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  • SQL SERVER – Beginning of SQL Server Architecture – Terminology – Guest Post

    - by pinaldave
    SQL Server Architecture is a very deep subject. Covering it in a single post is an almost impossible task. However, this subject is very popular topic among beginners and advanced users.  I have requested my friend Anil Kumar who is expert in SQL Domain to help me write  a simple post about Beginning SQL Server Architecture. As stated earlier this subject is very deep subject and in this first article series he has covered basic terminologies. In future article he will explore the subject further down. Anil Kumar Yadav is Trainer, SQL Domain, Koenig Solutions. Koenig is a premier IT training firm that provides several IT certifications, such as Oracle 11g, Server+, RHCA, SQL Server Training, Prince2 Foundation etc. In this Article we will discuss about MS SQL Server architecture. The major components of SQL Server are: Relational Engine Storage Engine SQL OS Now we will discuss and understand each one of them. 1) Relational Engine: Also called as the query processor, Relational Engine includes the components of SQL Server that determine what your query exactly needs to do and the best way to do it. It manages the execution of queries as it requests data from the storage engine and processes the results returned. Different Tasks of Relational Engine: Query Processing Memory Management Thread and Task Management Buffer Management Distributed Query Processing 2) Storage Engine: Storage Engine is responsible for storage and retrieval of the data on to the storage system (Disk, SAN etc.). to understand more, let’s focus on the following diagram. When we talk about any database in SQL server, there are 2 types of files that are created at the disk level – Data file and Log file. Data file physically stores the data in data pages. Log files that are also known as write ahead logs, are used for storing transactions performed on the database. Let’s understand data file and log file in more details: Data File: Data File stores data in the form of Data Page (8KB) and these data pages are logically organized in extents. Extents: Extents are logical units in the database. They are a combination of 8 data pages i.e. 64 KB forms an extent. Extents can be of two types, Mixed and Uniform. Mixed extents hold different types of pages like index, System, Object data etc. On the other hand, Uniform extents are dedicated to only one type. Pages: As we should know what type of data pages can be stored in SQL Server, below mentioned are some of them: Data Page: It holds the data entered by the user but not the data which is of type text, ntext, nvarchar(max), varchar(max), varbinary(max), image and xml data. Index: It stores the index entries. Text/Image: It stores LOB ( Large Object data) like text, ntext, varchar(max), nvarchar(max),  varbinary(max), image and xml data. GAM & SGAM (Global Allocation Map & Shared Global Allocation Map): They are used for saving information related to the allocation of extents. PFS (Page Free Space): Information related to page allocation and unused space available on pages. IAM (Index Allocation Map): Information pertaining to extents that are used by a table or index per allocation unit. BCM (Bulk Changed Map): Keeps information about the extents changed in a Bulk Operation. DCM (Differential Change Map): This is the information of extents that have modified since the last BACKUP DATABASE statement as per allocation unit. Log File: It also known as write ahead log. It stores modification to the database (DML and DDL). Sufficient information is logged to be able to: Roll back transactions if requested Recover the database in case of failure Write Ahead Logging is used to create log entries Transaction logs are written in chronological order in a circular way Truncation policy for logs is based on the recovery model SQL OS: This lies between the host machine (Windows OS) and SQL Server. All the activities performed on database engine are taken care of by SQL OS. It is a highly configurable operating system with powerful API (application programming interface), enabling automatic locality and advanced parallelism. SQL OS provides various operating system services, such as memory management deals with buffer pool, log buffer and deadlock detection using the blocking and locking structure. Other services include exception handling, hosting for external components like Common Language Runtime, CLR etc. I guess this brief article gives you an idea about the various terminologies used related to SQL Server Architecture. In future articles we will explore them further. Guest Author  The author of the article is Anil Kumar Yadav is Trainer, SQL Domain, Koenig Solutions. Koenig is a premier IT training firm that provides several IT certifications, such as Oracle 11g, Server+, RHCA, SQL Server Training, Prince2 Foundation etc. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Security, SQL Server, SQL Tips and Tricks, SQL Training, T SQL, Technology

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  • Speaking at PASS 2012… Exciting and Scary… As usual…

    - by drsql
    Edit: As I reread this, I felt I should clarify.. As usual refers mostly to the "Scary" part. I have a lot of stage fright that I have to work through. And it is always exciting to be picked. I have been selected this year at the PASS Summit 2012 to do two sessions, and they are both going to be interesting. Pre-Con: Relational Database Design Workshop - Abstract Triggers: Born Evil or Misunderstood? - Abstract The pre-con session entitled Relational Database Design Workshop will be (at least) the...(read more)

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  • What's a good scheme for multi-user database synchronization?

    - by Mason Wheeler
    I'm working on a system to allow multiple users to collaborate on an online project. Everything is fairly straightforward, except for keeping the users in sync. Each user has their own local copy of the project database, which allows them to make changes and test things out, and then send the updates to the central server. But this runs into the classic synchronization question: how do you keep two users from editing the same thing and stomping each other's work? I've got an idea that should work, but I wonder if there's a simpler way to do it. Here's the basic concept: All project data is stored in a relational database. Each row in the database has an owner. If the current user is not the owner, he can read but not write that row. (This is enforced client-side.) The user can send a request to the server to take ownership of a row, which will be granted if the server's copy says that the current owner is NULL, or to release ownership when they're done with it. It is not possible to release ownership without committing changes to the server. It is not possible to commit changes to the server without having first downloaded all outstanding changes to the server. When any changes are made to rows you own, a trigger marks that row as Dirty. When you commit changes, the database is scanned for all Dirty rows in all tables, and the data is serialized into an update file, which is posted to the server, and all rows are marked Clean. The server applies the updates on its end, and keeps the file around. When other users download changes, the server sends them the update files that they haven't already received. So, essentially this is a reinvention of version control on a relational database. (Sort of.) As long as taking ownership and applying updates to the server are guaranteed atomic changes, and the server verifies that some smart-aleck user didn't edit their local database so they could send an update for a row they don't have ownership of, it should be guaranteed to be correct, and with no need to worry about merges and merge conflicts. (I think.) Can anyone think of any problems with this scheme, or ways to do it better? (And no, "build [insert VCS here] into your project" is not what I'm looking for. I've thought of that already. VCSs work well with text, and not so well with other file formats, such as relational databases.)

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  • NoSQL is not about object databases

    NoSQL as a movement is an interesting beast. I kinda like that its negatively defined (I happen to belong myself to at least one other such a-community). Its not in its roots about proposing one specific new silver bullet to kill an old problem. its about challenging the consensus. Actually, blindly and systematically replacing relational databases with object databases would just replace one set of issues with another. No, the point is to recognize that relational databases are not a universal...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Plan Operator Tuesday round-up

    - by Rob Farley
    Eighteen posts for T-SQL Tuesday #43 this month, discussing Plan Operators. I put them together and made the following clickable plan. It’s 1000px wide, so I hope you have a monitor wide enough. Let me explain this plan for you (people’s names are the links to the articles on their blogs – the same links as in the plan above). It was clearly a SELECT statement. Wayne Sheffield (@dbawayne) wrote about that, so we start with a SELECT physical operator, leveraging the logical operator Wayne Sheffield. The SELECT operator calls the Paul White operator, discussed by Jason Brimhall (@sqlrnnr) in his post. The Paul White operator is quite remarkable, and can consume three streams of data. Let’s look at those streams. The first pulls data from a Table Scan – Boris Hristov (@borishristov)’s post – using parallel threads (Bradley Ball – @sqlballs) that pull the data eagerly through a Table Spool (Oliver Asmus – @oliverasmus). A scalar operation is also performed on it, thanks to Jeffrey Verheul (@devjef)’s Compute Scalar operator. The second stream of data applies Evil (I figured that must mean a procedural TVF, but could’ve been anything), courtesy of Jason Strate (@stratesql). It performs this Evil on the merging of parallel streams (Steve Jones – @way0utwest), which suck data out of a Switch (Paul White – @sql_kiwi). This Switch operator is consuming data from up to four lookups, thanks to Kalen Delaney (@sqlqueen), Rick Krueger (@dataogre), Mickey Stuewe (@sqlmickey) and Kathi Kellenberger (@auntkathi). Unfortunately Kathi’s name is a bit long and has been truncated, just like in real plans. The last stream performs a join of two others via a Nested Loop (Matan Yungman – @matanyungman). One pulls data from a Spool (my post – @rob_farley) populated from a Table Scan (Jon Morisi). The other applies a catchall operator (the catchall is because Tamera Clark (@tameraclark) didn’t specify any particular operator, and a catchall is what gets shown when SSMS doesn’t know what to show. Surprisingly, it’s showing the yellow one, which is about cursors. Hopefully that’s not what Tamera planned, but anyway...) to the output from an Index Seek operator (Sebastian Meine – @sqlity). Lastly, I think everyone put in 110% effort, so that’s what all the operators cost. That didn’t leave anything for me, unfortunately, but that’s okay. Also, because he decided to use the Paul White operator, Jason Brimhall gets 0%, and his 110% was given to Paul’s Switch operator post. I hope you’ve enjoyed this T-SQL Tuesday, and have learned something extra about Plan Operators. Keep your eye out for next month’s one by watching the Twitter Hashtag #tsql2sday, and why not contribute a post to the party? Big thanks to Adam Machanic as usual for starting all this. @rob_farley

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  • How does a website like Mathway work?

    - by Bob
    I recently found a website called Mathway Basically, it works by allowing you to choose your "level of math" (which it uses to determine what tools it should provide to you) and then allows you to input a math problem which it then solves for you, and gives you detailed solutions (you have to try it, it's really cool). I was wondering how it worked on two levels. First off, how would they parse the math problem (and all the sometimes foreign mathematical operators)? How do they get from text to numbers, variables, and operators? Second, how do they generate the explanations? While you have to pay for the detailed solutions (which are explanations of how they solved the problem), I've seen their preview screenshots, and it looks very detailed. The explanations are given in full, accurate sentences. How would they generate something like that?

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  • Using heavyweight ORM implementation for light based games

    - by Holland
    I'm just about to engulf myself in an MVC-based/Component architecture in C#, using MySQL's connector/Net for the data storage, and probably some NHibernate/FluentNHibernate Object-relational-mapping to map out the data structure. The goal is to build a scalable 2D RPG. Then I think about it...and I can't help but think this seems a little "heavy weight" for a 2D RPG, especially one which, while I plan to incorporate a lot of functionality and entertaining gameplay, may be ported to something like Windows Phone or Android in the future. Yet, on the other hand even a 2-Dimensional RPG can become very complicated, and therefore must incorporate a lot of functionality. While this can be accomplished with text/XML/JSON for data storage, is there a better way? Is something such as Object-Relational-Mapping useful in such an application? So, what do you think? Would you say that there is a place for such technologies? I don't know what to think...

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  • At what size of data does it become beneficial to move from SQL to NoSQL?

    - by wobbily_col
    As a relational database programmer (most of the time), I read articles about how relational databases don't scale, and NoSQL solutions such as MongoDB do. As most of the databases I have developed so far have been small to mid scale, I have never had a problem that hasn't been solved by some indexing, query optimization or schema redesign. What sort of size would I expect to see MySQL struggling with. How many rows? (I know this is going to depend on the application, and type of data stored. the one that got me thing was basically a genetics database, so would have one main table, with 3 or 4 lookup tables. The main table will contain amongst other things, a chromosome reference, and a position coordinate. It will likely get queried for a number of entries between two potions on a chromosome, to see what is stored there).

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  • MySQL for Beginners course - first steps to lowering your Database TCOs

    - by Antoinette O'Sullivan
    Thinking about lowering your Database TCO by using the MySQL Server? Don't miss the chance to get training from the source! With the newly released MySQL for Beginners class, learn how this powerful relational database management system can make your life easier and more fun! This course covers all the basics and will get you on your way, with a solid foundation. This instructor led, hands-on class covers the fundamentals of SQL and relational databases, using MySQL as a teaching tool. Send information about this course release to a friend who might be considering getting started on the world's most popular small footprint database.

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  • Intro to NoSQL with RavenDB

    - by dgreen
    I did a talk on RavenDB back on 9/19/2012. Here was my abstract: "RavenDB is a document database which is gaining popularity in the 'NoSQL' movement. This session will introduce you to some non-relational concepts and describe how they compare/contrast with the relational solutions you're already familiar with. We'll go through the basics of RavenDB and show how easy it is to use from .NET” My next goal is to figure out how to post the slidedeck here (and maybe the code samples if I'm feeling ambitious). Then, the slides can be downloaded for only three easy payments of $39.99. However  for this one time special offer they are currently being given away absolutely FREE with a signup to http://meetup.trinug.org Footnote: I probably shouldn't have to say this, but my last comment about charging for my slidedeck was a joke. I have an odd sense of humor for those who don't already know me :)

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  • Easy QueryBuilder - A User-Friendly Ad-Hoc Advanced Search Solution

    Constructing an easy and powerful QueryBuilder interface becomes more important for complex data grid filtering and accurate reporting services. In this article, I'll discuss how to build a query search engine using ASP.NET AJAX and dynamic SQL. The main goal is to provide an interactive interface to allow users select query attributes, operators, attribute values, and T-SQL operators so that the data context query list can be easily composed and a search engine is invoked.Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Data architecture for event log metrics?

    - by elliot42
    My service has a large ongoing number of user events, and we would like to do things like "count occurrence of event type T since date D." We are trying to make two basic decisions: What to store? Storing every event vs. only storing aggregates (Event log style) log every event and count them later, vs. (Time-series style) store a single aggregated "count of event E for date D" for every day Where to store the data In a relational database (particularly MySQL) In a non-relational (NoSQL) database In flat log files (collected centrally over the network via syslog-ng) What is standard practice / where can I read more about comparing the different types of systems? Additional details: The total event stream is large, potentially hundreds of thousands of entries per day But our current need is only to count certain types of events within it We don't necessarily need real-time access to the raw data or aggregation results IMHO, "log all events to files, crawl them at a later time to filter and aggregate the stream" is a pretty standard UNIX Way, but my Rails-y compatriots seem to think that nothing is real unless it's in MySQL.

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  • Good PHP ORM Library?

    - by sgibbons
    Does anyone know of a good object-relational-mapping library for PHP? I know of PDO/ADO, but they seem to only provide abstraction of differences between database vendors not an actual mapping between the domain model and the relational model. I'm looking for a PHP library that functions similarly to the way Hibernate does for Java/.Net.

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  • Building a regexp to split a string

    - by Kivin
    I'm seeking a solution to splitting a string which contains text in the following format: "abcd efgh 'ijklm no pqrs' tuv" which will produce the following results: ['abcd', 'efgh', 'ijklm no pqrs', 'tuv'] In otherwords, it splits by whitespace unless inside of a single quoted string. I think it could be done with .NET regexps using "Lookaround" operators, particularly balancing operators. I'm not so sure about perl.

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  • How can I split a string by whitespace unless inside of a single quoted string?

    - by Kivin
    I'm seeking a solution to splitting a string which contains text in the following format: "abcd efgh 'ijklm no pqrs' tuv" which will produce the following results: ['abcd', 'efgh', 'ijklm no pqrs', 'tuv'] In other words, it splits by whitespace unless inside of a single quoted string. I think it could be done with .NET regexps using "Lookaround" operators, particularly balancing operators. I'm not so sure about Perl.

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