Search Results

Search found 33492 results on 1340 pages for 'cross database'.

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

Page 25/1340 | < Previous Page | 21 22 23 24 25 26 27 28 29 30 31 32  | Next Page >

  • Database Modelling - Conceptually different entities with near identical fields

    - by Andrew Shepherd
    Suppose you have two sets of conceptual entities: MarketPriceDataSet which has multiple ForwardPriceEntries PoolPriceForecastDataSet which has multiple PoolPriceForecastEntry Both different child objects have near identical fields: ForwardPriceEntry has StartDate EndDate SimulationItemId ForwardPrice MarketPriceDataSetId (foreign key to parent table) PoolPriceForecastEntry has StartDate EndDate SimulationItemId ForecastPoolPrice PoolPriceForecastDataSetId (foreign key to parent table) If I modelled them as separate tables, the only difference would be the foreign key, and the name of the price field. There has been a debate as to whether the two near identical tables should be merged into one. Options I've thought of to model this is: Just keep them as two independent, separate tables Have both sets in the one table with an additional "type" field, and a parent_id equalling a foreign key to either parent table. This would sacrifice referential integrity checks. Have both sets in the one table with an additional "type" field, and create a complicated sequence of joining tables to maintain referential integrity. What do you think I should do, and why?

    Read the article

  • Database design - table relationship question

    - by iama
    I am designing schema for a simple quiz application. It has 2 tables - "Question" and "Answer Choices". Question table has 'question ID', 'question text' and 'answer id' columns. "Answer Choices" table has 'question ID', 'answer ID' and 'answer text' columns. With this simple schema it is obvious that a question can have multiple answer choices & hence the need for the answer choices table. However, a question can have only one correct answer and hence the need for the 'answer ID' in the question table. However, this 'answer ID' column in the question table provides a illusion as though there can be multiple questions for a single answer which is not correct. The other alternative to eliminate this illusion is to have another table just for correct answer that will have just 2 columns namely the question ID and the answer ID with a 1-1 relationship between the two tables. However, I think this is redundant. Any recommendation on how best to design this thereby enforcing the rules that a question can have multiple answer choices but only one correct answer? Many Thanks.

    Read the article

  • Generic version control strategy for select table data within a heavily normalized database

    - by leppie
    Hi Sorry for the long winded title, but the requirement/problem is rather specific. With reference to the following sample (but very simplified) structure (in psuedo SQL), I hope to explain it a bit better. TABLE StructureName { Id GUID PK, Name varchar(50) NOT NULL } TABLE Structure { Id GUID PK, ParentId GUID (FK to Structure), NameId GUID (FK to StructureName) NOT NULL } TABLE Something { Id GUID PK, RootStructureId GUID (FK to Structure) NOT NULL } As one can see, Structure is a simple tree structure (not worried about ordering of children for the problem). StructureName is a simplification of a translation system. Finally 'Something' is simply something referencing the tree's root structure. This is just one of many tables that need to be versioned, but this one serves as a good example for most cases. There is a requirement to version to any changes to the name and/or the tree 'layout' of the Structure table. Previous versions should always be available. There seems to be a few possibilities to tackle this issue, like copying the entire structure, but most approaches causes one to 'loose' referential integrity. Example if one followed this approach, one would have to make a duplicate of the 'Something' record, given that the root structure will be a new record, and have a new ID. Other avenues of possible solutions are looking into how Wiki's handle this or go a lot further and look how proper version control systems work. Currently, I feel a bit clueless how to proceed on this in a generic way. Any ideas will be greatly appreciated. Thanks leppie

    Read the article

  • Naming of boolean column in database table

    - by Space Cracker
    I have 'Service' table and the following column description as below Is User Verification Required for service ? Is User's Email Activation Required for the service ? Is User's Mobile Activation required for the service ? I Hesitate in naming these columns as below IsVerificationRequired IsEmailActivationRequired IsMobileActivationRequired or RequireVerification RequireEmailActivation RequireMobileActivation I can't determined which way is the best .So, Is one of the above suggested name is the best or is there other better ones ?

    Read the article

  • Upgrading from SQL2000 database to SQL Express 2008 R2

    - by itwb
    Hi, We have a web application which uses a MSSQL 2000 backend database. We are currently paying a ridiculous amount for Shared Hosting, with the database costs alone costing us $150 per month (MSSQL 100mb extra space is $40 per month). Our database size is 896.38 MB I am looking at getting a Virtual Private Server and upgrading the database to a MSSQL2008 Express database. I am aware that the Express version is limited to a 10GB database (with R2), and is constrained to a single CPU. I have also been offered SQL Server 2008 Web Edition for $19/per month, but I cannot find many details on the difference between Express and Web. Any suggestions here? What I would also like to know is: If we upgrade the database to MSSQL 2008 database, is there any issues with possible data transformations in the future? I.e. Is it possible to download and mount it with SQL Server 2008 Standard edition? I'm more concerned about how to get data in and out of the database through SQL Management tools. Are there any other issues that I might face? Thanks, Mike

    Read the article

  • MySQL root user can't access database

    - by Ed Schofield
    Hi all, We have a MySQL database ('myhours') on a production database server that is accessible to one user ('edsf') only, but not to the root user. The command 'SHOW DATABASES' as the root user does not list the 'myhours' database. The same command as the 'edsf' user lists the database: mysql> SHOW DATABASES; +--------------------+ | Database | +--------------------+ | information_schema | | myhours | +--------------------+ 2 rows in set (0.01 sec) Only the 'edsf' user can access the 'myhours' database with 'USE myhours'. Neither user seems to have permission to grant further permissions for this database. My questions are: Q1. How is it that the root user does not have permission to use the database? How could this have come about? The output of SHOW GRANTS FOR 'root'@'localhost'; looks fine to me: GRANT ALL PRIVILEGES ON *.* TO 'root'@'localhost' IDENTIFIED BY PASSWORD '*xxx' WITH GRANT OPTION Q2. How can I recover this situation to make this database visible to the MySQL root user and grant further permissions on it? Thanks in advance for any help! -- Ed

    Read the article

  • Cross-compiling with OpenSSL for Windows

    - by singpolyma
    I'm trying to compile the oauth-utils http://mir.dnsalias.com/oss/oauth/start for Windows from Ubuntu. I have compiled it on Windows before (a few months back), but wanted to try cross-compiling. I got openssl build using mingw32 ok, and put libssl.a and libcrypto.a in the right place. The linker is now finding the libraries (yay!) but I get the following error: /usr/lib/gcc/i586-mingw32msvc/4.2.1-sjlj/../../../../i586-mingw32msvc/lib/libcrypto.a(rand_win.o):rand_win.c:(.text+0xaac): undefined reference to `_CreateDCA@16' /usr/lib/gcc/i586-mingw32msvc/4.2.1-sjlj/../../../../i586-mingw32msvc/lib/libcrypto.a(rand_win.o):rand_win.c:(.text+0xab9): undefined reference to `_CreateCompatibleDC@4' /usr/lib/gcc/i586-mingw32msvc/4.2.1-sjlj/../../../../i586-mingw32msvc/lib/libcrypto.a(rand_win.o):rand_win.c:(.text+0xacc): undefined reference to `_GetDeviceCaps@8' /usr/lib/gcc/i586-mingw32msvc/4.2.1-sjlj/../../../../i586-mingw32msvc/lib/libcrypto.a(rand_win.o):rand_win.c:(.text+0xadc): undefined reference to `_GetDeviceCaps@8' /usr/lib/gcc/i586-mingw32msvc/4.2.1-sjlj/../../../../i586-mingw32msvc/lib/libcrypto.a(rand_win.o):rand_win.c:(.text+0xaf4): undefined reference to `_CreateCompatibleBitmap@12' /usr/lib/gcc/i586-mingw32msvc/4.2.1-sjlj/../../../../i586-mingw32msvc/lib/libcrypto.a(rand_win.o):rand_win.c:(.text+0xb04): undefined reference to `_SelectObject@8' /usr/lib/gcc/i586-mingw32msvc/4.2.1-sjlj/../../../../i586-mingw32msvc/lib/libcrypto.a(rand_win.o):rand_win.c:(.text+0xb18): undefined reference to `_GetObjectA@12' /usr/lib/gcc/i586-mingw32msvc/4.2.1-sjlj/../../../../i586-mingw32msvc/lib/libcrypto.a(rand_win.o):rand_win.c:(.text+0xb81): undefined reference to `_BitBlt@36' /usr/lib/gcc/i586-mingw32msvc/4.2.1-sjlj/../../../../i586-mingw32msvc/lib/libcrypto.a(rand_win.o):rand_win.c:(.text+0xb8c): undefined reference to `_GetBitmapBits@12' /usr/lib/gcc/i586-mingw32msvc/4.2.1-sjlj/../../../../i586-mingw32msvc/lib/libcrypto.a(rand_win.o):rand_win.c:(.text+0xbe5): undefined reference to `_SelectObject@8' /usr/lib/gcc/i586-mingw32msvc/4.2.1-sjlj/../../../../i586-mingw32msvc/lib/libcrypto.a(rand_win.o):rand_win.c:(.text+0xbec): undefined reference to `_DeleteObject@4' /usr/lib/gcc/i586-mingw32msvc/4.2.1-sjlj/../../../../i586-mingw32msvc/lib/libcrypto.a(rand_win.o):rand_win.c:(.text+0xbf6): undefined reference to `_DeleteDC@4' /usr/lib/gcc/i586-mingw32msvc/4.2.1-sjlj/../../../../i586-mingw32msvc/lib/libcrypto.a(rand_win.o):rand_win.c:(.text+0xc00): undefined reference to `_DeleteDC@4' Any ideas what could be causing this? Thanks.

    Read the article

  • IE History Tracking, IFRAMES, and Cross Domain error...

    - by peiklk
    So here's the deal. We have a Flash application that is running within an HTML file. For one page we call a legacy reporting system in ASP.NET that is within an IFRAME. This page then communicates back to the Flash application using cross-domain scripting (document.domain = "domain" is set in both pages. THIS ALL WORKS. Now the kicker. Flash has history tracking enabled. This loads the history.js file that created a div tag to store page changes so the back and forward buttons work in the browser. Which works for Firefox and Chrome as they create a div tag. HOWEVER In Internet Explorer, history.js creates another IFRAME (instead of a DIV) called ie_historyFrame. When the ScriptResource.axd code attempts to access this with: var frameDoc = this._historyFrame.contentWindow.document; we get an "Access is Denied" error message. ARGH! We've tried getting a handle to this IFRAME and inserting the document.domain code. FAIL. We've tried editing the historytemplate.html file that flex also uses to include document.domain... FAIL. I've tried to edit the underlying ASP.NET page to disable history tracking in the ScriptManager control. FAIL. At my wit's end on this one. We have users who need to use IE to access this site. They are big clients who we cannot tell to just use Firefox. Any suggestions would be greatly appreciated.

    Read the article

  • Issues with cross-domain uploading

    - by meder
    I'm using a django plugin called django-filebrowser which utilizes uploadify. The issue I'm having is that I'm hosting uploadify.swf on a remote static media server, whereas my admin area is on my django server. At first, the browse button wouldn't invoke my browser's upload. I fixed this by modifying the sameScriptAccess to always instead of sameDomain. Now the progress bar doesn't move at all, I probably have to enable some server setting for cross domain file uploading, or most likely actually host a separate upload script on my media server. I thought I could solve this by adding a crossdomain.xml to enable any site at the root of both servers, but that doesn't seem to solve it. $(document).ready(function() { $('#id_file').uploadify({ 'uploader' : 'http://media.site.com:8080/admin/filebrowser/uploadify/uploadify.swf', 'script' : '/admin/filebrowser/upload_file/', 'scriptData' : {'session_key': '...'}, 'checkScript' : '/admin/filebrowser/check_file/', 'cancelImg' : 'http://media.site.com:8080/admin/filebrowser/uploadify/cancel.png', 'auto' : false, 'folder' : '', 'multi' : true, 'fileDesc' : '*.html;*.py;*.js;*.css;*.jpg;*.jpeg;*.gif;*.png;*.tif;*.tiff;*.mp3;*.mp4;*.wav;*.aiff;*.midi;*.m4p;*.mov;*.wmv;*.mpeg;*.mpg;*.avi;*.rm;*.pdf;*.doc;*.rtf;*.txt;*.xls;*.csv;', 'fileExt' : '*.html;*.py;*.js;*.css;*.jpg;*.jpeg;*.gif;*.png;*.tif;*.tiff;*.mp3;*.mp4;*.wav;*.aiff;*.midi;*.m4p;*.mov;*.wmv;*.mpeg;*.mpg;*.avi;*.rm;*.pdf;*.doc;*.rtf;*.txt;*.xls;*.csv;', 'sizeLimit' : 10485760, 'scriptAccess' : 'always', //'scriptAccess' : 'sameDomain', 'queueSizeLimit' : 50, 'simUploadLimit' : 1, 'width' : 300, 'height' : 30, 'hideButton' : false, 'wmode' : 'transparent', translations : { browseButton: 'BROWSE', error: 'An Error occured', completed: 'Completed', replaceFile: 'Do you want to replace the file', unitKb: 'KB', unitMb: 'MB' } }); $('input:submit').click(function(){ $('#id_file').uploadifyUpload(); return false; }); }); The page I'm viewing this on is http://site.com/admin/filebrowser/browse on port 80.

    Read the article

  • Cross-platform game development: ease of development vs security

    - by alcuadrado
    Hi, I'm a member and contributor of the Argentum Online (AO) community, the first MMORPG from Argentina, which is Free Software; which, although it's not 3D, it's really addictive and has some dozens of thousands of users. Really unluckily AO was developed in Visual Basic (yes, you can laugh) but the former community, so imagine, the code not only sucks, it has zero portability. I'm planning, with some friends to rewrite the client, and as a GNU/Linux frantic, want to do it cross-platform. Some other people is doing the same with the server in Java. So my biggest problem is that we would like to use a rapid development language (like Java, Ruby or Python) but the client would be pretty insecure. Ruby/Python version would have all it's code available, and the Java one would be easily decompilable (yes, we have some crackers in the community) We have consider the option to implement the security module in C/C++ as a dynamic library, but it can be replaced with a custom one, so it's not really secure. We are also considering the option of doing the core application in C++ and the GUI in Ruby/Python. But haven't analysed all it's implications yet. But we really don't want to code the entire game in C/C++ as it doesn't need that much performance (the game is played at 18fps on average) and we want to develop it as fast as possible. So what would you choose in my case? Thank you!

    Read the article

  • Google GWT cross-browser support: is it BS ?

    - by Tim
    I developed a browser-deployed full-text search app in FlashBuilder which communicates RESTfully with a remote web-server. The software fits into a tiny niche--it is for use with ancient languages not modern ones, and there's no way I'm going to make any money on it but I did spend a lot of time on it. Now that Apple won't allow Flash on the iPad, I'm looking for a 100% javascript solution and was led to consider GWT. It looked promising, but one of the apps being "showcased" as a stellar example of what can be done with GWT has this disclaimer on their website (names {removed} to protect the potentially innocent) : Your current web browser (Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US) AppleWebKit/532.5 (KHTML, like Gecko) Chrome/4.1.249.1045 Safari/532.5) is not officially supported by {company and product name were here}. If you experience any problems using this site please install either Microsoft Internet Explorer 6+ or Mozilla Firefox 3.5+ before contacting {product name was here} Support. What gives when GWT apps aren't "officially" supported on Chrome? What grade (A, B, C, D, F) would you give to GWT for cross-browser support? For folks who don't get these kinds of letter grades, A is "excellent" and "F" is failure, and "C" is average. Thanks for your opinions.

    Read the article

  • Cross-domain templating with Javascript

    - by Husky
    I'm currently building a Javascript library that can be used to easily create embeddable media based on the URL of a media file, and then be controlled using Javascript methods and events (think something like the Flash / Silverlight JW player). Of course, i could simply cat all the html tags from the Javascript library and send that to the browser: function player(url) { document.write('<object type="foo"><param name="something" value="bar">' + <param name="source" value=" + url + '/></object>'); } But i think this is a very ugly practice that tends to create unmanageable code that is unreadable when you review it a few weeks later. So, a templating solution seems to be the way to go. I've been looking to EJS because it loads the templates using AJAX, so you can manage your templates in separate file instead of directly on the HTML page. There's one 'gotcha' with that: my library needs to be completely cross-domain: the library itself could be located on foo.com while the serving site could be located on bar.com. So if bar.com would want to add a media player using the library it needs to do an AJAX call to a template located on foo.com, which won't work because of the same-origin policy in browsers. AFAIK, there's no library that uses something like JSONP to read and write templates to get around this problem. Could anyone point me to a solution for this problem?

    Read the article

  • Cross-Platform Camera API

    - by Karim
    Hi, I'm now building a video transforming filter that have to transform video frames in real-time. One of the key requirements of the filter is to have high performance to minimize the number of dropped frames during the transform. Another requirement that is of lower priority but also nice to have is to make it cross-platform (both PC's and Mobile devices). The application is built in C++. Now my question is: is there any API that is more portable and has a similar or better performance characteristics than DirectShow? as DirectShow's portability is only limited to Windows-based devices (PCs and Windows Mobile&CE platforms). Also I've notices that for example using HTC's custom camera API has far better performance than what DirectShow offers. If you want to check this, try to build a filter in DirectShow that will multiply each color by 2 and render that in real-time from camera on the screen. Then do the same with HTC's API. There is almost 4-5x performance boost with vendor's specific API. So it'd be very nice if the library used the device-specific implementation of the driver, as performance is critical when doing this transforms on a mobile device (which is about ~500 MHz).

    Read the article

  • Cross-domain data access in JavaScript

    - by vit
    We have an ASP.Net application hosted on our network and exposed to a specific client. This client wants to be able to import data from their own server into our application. The data is retrieved with an HTTP request and is CSV formatted. The problem is that they do not want to expose their server to our network and are requesting the import to be done on the client side (all clients are from the same network as their server). So, what needs to be done is: They request an import page from our server The client script on the page issues a request to their server to get CSV formatted data The data is sent back to our application This is not a challenge when both servers are on the same domain: a simple hidden iframe or something similar will do the trick, but here what I'm getting is a cross-domain "access denied" error. They also refuse to change the data format to return JSON or XML formatted data. What I tried and learned so far is: Hidden iframe -- "access denied" XMLHttpRequest -- behaviour depends on the browser security settings: may work, may work while nagging a user with security warnings, or may not work at all Dynamic script tags -- would have worked if they could have returned data in JSON format IE client data binding -- the same "access denied" error Is there anything else I can try before giving up and saying that it will not be possible without exposing their server to our application, changing their data format or changing their browser security settings? (DNS trick is not an option, by the way).

    Read the article

  • Cross-platform iteration of Unicode string

    - by kizzx2
    I want to iterate each character of a Unicode string, treating each surrogate pair and combining character sequence as a single unit (one grapheme). Example The text "??????" is comprised of the code points: U+0928, U+092E, U+0938, U+094D, U+0924, U+0947, of which, U+0938 and U+0947 are combining marks. static void Main(string[] args) { const string s = "??????"; Console.WriteLine(s.Length); // Ouptuts "6" var l = 0; var e = System.Globalization.StringInfo.GetTextElementEnumerator(s); while(e.MoveNext()) l++; Console.WriteLine(l); // Outputs "4" } So there we have it in .NET. We also have Win32's CharNextW() #include <Windows.h> #include <iostream> #include <string> int main() { const wchar_t * s = L"??????"; std::cout << std::wstring(s).length() << std::endl; // Gives "6" int l = 0; while(CharNextW(s) != s) { s = CharNextW(s); ++l; } std::cout << l << std::endl; // Gives "4" return 0; } Question Both ways I know of are specific to Microsoft. Are there portable ways to do it? I heard about ICU but I couldn't find something related quickly (UnicodeString(s).length() still gives 6). Would be an acceptable answer to point to the related function/module in ICU. C++ doesn't have a notion of Unicode, so a lightweight cross-platform library for dealing with these issues would make an acceptable answer.

    Read the article

  • Cross-platform general purpose C++ RPC library

    - by iUm
    Here's the task: Imagine, we have an applications and a plug-in for it (dynamic library). Interface between the application and the plug-in is completely defined. Now I need to run the application and the plug-in on different computers. I wrote a stub for the plug-in on a computer where the real applications is running. And the application loads it and calls its functions like if it were a native plug-in. On the other computer there's a stub instead of the real application, which loads the native plug-in. Now I need to organize RPCs between my stubs over the network, regardless the very transport. Usually, it's not difficult. But there're some restrictions: Application-plug-in interaction can be reenterable (e.g. application calls f1() from plug-in, in f1() plug-in calls g1() from application, in g1() application calls f2() from plug-in and so on...) Any such reenteration should be executed exactly by the same thread, which started the sequence Where can I find a cross-platform C++ RPC library with such features?

    Read the article

  • Cross Platform C library for GUI Apps?

    - by Moshe
    Free of charge, simple to learn/use, Cross Platform C library for GUI Apps? Am I looking for Qt? Bonus question: Can I develop with the said library/toolkit on Mac then recompile on PC/Linux? Super Bonus Question: Link to tutorial and/or download of said library. (RE)EDIT: The truth is that I'm in the process of catching up on the C family (coming from web development - XHTML/PHP/MySQL) to learn iPhone development. I do understand that C is not C++ or ObjectiveC but I want to keep the learning curve as simple as possible. Not to get too off topic, but I am also on the lookout for good starter books and websites. I've found this so far. I'm trying to kill many birds with one stone here. I don understand that there are platform specific extensions, but I will try to avoid those for porting purposes The idea is that I want to write the code on one machine and just compile thrice. (Mac/Win/Linux) If Objective C will compile on Windows and Linux as well as OS X then that's good. If I must use C++, that's also fine. EDIT: Link to QT Please...

    Read the article

  • Cross-platform HTML application options

    - by Charles
    I'd like to develop a stand-alone desktop application targeting Windows (XP through 7) and Mac (Tiger through Snow Leopard), and if possible iPhone and Android. In order to make it all work with as much common code as possible (and because it's the only thing I'm good at), I'd like to handle the main logic with HTML and JS. Using Adobe AIR is a possibility. And I think I can do this with various application wrappers, using .NET for Windows XP, Objective C for iPhone, Java for Android and native "widget" platform support for Mac and Windows Vista & 7 (though I'd like to keep the widget in the foreground, so the Mac dashboard isn't ideal). Does anyone have any suggestions on where to start? The two sticking points are: I'll certainly need some form of persistent storage (cookies perhaps) to keep state between sessions I'll also probably need access to remote data files, so if I use AJAX and the hosting HTML file resides on the device, it will need to be able to do cross-domain requests. I've done this on the iPhone without any problems, but I'd be surprised if this were possible on other platforms. For me, Android and iPhone will be the easiest to handle, and it looks like I can use Adobe AIR to handle the rest. But I wanted to know if there are any other alternatives. Does anyone have any suggesions?

    Read the article

  • Easy to use cross-platform 3D engines for C++ game development?

    - by davr
    I want to try my hand at writing a 3D game. However I don't want to start at such a low level of drawing individual triangles and writing my own 3D object loader and so on. I've heard of things like Irrlicht, Crystal Space 3D, and Cafu, but I don't have any experience with any of them. I'm looking for suggestions from people who have experience with these or other engines on which ones are well written, and are easy to get started using, without having to learn a ton of 3D math theory and how GPU's work internally.

    Read the article

  • Getting started with Oracle Database In-Memory Part III - Querying The IM Column Store

    - by Maria Colgan
    In my previous blog posts, I described how to install, enable, and populate the In-Memory column store (IM column store). This weeks post focuses on how data is accessed within the IM column store. Let’s take a simple query “What is the most expensive air-mail order we have received to date?” SELECT Max(lo_ordtotalprice) most_expensive_order FROM lineorderWHERE  lo_shipmode = 5; The LINEORDER table has been populated into the IM column store and since we have no alternative access paths (indexes or views) the execution plan for this query is a full table scan of the LINEORDER table. You will notice that the execution plan has a new set of keywords “IN MEMORY" in the access method description in the Operation column. These keywords indicate that the LINEORDER table has been marked for INMEMORY and we may use the IM column store in this query. What do I mean by “may use”? There are a small number of cases were we won’t use the IM column store even though the object has been marked INMEMORY. This is similar to how the keyword STORAGE is used on Exadata environments. You can confirm that the IM column store was actually used by examining the session level statistics, but more on that later. For now let's focus on how the data is accessed in the IM column store and why it’s faster to access the data in the new column format, for analytical queries, rather than the buffer cache. There are four main reasons why accessing the data in the IM column store is more efficient. 1. Access only the column data needed The IM column store only has to scan two columns – lo_shipmode and lo_ordtotalprice – to execute this query while the traditional row store or buffer cache has to scan all of the columns in each row of the LINEORDER table until it reaches both the lo_shipmode and the lo_ordtotalprice column. 2. Scan and filter data in it's compressed format When data is populated into the IM column it is automatically compressed using a new set of compression algorithms that allow WHERE clause predicates to be applied against the compressed formats. This means the volume of data scanned in the IM column store for our query will be far less than the same query in the buffer cache where it will scan the data in its uncompressed form, which could be 20X larger. 3. Prune out any unnecessary data within each column The fastest read you can execute is the read you don’t do. In the IM column store a further reduction in the amount of data accessed is possible due to the In-Memory Storage Indexes(IM storage indexes) that are automatically created and maintained on each of the columns in the IM column store. IM storage indexes allow data pruning to occur based on the filter predicates supplied in a SQL statement. An IM storage index keeps track of minimum and maximum values for each column in each of the In-Memory Compression Unit (IMCU). In our query the WHERE clause predicate is on the lo_shipmode column. The IM storage index on the lo_shipdate column is examined to determine if our specified column value 5 exist in any IMCU by comparing the value 5 to the minimum and maximum values maintained in the Storage Index. If the value 5 is outside the minimum and maximum range for an IMCU, the scan of that IMCU is avoided. For the IMCUs where the value 5 does fall within the min, max range, an additional level of data pruning is possible via the metadata dictionary created when dictionary-based compression is used on IMCU. The dictionary contains a list of the unique column values within the IMCU. Since we have an equality predicate we can easily determine if 5 is one of the distinct column values or not. The combination of the IM storage index and dictionary based pruning, enables us to only scan the necessary IMCUs. 4. Use SIMD to apply filter predicates For the IMCU that need to be scanned Oracle takes advantage of SIMD vector processing (Single Instruction processing Multiple Data values). Instead of evaluating each entry in the column one at a time, SIMD vector processing allows a set of column values to be evaluated together in a single CPU instruction. The column format used in the IM column store has been specifically designed to maximize the number of column entries that can be loaded into the vector registers on the CPU and evaluated in a single CPU instruction. SIMD vector processing enables the Oracle Database In-Memory to scan billion of rows per second per core versus the millions of rows per second per core scan rate that can be achieved in the buffer cache. I mentioned earlier in this post that in order to confirm the IM column store was used; we need to examine the session level statistics. You can monitor the session level statistics by querying the performance views v$mystat and v$statname. All of the statistics related to the In-Memory Column Store begin with IM. You can see the full list of these statistics by typing: display_name format a30 SELECT display_name FROM v$statname WHERE  display_name LIKE 'IM%'; If we check the session statistics after we execute our query the results would be as follow; SELECT Max(lo_ordtotalprice) most_expensive_order FROM lineorderWHERE lo_shipmode = 5; SELECT display_name FROM v$statname WHERE  display_name IN ('IM scan CUs columns accessed',                        'IM scan segments minmax eligible',                        'IM scan CUs pruned'); As you can see, only 2 IMCUs were accessed during the scan as the majority of the IMCUs (44) in the LINEORDER table were pruned out thanks to the storage index on the lo_shipmode column. In next weeks post I will describe how you can control which queries use the IM column store and which don't. +Maria Colgan

    Read the article

  • What could be a reason for cross-platform server applications developer to make his app work in multiple processes?

    - by Kabumbus
    So we consider a server app development - heavily loaded with messing with big data streams.An app will be running on one powerful server. a server app shall be developed in form of crossplatform application - so to work on Windows, Mac OS X and Linux. So same code many platforms for standing alone server architecture. We wonder what benefits does distributing applications not only over threads but over processes as wall would bring to programmers and to server end users and why? Some people sad to me that even having 48 cores, 4 process threads would be shared via OS throe all cores... is it true BTW?

    Read the article

  • How can I get cross-browser consistent behavior for TR heights within a table with a set height? [migrated]

    - by Dan
    I have an arbitrary number of tables with an arbitrary number of rows in each, and all tables are the same height. My initial approach was to just set the overall height of the table and hope the rows were smart enough to distribute themselves appropriately. That's not the case. I have 4 different behaviors going on with 4 browsers, but I need them to all render at the very least in a similar way. Safari & Chrome (WebKit): All rows are equal height, creating scroll bars as needed and fitting within table height. Firefox: All rows are the height necessary to fit their content, with the remaining rows overflowing out of the table. Additionally, If the content of the rows does not take up all of the height, only the part of the table with content in it takes the background (though it seems, through use of Firebug, that the actual table [and TR] extend to the bottom of the proper table height). IE: All rows are the height necessary to fit their content, with the remaining rows overflowing out of the table. Obviously this only includes one version of each browser and additional variation would likely appear with more being tested. Ideally, a solution where the browser renders TRs with less content smaller than those with larger content, while still using scrolling within the variable height TRs when the overall height of the table is not enough would be optimum. I could potentially see a solution to achieve that with JS, but can it be done with CSS? Or, if not, can the behavior that WebKit displays be made to work across the browsers? Thanks! PS: Example can be found here.

    Read the article

facebook twitter digg google delicious technorati stumbleupon myspace wordpress linkedin gmail igoogle windows live tumblr viadeo yahoo buzz yahoo mail yahoo bookmarks favorites email print

< Previous Page | 21 22 23 24 25 26 27 28 29 30 31 32  | Next Page >