e.g. an overview-detail view and a direct manipulation view). My current approach for this is for the controller layer to store a reference to the underlying model object in the View object. The view object can then get the current data from the model for display, and can send the model object messages to update the data. View objects are effectively observers of the model objects and the model objects broadcast notifications when properties change. This approach allows all the views to update simultaneously when any view changes the model. Implemented carefully, this all works. However, it does require a lot of work to ensure that no view or model objects hold any stale references to model objects. The user can delete model objects or sub-hierarchies of the model at any time. Ensuring that all the view objects that hold references to the model objects that have been deleted is time-consuming and difficult. It feels like the approach I have been taking is not especially clean; while I don't want to have to have explicit code in the controller layer for mediating the communication between the views and the model, it seems like there must be a better (implicit) approach for establishing bindings between the view and the model and between related model objects. In particular, I am looking for an approach (in C++) that understands two key points: There is a many to one relationship between view and model objects If the underlying model object is destroyed, all the dependent view objects must be cleaned up so that no stale references exist While shared_ptr and weak_ptr can be used to manage the lifetimes of the underlying model objects and allows for weak references from the view to the model, they don't provide for notification of the destruction of the underlying object (they do in the sense that the use of a stale weak_ptr allows for notification), but I need an approach that notifies the dependent objects that their weak reference is going away. Can anyone suggest a good strategy to manage this?

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• Writing or extending existing emacs packages: is it worth or should I move to Netbeans/Eclipse?

  - by Andrea

  I'm finishing my master degree course in CS and I've almost become addicted to Emacs. I've used it to write in C, Latex, Java, JSP,XML, CommonLisp, Ada and other languages no other editor supported, like AMPL. I'd like to improve the packages I've been using the most or create new ones, but, in practice, I find that the implementation of Emacs leaves a lot to be desired. There are a lot of poorly-featured/poorly-maintained packages with either overlapping functionalities or obscure incompatibilities, and Elisp just seems to foster the situation by lacking the common features modern lisps have. In contrast Eclipse and Netbeans are actively improved and it does seem they can be effective for non-mainstream languages. I tried Hibachi for Ada in Eclipse and it worked well, there's CUPS for Lisp in Eclipse and LambdaBeans built using NetBeans components. On the other hand those plugins seem to be less active than their Emacs' counterparts, for example Hibachi was archived last year. What's your opinion on this? Which editor should I write extension for? EDIT: To answer Larry Coleman (see comment below): I like Emacs as a user because it is efficient both for me and the computer I'm using. It's fast and the textual interface (i.e. minibuffer) allows for quick interaction. It's solid and packages are usually small and easy to manage. If I need to correct or remove something I usually just have to change a row in my .emacs or an elisp file, or delete a directory. Eclipse plugins rely on a more complicated process that screwed my Eclipse configuration a couple of times, forcing me to do a clean reinstall. Emacs works as long as I use the basic packages. If I need something more complicated the situation gets pretty hairy. As a "power user" I think that the best I can hope for is to write a severely crippled version of the extensions I'd actually like to have; in other words, that it's not worth the trouble. I'd like to write extensions for the things I'd like to have automated in Emacs, for example project support with automated tag-table update on file writing. There are a few projects on this that lack integration, documentation, extensibility and so forth. The best one is probably CEDET, for which I believe the Greenspun's 10th rule can be applied. EDIT: To comment Larry Coleman's answer I'm pretty sure I can pick elisp programming but the extensions I have in mind don't exist yet despite their relative simplicity and the effort more knowledgeable people poured into related projects.This makes me wonder whether it is so because of the way emacs is developed, i.e. people tend to write their own little extensions without coordination, or its implementation, its extension language not being able to keep up with the growing complexity.

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• Is 2 lines of push/pop code for each pre-draw-state too many?

  - by Griffin

  I'm trying to simplify vector graphics management in XNA; currently by incorporating state preservation. 2X lines of push/pop code for X states feels like too many, and it just feels wrong to have 2 lines of code that look identical except for one being push() and the other being pop(). The goal is to eradicate this repetitiveness,and I hoped to do so by creating an interface in which a client can give class/struct refs in which he wants restored after the rendering calls. Also note that many beginner-programmers will be using this, so forcing lambda expressions or other advanced C# features to be used in client code is not a good idea. I attempted to accomplish my goal by using Daniel Earwicker's Ptr class: public class Ptr<T> { Func<T> getter; Action<T> setter; public Ptr(Func<T> g, Action<T> s) { getter = g; setter = s; } public T Deref { get { return getter(); } set { setter(value); } } } an extension method: //doesn't work for structs since this is just syntatic sugar public static Ptr<T> GetPtr <T> (this T obj) { return new Ptr<T>( ()=> obj, v=> obj=v ); } and a Push Function: //returns a Pop Action for later calling public static Action Push <T> (ref T structure) where T: struct { T pushedValue = structure; //copies the struct data Ptr<T> p = structure.GetPtr(); return new Action( ()=> {p.Deref = pushedValue;} ); } However this doesn't work as stated in the code. How might I accomplish my goal? Example of code to be refactored: protected override void RenderLocally (GraphicsDevice device) { if (!(bool)isCompiled) {Compile();} //TODO: make sure state settings don't implicitly delete any buffers/resources RasterizerState oldRasterState = device.RasterizerState; DepthFormat oldFormat = device.PresentationParameters.DepthStencilFormat; DepthStencilState oldBufferState = device.DepthStencilState; { //Rendering code } device.RasterizerState = oldRasterState; device.DepthStencilState = oldBufferState; device.PresentationParameters.DepthStencilFormat = oldFormat; }

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• Alfa AWUS036H USB wireless adapter not recognized

  - by GFiasco

  The Alfa AWUS036H USB wireless adapter will not be recognized by my netbook (Ubuntu 14.04, Asus X201E). As I understand it, the drivers should already be built in to this version of Linux, but I tried a make/make install of the latest Realtek drivers (as mentioned on How do I install drivers for the Alfa AWUS036H USB wireless adapter?) and it didn't work. I then followed the advice of this thread (ALFA AWUS036NH driver) and did a make/make install of the most up-to-date backport of the drivers, but that didn't work. At this point I tried a series of commands from this thread (http://ubuntuforums.org/showthread.php?t=2187780) in an attempt to identify the problem, but at no point could I get the laptop to ever recognize the USB adapter. I have also troubleshot the USB cable itself, tried both the USB 2.0 and 3.0 ports on the laptop, have never received an error message regarding a need to update the firmware, and have seemingly successfully installed all manner of variation of Realtek drivers which were supposed to make the adapter work. (I also tried to delete/clean up after each install, in the hope I wasn't making things worse.) Not sure what I should do next. Please let me know if I need to post any more information. Thanks very much for your help. EDIT: Before inserting Alpha USB adapter: :~$ lsusb Bus 002 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 001 Device 004: ID 0bda:570c Realtek Semiconductor Corp. Bus 001 Device 026: ID 13d3:3393 IMC Networks Bus 001 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub Bus 003 Device 002: ID 03f0:3112 Hewlett-Packard Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub After inserting Alpha USB adapter (USB 3.0 port, no change): :~$ lsusb Bus 002 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 001 Device 004: ID 0bda:570c Realtek Semiconductor Corp. Bus 001 Device 026: ID 13d3:3393 IMC Networks Bus 001 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub Bus 003 Device 002: ID 03f0:3112 Hewlett-Packard Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Ran tail -f /var/log/syslog, inserted device, no recognition (last entry is dated 16:17:01, so an hour ago). Going to check on an Ubuntu 14.04 laptop and Windows XP desktop. I'll update after. Thanks for your help to this point.

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• Updating an Entity through a Service

  - by GeorgeK

  I'm separating my software into three main layers (maybe tiers would be a better term): Presentation ('Views') Business logic ('Services' and 'Repositories') Data access ('Entities' (e.g. ActiveRecords)) What do I have now? In Presentation, I use read-only access to Entities, returned from Repositories or Services, to display data. $banks = $banksRegistryService->getBanksRepository()->getBanksByCity( $city ); $banksViewModel = new PaginatedList( $banks ); // some way to display banks; // example, not real code I find this approach quite efficient in terms of performance and code maintanability and still safe as long as all write operations (create, update, delete) are preformed through a Service: namespace Service\BankRegistry; use Service\AbstractDatabaseService; use Service\IBankRegistryService; use Model\BankRegistry\Bank; class Service extends AbstractDatabaseService implements IBankRegistryService { /** * Registers a new Bank * * @param string $name Bank's name * @param string $bik Bank's Identification Code * @param string $correspondent_account Bank's correspondent account * * @return Bank */ public function registerBank( $name, $bik, $correspondent_account ) { $bank = new Bank(); $bank -> setName( $name ) -> setBik( $bik ) -> setCorrespondentAccount( $correspondent_account ); if( null === $this->getBanksRepository()->getDefaultBank() ) $this->setDefaultBank( $bank ); $this->getEntityManager()->persist( $bank ); return $bank; } /** * Makes the $bank system's default bank * * @param Bank $bank * @return IBankRegistryService */ public function setDefaultBank( Bank $bank ) { $default_bank = $this->getBanksRepository()->getDefaultBank(); if( null !== $default_bank ) $default_bank->setDefault( false ); $bank->setDefault( true ); return $this; } } Where am I stuck? I'm struggling about how to update certain fields in Bank Entity. Bad solution #1: Making a series of setters in Service for each setter in Bank; - seems to be quite reduntant, increases Service interface complexity and proportionally decreases it's simplicity - something to avoid if you care about code maitainability. I try to follow KISS and DRY principles. Bad solution #2: Modifying Bank directly through it's native setters; - really bad. If you'll ever need to move modification into the Service, it will be pain. Business logic should remain in Business logic layer. Plus, there are plans on logging all of the actions and maybe even involve user permissions (perhaps, through decorators) in future, so all modifications should be made only through the Service. Possible good solution: Creating an updateBank( Bank $bank, $array_of_fields_to_update) method; - makes the interface as simple as possible, but there is a problem: one should not try to manually set isDefault flag on a Bank, this operation should be performed through setDefaultBank method. It gets even worse when you have relations that you don't want to be directly modified. Of course, you can just limit the fields that can be modified by this method, but how do you tell method's user what they can and cannot modify? Exceptions?

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• Can't install alternate CD from USB?

  - by mattias

  Hi im trying to install ubuntu 12.04 with full hard disk encryption. After downloading and installing the Ubuntu live CD, I learned that truecrypt doesnt support full disk encryption on linux. I also learned that the best way to get "nearly full disk encryption" on ubuntu is by installing it from the alternate install CD. I tried that, but something is wrong with my CD reader/burner so it doesnt boot up when i insert the cd. My thought here was to take the .iso that I downloaded on my unencrypted Ubuntu system, use Unetbootin to make the usb drive. The usb drive used for this is exactly the same brand as one that I know has worked with a previous ubuntu live system on the same computer. I also used unetbootin for that usb, but I created it from windows that time. The usb stick boots up fine and i get through the first couple of steps in the installation process. However, After a while I get a "box" with the following error message "Load Installer components from CD" There was a problem reading data from the CD-ROM. Please make sure it is in the drive. If retrying does not work, you should check the integrity of your CD-ROM. "Failed to copy file from CD-ROM. Retry? " Then I cant get any further. I googled a lot and found this page which seems to tackle this very problem: http://www.dotkam.com/2010/11/29/ins...mage-from-usb/ I tried to do what it said. After pressing TAB, I wrote : cdrom-detect/try-usb=true without quotes because that's what i think is right. When I press TAB, there already is a text saying : /ubnkern initrd=/ubninit vga=788 -- quiet which can be removed. I have tried to both delete the text before the "--" and just inserting cdrom-detect/try-usb=true before it. Any idea of what can be wrong? I would like to do a full system encryption, or as full as it is possible. I dont want to just encrypt my /home folder. Maybe this isn't the easiest way. I use SanDisk usb sticks. I know there is a problem with U3 launcher on some SanDisks, but I never had to remove U3 before from similar disks, and the alternate install does boot up, so I dont think using U3 removal would help me. Any help or indication to an easier way to do this would be appreciated

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• Behaviour Trees with irregular updates

  - by Robominister

  I'm interested in behaviour trees that aren't iterated every game tick, but every so often. (Edit: the tree could specify how many frames within the main game loop to wait before running its tick function again). Every theoretical implementation I have seen of behaviour trees talks of the tree search being carried out every game update - which seems necessary, because a leaf node (eg a behaviour, like 'return to base') needs to be constantly checked to see if is still running, failed or completed. Can anyone suggest how I might start implementing a tree that isnt run every tick, or point me in the direction of good material specific to this case (I am struggling to find anything)? My thoughts so far: action leaf nodes (when they start) must only push some kind of action object onto a list for an entity, rather than directly calling any code that makes the entity do something. The list of actions for the entity would be run every frame (update any that need to run, pop any that have completed from the list). the return state from a given action must be fed back into the tree, so that when we run the tree iteration again (and reach the same action leaf node - so the tree has so far determined that we ought to still be trying this action) - that the action has completed, or is still running etc. If my actual action code is running from an action list on an entity, then I possibly need to cancel previously running actions in the list - i am thinking that I can just delete the entire stack of queued up actions. I've seen the idea of ActionLists which block lower priority actions when a higher priority one is added, but this seems like very close logic to behaviour trees, and I dont want to be duplicating behaviour. This leaves me with some questions 1) How would I feed the action return state back into the tree? Its obvious I need to store some information relating to 'currently executing actions' on the entity, and check that in the tree tick, but I can't imagine how. 2) Does having a seperate behaviour tree (for deciding behaviour) and action list (for carrying out actual queued up actions) sound like a reasonable approach? 3) Is the approach of updating a behaviour tree irregularly actually used by anyone? It seems like a nice idea for budgeting ai search time when you have a lot of ai entities to process. (Edit) - I am also thinking about storing a single instance of a given behaviour tree in memory, and providing it by reference to any entity that uses it. So any information about what action was last selected for execution on an entity must be stored in a data context relative to the entity (which the tree can check). (I am probably answering my own questions as i go!) I hope I have expressed my questions adequately! Thanks in advance for any help :)

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• PeopleSoft New Design Solves Navigation Problem

  - by Applications User Experience

  Anna Budovsky, User Experience Principal Designer, Applications User Experience In PeopleSoft we strive to improve User Experience on all levels. Simplifying navigation and streamlining access to the most important pages is always an important goal. No one likes to waste time waiting for pages to load and watching a spinning glass going on and on. Those performance-affecting server trips, page-load waits and just-too-many clicks were complained about for a long time. Something had to be done. A few new designs came in PeopleSoft 9.2 helping users to access their everyday work areas easier and faster. For example, Dashboard and Work Center aggregate most accessed information sections on a single page; Related Information allows users to complete transaction-related-research without interrupting a transaction and Secure Search gets users to a specific page directly. Today we’ll talk about the Actions menu. Most PeopleSoft pages are shared between individual products and product lines. It means changing the content on a single page involves Oracle development and quality assurance time for making and testing the changes. In order to streamline the navigation and cut down on accessing PeopleSoft pages one-page-at-a-time, we introduced a new menu design. The new menu allows accessing shared pages without the Oracle development team making any local changes, and it works as an additional one-click-path to specific high-traffic actionable pages. Let’s look at how many steps it took to Change Salary for an employee in HCM 9.1 before: Figure 1. BEFORE: The 6 steps a user would take to Change Salary in PeopleSoft HCM 9.1 In PeopleSoft 9.1 it took 5 steps + page loading time + additional verification time for making sure a correct employee is selected from the table. In PeopleSoft 9.2 it only takes 2 steps. To complete Ad Hoc Change Salary action, the user can start from the HCM Manager's Dashboard, click the Action menu within a table, choose a menu option, and access a correct employee’s details page to take an action. Figure 2. AFTER: The 2 steps a user would take to Change Salary in PeopleSoft HCM 9.2 The new menu is placed on a row level which ensures the user accesses the correct employee’s details page. The Actions menu separates menu options into hierarchical sections which help to scan and access the correct option quickly. The new menu’s small size and its structure enabled users to access high-traffic pages from any page and from any part of the page. No more spinning hourglass, no more multiple pages upload. The flexible design fits anywhere on a page and provides a fast and reliable path to the correct destination within the product. Now users can: Access any target page no matter how far it is buried from the starting point; Reduce navigation and page-load time; Improve productivity and reduce errors. The new menu design is available and widely used in all PeopleSoft 9.2 product lines.

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• algorithm for project euler problem no 18

  - by Valentino Ru

  Problem number 18 from Project Euler's site is as follows: By starting at the top of the triangle below and moving to adjacent numbers on the row below, the maximum total from top to bottom is 23. 3 7 4 2 4 6 8 5 9 3 That is, 3 + 7 + 4 + 9 = 23. Find the maximum total from top to bottom of the triangle below: 75 95 64 17 47 82 18 35 87 10 20 04 82 47 65 19 01 23 75 03 34 88 02 77 73 07 63 67 99 65 04 28 06 16 70 92 41 41 26 56 83 40 80 70 33 41 48 72 33 47 32 37 16 94 29 53 71 44 65 25 43 91 52 97 51 14 70 11 33 28 77 73 17 78 39 68 17 57 91 71 52 38 17 14 91 43 58 50 27 29 48 63 66 04 68 89 53 67 30 73 16 69 87 40 31 04 62 98 27 23 09 70 98 73 93 38 53 60 04 23 NOTE: As there are only 16384 routes, it is possible to solve this problem by trying every route. However, Problem 67, is the same challenge with a triangle containing one-hundred rows; it cannot be solved by brute force, and requires a clever method! ;o) The formulation of this problems does not make clear if the "Traversor" is greedy, meaning that he always choosed the child with be higher value the maximum of every single walkthrough is asked The NOTE says, that it is possible to solve this problem by trying every route. This means to me, that is is also possible without! This leads to my actual question: Assumed that not the greedy one is the max, is there any algorithm that finds the max walkthrough value without trying every route and that doesn't act like the greedy algorithm? I implemented an algorithm in Java, putting the values first in a node structure, then applying the greedy algorithm. The result, however, is cosidered as wrong by Project Euler. sum = 0; void findWay(Node node){ sum += node.value; if(node.nodeLeft != null && node.nodeRight != null){ if(node.nodeLeft.value > node.nodeRight.value){ findWay(node.nodeLeft); }else{ findWay(node.nodeRight); } } }

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• Why would I learn C++11, having known C and C++?

  - by Shahbaz

  I am a programmer in C and C++, although I don't stick to either language and write a mixture of the two. Sometimes having code in classes, possibly with operator overloading, or templates and the oh so great STL is obviously a better way. Sometimes use of a simple C function pointer is much much more readable and clear. So I find beauty and practicality in both languages. I don't want to get into the discussion of "If you mix them and compile with a C++ compiler, it's not a mix anymore, it's all C++" I think we all understand what I mean by mixing them. Also, I don't want to talk about C vs C++, this question is all about C++11. C++11 introduces what I think are significant changes to how C++ works, but it has introduced many special cases that change how different features behave in different circumstances, placing restrictions on multiple inheritance, adding lambda functions, etc. I know that at some point in the future, when you say C++ everyone would assume C++11. Much like when you say C nowadays, you most probably mean C99. That makes me consider learning C++11. After all, if I want to continue writing code in C++, I may at some point need to start using those features simply because my colleagues have. Take C for example. After so many years, there are still many people learning and writing code in C. Why? Because the language is good. What good means is that, it follows many of the rules to create a good programming language. So besides being powerful (which easy or hard, almost all programming languages are), C is regular and has few exceptions, if any. C++11 however, I don't think so. I'm not sure that the changes introduced in C++11 are making the language better. So the question is: Why would I learn C++11? Update: My original question in short was: "I like C++, but the new C++11 doesn't look good because of this and this and this. However, deep down something tells me I need to learn it. So, I asked this question here so that someone would help convince me to learn it." However, the zealous people here can't tolerate pointing out a flaw in their language and were not at all constructive in this manner. After the moderator edited the question, it became more like a "So, how about this new C++11?" which was not at all my question. Therefore, in a day or too I am going to delete this question if no one comes up with an actual convincing argument. P.S. If you are interested in knowing what flaws I was talking about, you can edit my question and see the previous edits.

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• How to Add a Taskbar to the Desktop in Ubuntu 14.04

  - by Lori Kaufman

  If you’ve switched to Ubuntu from Windows, it may take some time to get used to the new and different interface. However, you can easily incorporate a familiar Windows feature, the Taskbar, into Ubuntu to make the transition easier. A tool called Tint2 provides a bar at the bottom of the Ubuntu Desktop that resembles the Windows Taskbar. We will show you how to install it and make it start every time you log into Ubuntu. NOTE: When we say to type something in this article and there are quotes around the text, DO NOT type the quotes, unless we specify otherwise. Press Ctrl + Alt + T to open a Terminal window. To install Tint2, type the following line at the prompt and press Enter. sudo apt-get install tint2 Type your password at the prompt and press Enter. The progress of the installation displays and then a message displays saying how much disk space will be used. When asked if you want to continue, type a “y” and press Enter. When the installation has finished, close the Terminal window by typing “exit” at the prompt and pressing Enter. Click the Search button at the top of the Unity bar. Start typing “startup applications” in the Search box. Items that match what you type start displaying below the Search box. When the Startup Applications tool displays, click the icon to open it. On the Startup Applications Preferences window, click Add. On the Add Startup Program dialog box, enter a name for the startup application. This name displays in the list on the Startup Applications Preferences window. Type “tint2” in the Command edit box, enter a description in the Comment edit box, if desired, and click Add. Tint2 is added as a startup program and will start every time you log into Ubuntu. Click Close to close the Startup Applications Preferences window. Log out and log back in to make the Taskbar available on the desktop. You do not need to reboot the computer for this change to take effect. Now, when you minimize a program, an icon for it displays on the Taskbar at the bottom of the screen, just like the Taskbar in Windows. If you decide that you don’t want the Taskbar to display every time you log into Ubuntu, you can uncheck the Tint2 startup program on the Startup Applications Preferences window. You don’t need to delete it from the list.

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• How can I diagnose/debug "maximum number of clients reached" X errors?

  - by jmtd

  Hi, I'm hitting a problem whereby X prevents processes from creating windows, uttering something like the following into ~/.xsession-errors: cannot open display: :0.0 Maximum number of clients reached Searching around there are lots of examples of people facing this problem, and sometimes people identify which program they are running is using up all the client slots. See e.g. LP 70872 (Firefox), LP 263211 (gnome-screensaver). For what it's worth, I run gnome-terminal, thunderbird, chromium-browser, empathy, tomboy and virtualbox nearly all the time, on top of the normal stuff you get with the GNOME desktop, and occasionally some other bits and pieces. However my question is not "which of my programs is causing this problem" but rather, how can one go about diagnosing this problem? In the above (and other) bugs, forum reports, etc., a number of tools are suggested: xlsclients - lists the client applications for the given display, but I don't think that corresponds to 'X clients' xrestop - a top-style X resources tool, one row per X client. Lots of '' clients, not shown in xlsclients output xwininfo -root -children lists X window objects From what I can gather, the problem might not be too many clients at all, but rather resources kept around in the X server for clients who have long-since detached. But it would also appear that you cannot (easily?) relate X resources back to their client. Can one effectively diagnose this issue once it has started to occur, or is a tedious divide-and-conquer approach for the apps I run the only approach open to me? Update Jan 2011: I think I have resolved this issue. For the benefit of anyone stumbling across this, nautilus and/or compiz or something in that chain of software was segfaulting due to a wallpaper I had. I had chosen an XML file as my wallpaper, which defined a rotating gallery of images. It was hand-made, but based on /usr/share/backgrounds/contest/background-1.xml or similar. Disabling the wallpaper and I have not had a crash since. I'm not marking this as answered yet, since the actual specific problem was not my question, but how to diagnose it was. Unfortunately this was mostly trial-and-error which sucks.

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• Why does my code dividing a 2D array into chunks fail?

  - by Borog

  I have a 2D-Array representing my world. I want to divide this huge thing into smaller chunks to make collision detection easier. I have a Chunk class that consists only of another 2D Array with a specific width and height and I want to iterate through the world, create new Chunks and add them to a list (or maybe a Map with Coordinates as the key; we'll see about that). world = new World(8192, 1024); Integer[][] chunkArray; for(int a = 0; a < map.getHeight() / Chunk.chunkHeight; a++) { for(int b = 0; b < map.getWidth() / Chunk.chunkWidth; b++) { Chunk chunk = new Chunk(); chunkArray = new Integer[Chunk.chunkWidth][Chunk.chunkHeight]; for(int x = Chunk.chunkHeight*a; x < Chunk.chunkHeight*(a+1); x++) { for(int y = Chunk.chunkWidth*b; y < Chunk.chunkWidth*(b+1); y++) { // Yes, the tileMap actually is [height][width] I'll have // to fix that somewhere down the line -.- chunkArray[y][x] = map.getTileMap()[x*a][y*b]; // TODO:Attach to chunk } } chunkList.add(chunk); } } System.out.println(chunkList.size()); The two outer loops get a new chunk in a specific row and column. I do that by dividing the overall size of the map by the chunkSize. The inner loops then fill a new chunkArray and attach it to the chunk. But somehow my maths is broken here. Let's assume the chunkHeight = chunkWidth = 64. For the first Array I want to start at [0][0] and go until [63][63]. For the next I want to start at [64][64] and go until [127][127] and so on. But I get an out of bounds exception and can't figure out why. Any help appreciated! Actually I think I know where the problem lies: chunkArray[y][x] can't work, because y goes from 0-63 just in the first iteration. Afterwards it goes from 64-127, so sure it is out of bounds. Still no nice solution though :/ EDIT: if(y < Chunk.chunkWidth && x < Chunk.chunkHeight) chunkArray[y][x] = map.getTileMap()[y][x]; This works for the first iteration... now I need to get the commonly accepted formula.

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• Help identify the pattern for reacting on updates

  - by Mike

  There's an entity that gets updated from external sources. Update events are at random intervals. And the entity has to be processed once updated. Multiple updates may be multiplexed. In other words there's a need for the most current state of entity to be processed. There's a point of no-return during processing where the current state (and the state is consistent i.e. no partial update is made) of entity is saved somewhere else and processing goes on independently of any arriving updates. Every consequent set of updates has to trigger processing i.e. system should not forget about updates. And for each entity there should be no more than one running processing (before the point of no-return) i.e. the entity state should not be processed more than once. So what I'm looking for is a pattern to cancel current processing before the point of no return or abandon processing results if an update arrives. The main challenge is to minimize race conditions and maintain integrity. The entity sits mainly in database with some files on disk. And the system is in .NET with web-services and message queues. What comes to my mind is a database queue-like table. An arriving update inserts row in that table and the processing is launched. The processing gathers necessary data before the point of no-return and once it reaches this barrier it looks into the queue table and checks whether there're more recent updates for the entity. If there are new updates the processing simply shuts down and its data is discarded. Otherwise the processing data is persisted and it goes beyond the point of no-return. Though it looks like a solution to me it is not quite elegant and I believe this scenario may be supported by some sort of middleware. If I would use message queues for this then there's a need to access the queue API in the point of no-return to check for the existence of new messages. And this approach also lacks elegance. Is there a name for this pattern and an existing solution?

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• Does it make the game more fun when the user is forced to progress thru the levels sequentially rather than letting them pick and play?

  - by BeachRunnerJoe

  Hello. For the first time in my game, I'm stuck with a real design dilemma. I guess that's a good thing ;) I'm building a word puzzle game that has five levels, each with 30 puzzles. Currently, the user has to solve one puzzle at a time before moving to the next. However, I'm finding the user occasionally gets stuck on a puzzle, at which point they can no longer play until they solve it. This is obviously bad because many people will just quit playing the game and delete the app since they get frustrated and can't play any other puzzles until the current puzzle is solved. The only elegant solution I can find to helping the player get unstuck is changing the design of the game to allow the users to pick any puzzle to play at any time. This way, if they get stuck, they can come back to it later and at least they have other puzzles to play in the meantime. It's my opinion, however, that this new flow design doesn't make the game as fun as the original flow design where the player has to complete a puzzle before moving to the next. To me, it's like anything else, when you only have one of something, it's more enjoyable, but when you have 30 of something, it's far less enjoyable. In fact, when I present the user with 30 puzzles to choose from that they need to solve before unlocking the next level, it almost seems as tho I'm making them feel like it's work they have to do. I even had a tester voluntarily tell me that being forced to complete a puzzle before moving to the next is more motivating. My questions are... Do you agree/disagree? Do you have any suggestions for how I can help the player get unstuck? Thanks so much in advance for your thoughts! EDIT: I should mention that I've already considered a few other solutions to helping the user get unstuck, but none of them seem like good ideas. They are... Add more hints: Currently, the user gets two hints per puzzle. If I increase the hint count, it only makes the game more easy and still leaves the possibility of the user getting stuck. Add a "Show Solution" button: This seems like a bad idea because it's my opinion this takes the fun out of the game for many people who would probably otherwise solve the puzzle if they didn't have the quick option to see the solution.

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• SQL 2014 does data the way developers want

  - by Rob Farley

  A post I’ve been meaning to write for a while, good that it fits with this month’s T-SQL Tuesday, hosted by Joey D’Antoni (@jdanton) Ever since I got into databases, I’ve been a fan. I studied Pure Maths at university (as well as Computer Science), and am very comfortable with Set Theory, which undergirds relational database concepts. But I’ve also spent a long time as a developer, and appreciate that that databases don’t exactly fit within the stuff I learned in my first year of uni, particularly the “Algorithms and Data Structures” subject, in which we studied concepts like linked lists. Writing in languages like C, we used pointers to quickly move around data, without a database in sight. Of course, if we had a power failure all this data was lost, as it was only persisted in RAM. Perhaps it’s why I’m a fan of database internals, of indexes, latches, execution plans, and so on – the developer in me wants to be reassured that we’re getting to the data as efficiently as possible. Back when SQL Server 2005 was approaching, one of the big stories was around CLR. Many were saying that T-SQL stored procedures would be a thing of the past because we now had CLR, and that obviously going to be much faster than using the abstracted T-SQL. Around the same time, we were seeing technologies like Linq-to-SQL produce poor T-SQL equivalents, and developers had had a gutful. They wanted to move away from T-SQL, having lost trust in it. I was never one of those developers, because I’d looked under the covers and knew that despite being abstracted, T-SQL was still a good way of getting to data. It worked for me, appealing to both my Set Theory side and my Developer side. CLR hasn’t exactly become the default option for stored procedures, although there are plenty of situations where it can be useful for getting faster performance. SQL Server 2014 is different though, through Hekaton – its In-Memory OLTP environment. When you create a table using Hekaton (that is, a memory-optimized one), the table you create is the kind of thing you’d’ve made as a developer. It creates code in C leveraging structs and pointers and arrays, which it compiles into fast code. When you insert data into it, it creates a new instance of a struct in memory, and adds it to an array. When the insert is committed, a small write is made to the transaction to make sure it’s durable, but none of the locking and latching behaviour that typifies transactional systems is needed. Indexes are done using hashes and using bw-trees (which avoid locking through the use of pointers) and by handling each updates as a delete-and-insert. This is data the way that developers do it when they’re coding for performance – the way I was taught at university before I learned about databases. Being done in C, it compiles to very quick code, and although these tables don’t support every feature that regular SQL tables do, this is still an excellent direction that has been taken. @rob_farley

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• Generate MERGE statements from a table

  - by Bill Graziano

  We have a requirement to build a test environment where certain tables get reset from production every night.  These are mainly lookup tables.  I played around with all kinds of fancy solutions and finally settled on a series of MERGE statements.  And being lazy I didn’t want to write them myself.  The stored procedure below will generate a MERGE statement for the table you pass it.  If you have identity values it populates those properly.  You need to have primary keys on the table for the joins to be generated properly.  The only thing hard coded is the source database.  You’ll need to update that for your environment.  We actually used a linked server in our situation. CREATE PROC dba_GenerateMergeStatement (@table NVARCHAR(128) )ASset nocount on; declare @return int;PRINT '-- ' + @table + ' -------------------------------------------------------------'--PRINT 'SET NOCOUNT ON;--'-- Set the identity insert on for tables with identitiesselect @return = objectproperty(object_id(@table), 'TableHasIdentity')if @return = 1 PRINT 'SET IDENTITY_INSERT [dbo].[' + @table + '] ON; 'declare @sql varchar(max) = ''declare @list varchar(max) = '';SELECT @list = @list + [name] +', 'from sys.columnswhere object_id = object_id(@table)SELECT @list = @list + [name] +', 'from sys.columnswhere object_id = object_id(@table)SELECT @list = @list + 's.' + [name] +', 'from sys.columnswhere object_id = object_id(@table)-- --------------------------------------------------------------------------------PRINT 'MERGE [dbo].[' + @table + '] AS t'PRINT 'USING (SELECT * FROM [source_database].[dbo].[' + @table + ']) as s'-- Get the join columns ----------------------------------------------------------SET @list = ''select @list = @list + 't.[' + c.COLUMN_NAME + '] = s.[' + c.COLUMN_NAME + '] AND 'from INFORMATION_SCHEMA.TABLE_CONSTRAINTS pk , INFORMATION_SCHEMA.KEY_COLUMN_USAGE cwhere pk.TABLE_NAME = @tableand CONSTRAINT_TYPE = 'PRIMARY KEY'and c.TABLE_NAME = pk.TABLE_NAMEand c.CONSTRAINT_NAME = pk.CONSTRAINT_NAMESELECT @list = LEFT(@list, LEN(@list) -3)PRINT 'ON ( ' + @list + ')'-- WHEN MATCHED ------------------------------------------------------------------PRINT 'WHEN MATCHED THEN UPDATE SET'SELECT @list = '';SELECT @list = @list + ' [' + [name] + '] = s.[' + [name] +'],'from sys.columnswhere object_id = object_id(@table)-- don't update primary keysand [name] NOT IN (SELECT [column_name] from INFORMATION_SCHEMA.TABLE_CONSTRAINTS pk , INFORMATION_SCHEMA.KEY_COLUMN_USAGE c where pk.TABLE_NAME = @table and CONSTRAINT_TYPE = 'PRIMARY KEY' and c.TABLE_NAME = pk.TABLE_NAME and c.CONSTRAINT_NAME = pk.CONSTRAINT_NAME)-- and don't update identity columnsand columnproperty(object_id(@table), [name], 'IsIdentity ') = 0 --print @list PRINT left(@list, len(@list) -3 )-- WHEN NOT MATCHED BY TARGET ------------------------------------------------PRINT ' WHEN NOT MATCHED BY TARGET THEN';-- Get the insert listSET @list = ''SELECT @list = @list + '[' + [name] +'], 'from sys.columnswhere object_id = object_id(@table)SELECT @list = LEFT(@list, LEN(@list) - 1)PRINT ' INSERT(' + @list + ')'-- get the values listSET @list = ''SELECT @list = @list + 's.[' +[name] +'], 'from sys.columnswhere object_id = object_id(@table)SELECT @list = LEFT(@list, LEN(@list) - 1)PRINT ' VALUES(' + @list + ')'-- WHEN NOT MATCHED BY SOURCEprint 'WHEN NOT MATCHED BY SOURCE THEN DELETE; 'PRINT ''PRINT 'PRINT ''' + @table + ': '' + CAST(@@ROWCOUNT AS VARCHAR(100));';PRINT ''-- Set the identity insert OFF for tables with identitiesselect @return = objectproperty(object_id(@table), 'TableHasIdentity')if @return = 1 PRINT 'SET IDENTITY_INSERT [dbo].[' + @table + '] OFF; 'PRINT ''PRINT 'GO'PRINT '';

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