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  • Working with Temporal Data in SQL Server

    - by Dejan Sarka
    My third Pluralsight course, Working with Temporal Data in SQL Server, is published. I am really proud on the second part of the course, where I discuss optimization of temporal queries. This was a nearly impossible task for decades. First solutions appeared only lately. I present all together six solutions (and one more that is not a solution), and I invented four of them. http://pluralsight.com/training/Courses/TableOfContents/working-with-temporal-data-sql-server

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  • Big Data – Buzz Words: Importance of Relational Database in Big Data World – Day 9 of 21

    - by Pinal Dave
    In yesterday’s blog post we learned what is HDFS. In this article we will take a quick look at the importance of the Relational Database in Big Data world. A Big Question? Here are a few questions I often received since the beginning of the Big Data Series - Does the relational database have no space in the story of the Big Data? Does relational database is no longer relevant as Big Data is evolving? Is relational database not capable to handle Big Data? Is it true that one no longer has to learn about relational data if Big Data is the final destination? Well, every single time when I hear that one person wants to learn about Big Data and is no longer interested in learning about relational database, I find it as a bit far stretched. I am not here to give ambiguous answers of It Depends. I am personally very clear that one who is aspiring to become Big Data Scientist or Big Data Expert they should learn about relational database. NoSQL Movement The reason for the NoSQL Movement in recent time was because of the two important advantages of the NoSQL databases. Performance Flexible Schema In personal experience I have found that when I use NoSQL I have found both of the above listed advantages when I use NoSQL database. There are instances when I found relational database too much restrictive when my data is unstructured as well as they have in the datatype which my Relational Database does not support. It is the same case when I have found that NoSQL solution performing much better than relational databases. I must say that I am a big fan of NoSQL solutions in the recent times but I have also seen occasions and situations where relational database is still perfect fit even though the database is growing increasingly as well have all the symptoms of the big data. Situations in Relational Database Outperforms Adhoc reporting is the one of the most common scenarios where NoSQL is does not have optimal solution. For example reporting queries often needs to aggregate based on the columns which are not indexed as well are built while the report is running, in this kind of scenario NoSQL databases (document database stores, distributed key value stores) database often does not perform well. In the case of the ad-hoc reporting I have often found it is much easier to work with relational databases. SQL is the most popular computer language of all the time. I have been using it for almost over 10 years and I feel that I will be using it for a long time in future. There are plenty of the tools, connectors and awareness of the SQL language in the industry. Pretty much every programming language has a written drivers for the SQL language and most of the developers have learned this language during their school/college time. In many cases, writing query based on SQL is much easier than writing queries in NoSQL supported languages. I believe this is the current situation but in the future this situation can reverse when No SQL query languages are equally popular. ACID (Atomicity Consistency Isolation Durability) – Not all the NoSQL solutions offers ACID compliant language. There are always situations (for example banking transactions, eCommerce shopping carts etc.) where if there is no ACID the operations can be invalid as well database integrity can be at risk. Even though the data volume indeed qualify as a Big Data there are always operations in the application which absolutely needs ACID compliance matured language. The Mixed Bag I have often heard argument that all the big social media sites now a days have moved away from Relational Database. Actually this is not entirely true. While researching about Big Data and Relational Database, I have found that many of the popular social media sites uses Big Data solutions along with Relational Database. Many are using relational databases to deliver the results to end user on the run time and many still uses a relational database as their major backbone. Here are a few examples: Facebook uses MySQL to display the timeline. (Reference Link) Twitter uses MySQL. (Reference Link) Tumblr uses Sharded MySQL (Reference Link) Wikipedia uses MySQL for data storage. (Reference Link) There are many for prominent organizations which are running large scale applications uses relational database along with various Big Data frameworks to satisfy their various business needs. Summary I believe that RDBMS is like a vanilla ice cream. Everybody loves it and everybody has it. NoSQL and other solutions are like chocolate ice cream or custom ice cream – there is a huge base which loves them and wants them but not every ice cream maker can make it just right  for everyone’s taste. No matter how fancy an ice cream store is there is always plain vanilla ice cream available there. Just like the same, there are always cases and situations in the Big Data’s story where traditional relational database is the part of the whole story. In the real world scenarios there will be always the case when there will be need of the relational database concepts and its ideology. It is extremely important to accept relational database as one of the key components of the Big Data instead of treating it as a substandard technology. Ray of Hope – NewSQL In this module we discussed that there are places where we need ACID compliance from our Big Data application and NoSQL will not support that out of box. There is a new termed coined for the application/tool which supports most of the properties of the traditional RDBMS and supports Big Data infrastructure – NewSQL. Tomorrow In tomorrow’s blog post we will discuss about NewSQL. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Big Data, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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  • Theory Of A Weird Thought - Forms Submission

    - by user2738336
    In theory, if you were to open two computers that were perfectly synced together on a website that has a form. This form has fields where say for example the username has to be unique. Assuming both computers have the same information on the form, and in theory let's say that the submit button was pressed at the same time, and that these two computers have the exact same build and internet speed and the same response time from the server, whose information would be submitted to the database and whose information would be denied knowing the username field is unique.

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  • category theory based language

    - by pagoda_5b
    It may sound naive, but is there any programming language, or research thereof, based entirely on category theory? I mean this as opposed to embedding CT concepts as an additional feature (like for Haskell or scala). Would it be too abstract or too complex as an approach, or are there any known reasons that makes it impossible or impractical? I have only a relative understanding of the theory as related to programming, so please give me some explanation if the question doesn't makes sense at all

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  • Is it easy to switch from relational to non-relational databases with Rails?

    - by Tam
    Good day, I have been using Rails/Mysql for the past while but I have been hearing about Cassandra, MongoDB, CouchDB and other document-store DB/Non-relational databases. I'm planning to explore them later as they might be better alternative for scalability. I'm planning to start an application soon. Will it make a different with Rails design if I move from relational to non-relational database? I know Rails migrations are database-agnostic but wasn't sure if moving to non-relational will make difference with design or not.

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  • Color schemes generation - theory and algorithms

    - by daniel.sedlacek
    Hi I will be generating charts and diagrams and I am looking for some theory on color schemes and algorithm examples. Example questions: How to generate complementary or analogous colors? How to generate pastel, cold and warm colors? How to generate any number of random but distinct colors? How to translate all that to the hex triplet (web color)? My implementation will be in AS3 but any examples in metacode are welcome.

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  • Is there really Object-relational impedance mismatch?

    - by user52763
    It is always stated that it is hard to store applications objects in relational databases - the object-relational impedance mismatch - and that is why Document databases are better. However, is there really an impedance mismatch? And object has a key (albeit it may be hidden away by the runtime as a pointer to memory), a set of values, and foreign keys to other objects. Objects are as much made up of tables as it is a document. Neither really fit. I can see a use for databases to model the data into specific shapes for scenarios in the application - e.g. to speed up database lookup and avoid joins, etc., but won't it be better to keep the data as normalized as possible at the core, and transform as required?

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  • Subsumption architecture vs. perceptual control theory

    - by Yasir G.
    I'm a new person to AI field and I have to research and compare 2 different architectures for a thesis I'm writing. Before you scream (homework thread), I've been reading on these 2 topics only to find that I'm confusing myself more.. let me first start with stating briefly what I know so far. Subsumption is based on the fact that targets of a system are different in sophistication, thus that requires them to be added as layers, each layer can suppress (modify) the command of the layers below it, and there are inhibitors to stop signals from execution lets say. PCT stresses on the fact that there are nodes to handle environmental changes (negative feedback), so the inputs coming from an environment go through a comparator node and then an action is generated by that node, HPCT or (Hierarchical PCT) is based on nesting these cycles inside each other so a small cycle to avoid crashing would be nested in a more sophisticated cycle that targets a certain location for example. My questions, am I getting this the right way? am I missing any critical understanding about these 2 models? also any idea where I can find simplified explanations for each theory (so far been struggling trying to understand the papers from Google scholar :< ) /Y

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  • Help to translate SQL query to Relational Algebra

    - by Mestika
    Hi everyone, I'm having some difficulties with translating some queries to Relational Algebra. I've a great book about Database Design and here is a chapter about Relational Algebra but I still seem to have some trouble creating the right one: Thoes queries I've most difficuelt with is these: SELECT COUNT( cs.student_id ) AS counter FROM course c, course_student cs WHERE c.id = cs.course_id AND c.course_name = 'Introduction to Database Design' SELECT COUNT( cs.student_id ) FROM Course c INNER JOIN course_student cs ON c.id = cs.course_id WHERE c.course_name = 'Introduction to Database Design' and SELECT COUNT( * ) FROM student JOIN grade ON student.f_name = "Andreas" AND student.l_name = "Pedersen" AND student.id = grade.student_id I know the notation can be a bit hard to paste into HTML forum, but maybe just use some common name or the Greek name. Thanks in advance Mestika

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  • Operating systems theory -- using minimum number of semaphores

    - by stackuser
    This situation is prone to deadlock of processes in an operating system and I'd like to solve it with the minimum of semaphores. Basically there are three cooperating processes that all read data from the same input device. Each process, when it gets the input device, must read two consecutive data. I want to use mutual exclusion to do this. Semaphores should be used to synchronize: P1: P2: P3: input(a1,a2) input (b1,b2) input(c1,c2) Y=a1+c1 W=b2+c2 Z=a2+b1 Print (X) X=Z-Y+W The declaration and initialization that I think would work here are: semaphore s=1 sa1 = 0, sa2 = 0, sb1 = 0, sb2 = 0, sc1 = 0, sc2 = 0 I'm sure that any kernel programmers that happen on this can knock this out in a minute or 2. Diagram of cooperating Processes and one input device: It seems like P1 and P2 would start something like: wait(s) input (a1/b1, a2/b2) signal(s)

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  • Synonym for "Many-to-Many" relationship (relational databases)

    - by Byron
    What's a synonym for a "many-to-many" relationship? I've finished writing an object-relational mapper but I'm still stumped as to what to name the function that adds that relation. addParent() and addChild() seemed quite logical for the many-to-one/one-to-many and addSuperclass() for one-to-one inheritance, but addManyToMany() would sound quite unintuitive to an object-oriented programmer. addSibling() or addCousin() doesn't really make sense either. Any suggestions? And before you dismiss this as a non-programming question, please remember that consistent naming schemes and encapsulation are pretty integral to programming :)

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  • How do you deal with translating theory into practice?

    - by Mr. Shickadance
    Hello all! Being a computer scientist in a research field I am often tasked with working alongside professionals outside of the software domain (think math people, electrical engineer etc), and then translating their theories and ideas into real-world implementations. I often find it difficult when they present a theoretical problem which appears to be somewhat disconnected from reality. I am not saying that the theory is bogus, only that it is difficult to translate into real-world situations. For example, recently I have been working with software defined radios. We are exploring many different areas, but often the math specialists in my group would present a problem which is heavily grounded in theory (signal processing, physics, whatever). I often struggle at times where it is hard to draw direct parallels between the theory and the real-world implementation that I need to develop. Say we are working on an energy detector, the theory person in my group would say "you need to measure the noise variance with no signal present." This leads me to think "how the hell do I isolate noise from a signal in reality?" There are many examples, but I hope you see where I am going. So, my question is how does one deal with implementation of theoretical concepts when the theory seems detached from reality? Or at least when the connections are not so clear. Or perhaps, the person with the 'theory' may be ignorant of real restrictions? Note: I found this to be a hard question to ask - hopefully you are following me. If you have suggestions on how I could improve it, by all means let me know! Thanks for looking! EDIT: To be a bit more clear, I understand in situations like this that I must learn that specific domain myself to an extent (i.e. signal processing), but I am more concerned with when those theoretical concepts do not appear to be as grounded in practice as one would like.

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  • Are there any formalized/mathematical theories of software testing?

    - by Erik Allik
    Googling "software testing theory" only seems to give theories in the soft sense of the word; I have not been able to find anything that would classify as a theory in the mathematical, information theoretical or some other scientific field's sense. What I'm looking for is something that formalizes what testing is, the notions used, what a test case is, the feasibility of testing something, the practicality of testing something, the extent to which something should be tested, formal definition/explanation of code coverage, etc. UPDATE: Also, I'm not sure, intuitively, about the connection between formal verification and what I asked, but there's clearly some sort of connection.

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  • Why do some programmers think there is a contrast between theory and practice?

    - by Giorgio
    Comparing software engineering with civil engineering, I was surprised to observe a different way of thinking: any civil engineer knows that if you want to build a small hut in the garden you can just get the materials and go build it whereas if you want to build a 10-storey house you need to do quite some maths to be sure that it won't fall apart. In contrast, speaking with some programmers or reading blogs or forums I often find a wide-spread opinion that can be formulated more or less as follows: theory and formal methods are for mathematicians / scientists while programming is more about getting things done. What is normally implied here is that programming is something very practical and that even though formal methods, mathematics, algorithm theory, clean / coherent programming languages, etc, may be interesting topics, they are often not needed if all one wants is to get things done. According to my experience, I would say that while you do not need much theory to put together a 100-line script (the hut), in order to develop a complex application (the 10-storey building) you need a structured design, well-defined methods, a good programming language, good text books where you can look up algorithms, etc. So IMO (the right amount of) theory is one of the tools for getting things done. So my question is why do some programmers think that there is a contrast between theory (formal methods) and practice (getting things done)? Is software engineering (building software) perceived by many as easy compared to, say, civil engineering (building houses)? Or are these two disciplines really different (apart from mission-critical software, software failure is much more acceptable than building failure)?

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  • Relational vs. Dimensional Databases, what's the difference?

    - by grautur
    I'm trying to learn about OLAP and data warehousing, and I'm confused about the difference between relational and dimensional modeling. Is dimensional modeling basically relational modeling, but allowing for redundant/un-normalized data? For example, let's say I have historical sales data on (product, city, # sales). I understand that the following would be a relational point-of-view: Product | City | # Sales Apples, San Francisco, 400 Apples, Boston, 700 Apples, Seattle, 600 Oranges, San Francisco, 550 Oranges, Boston, 500 Oranges, Seattle, 600 While the following is a more dimensional point-of-view: Product | San Francisco | Boston | Seattle Apples, 400, 700, 600 Oranges, 550, 500, 600 But it seems like both points of view would nonetheless be implemented in an identical star schema: Fact table: Product ID, Region ID, # Sales Product dimension: Product ID, Product Name City dimension: City ID, City Name And it's not until you start adding some additional details to each dimension that the differences start popping up. For instance, if you wanted to track regions as well, a relational database would tend to have a separate region table, in order to keep everything normalized: City dimension: City ID, City Name, Region ID Region dimension: Region ID, Region Name, Region Manager, # Regional Stores While a dimensional database would allow for denormalization to keep the region data inside the city dimension, in order to make it easier to slice the data: City dimension: City ID, City Name, Region Name, Region Manager, # Regional Stores Is this correct?

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  • What types of programming require practical category theory?

    - by Alexander Gruber
    Category theory has applications in theoretical computer science and obviously is central to abstract mathematics. I have heard that it also has direct practical applications in programming and software development. What type of programming is practical category theory necessary for? What do programmers use category theory to accomplish? Please note my use of "necessary" and "require" in this post. I realize that in some sense most programmers will benefit from having experience in different types of theories, but I am looking for direct applications where the usage of category theory is essential, i.e. if you didn't know category theory, you probably couldn't do it. Also, I'd like to clarify that by "what type of programming," I am hoping less for a broad answer like "functional programming," and more for specific applications like "writing bank software" or "making operating systems."

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  • Relational Database pioneer Chris Date is giving a seminar 13th/14th May Edinburgh on "SQL and Relat

    - by tonyrogerson
    One of the pioneers of the Relational Database, Chris Date is giving a 2 day seminar in Edinburgh (13th and 14th May 2010) based around his new book "SQL and Relational Theory - How to Write Accurate SQL Code" which if you don't already have I'd say is a must buy. When I first saw this and what he will cover I thought, oh yer - this is going to cost the earth, well it doesn't - its £750 for the two days and there are discounts available for multiple bookings, being a member...(read more)

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  • I want a trivial example of where MongoDB can scale but a relational database will have trouble

    - by Ryan Weir
    I'm just learning to use MongoDB, and when discussing with other programmers would like a quick example of why NoSQL can be a good choice compared to a traditional RDBMS - however the scenarios I come up with and can find online seem pretty contrived. E.g. a blog with lots of traffic could be represented relationally, but will require some performance tuning and joins across tables (assuming full denormalization is being used). Whereas MongoDB would allow direct retrieval from one collection to the same effect. But the response I'm getting from other programmers is "why not just keep it relational and then add some trivial caching later?" Does anybody have a less contrived example where MongoDB will really shine and a relational db will fall over much quicker? The smaller the project/system the better, because it leaves less room for disagreement. Something along the lines of the complexity of the blog example would be really useful. Thanks.

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  • Advanced search engine or server for relational database [closed]

    - by Pawel
    In my current project we are storing big volume of data in relational database. One of the recent key requirements is to enrich application by adding some advanced search capabilities. In the Project, performance is one of the important factors due to very large tables (10+ milions of records) with parent-children relations (for example: multi-level parent-child relationship, where I am looking for all parents with specific children). The search engine should also be able to check these references for hits. I have found some potential engines on stack overflow, however it looks like that all of them are dedicated rather for text search than relational db and hosted on linux os: lucene Solr Sphinx As I understand some of them use documents as a source of searching, but is it possible or efficient to create programmaticaly documents based on my relational data? As I am not familiar with all of their features/capabilities can anyone please make some recommendations or propose some different solution? To summarize my requirements: framework/engine to search relational database including decendants. support for Microsoft SQL Server can be used in .NET applications preferably hosted on Windows systems Does any of mentioned above are able to solve my problem? do you know any better solution?

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  • relational databases and multicast messages

    - by xRobot
    I have read that relational databases are a terrible way to do multicast messages like twitter. So twitter saves every tweet only one times and then retrieve its in every stream ? or saves every tweet in every users's stream ? I want to know why relational database ( like mysql or postgresql ) doesn't good for twitter-like application.

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  • Why does NUnit ignore datapoints when using generics in a theory

    - by The Chairman
    I'm trying to make use of the TheoryAttribute, introduced in NUnit 2.5. Everything works fine as long as the arguments are of a defined type: [Datapoint] public double[,] Array2X2 = new double[,] { { 1, 0 }, { 0, 1 } }; [Theory] public void TestForArbitraryArray(double[,] array) { // ... } It does not work, when I use generics: [Datapoint] public double[,] Array2X2 = new double[,] { { 1, 0 }, { 0, 1 } }; [Theory] public void TestForArbitraryArray<T>(T[,] array) { // ... } NUnit gives a warning saying No arguments were provided. Why is that?

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  • relational data from xml

    - by Beta033
    Our problem is this, we have a relational database to store objects in tables. As any relational database could, several of these tables have multiple foreign keys pointing to other tables (all pretty normal stuff) We've been trying to identify a solution to allow export of this relational data, ideally, only 1 of the objects in the model, to some sort of file (xml, text, ??). So it wouldn't be simple enough to just export 1 table as data stored in other tables would contribute to the complete model of the object. Something like the following picture: Toward this, i've written a routine to export the structure by following the foreign key paths which exports something similar to the following. <Tables> <TableA PK="1", val1, val2, val3> <TableC PK="1", FK_A="1", Val1, val2, val3> <TableC PK="2", FK_A="1", val1, val2, val3> <TableB PK="1", FK_A="1", FK_C="1", val1, val2, val3> <TableB PK="2", FK_A="1", FK_C="2", val1, val2, val3> <TableD PK="1", FK_B="1", FK_C="1", val1> <TableD PK="2", FK_B="2", FK_C="1", val1> </Tables> However, given this structure, it cannot be placed into a heirarchial format (ie D2 is a child of C1 and B2; and B2 is a child of C2) Which in turn, makes my life very difficult when trying to identify a methodology to reimport (and reKey) these objects. Has anybody done anything like this? how do you do it? are there tools or documentation on how this is best accomplished? Thanks for your help.

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