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  • Suggest Cassandra data model for an existing schema

    - by Andriy Bohdan
    Hello guys! I hope there's someone who can help me suggest a suitable data model to be implemented using nosql database Apache Cassandra. More of than I need it to work under high loads and large amounts of data. Simplified I have 3 types of objects: Product Tag ProductTag Product: key - string key name - string .... - some other fields Tag: key - string key name - unique tag words ProductTag: product_key - foreign key referring to product tag_key - foreign key referring to tag rating - this is rating of tag for this product Each product may have 0 or many tags. Tag may be assigned to 1 or many products. Means relation between products and tags is many-to-many in terms of relational databases. Value of "rating" is updated "very" often. I need to be run the following queries Select objects by keys Select tags for product ordered by rating Select products by tag order by rating Update rating by product_key and tag_key The most important is to make these queries really fast on large amounts of data, considering that rating is constantly updated.

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  • Rspec-rails doesn't seem to find my models

    - by sa125
    Hi - I'm trying out rspec, and immediately hit a wall when it doesn't seem to load db records I know exist. Here's my fairly simple spec (no tests yet). require File.expand_path(File.dirname(__FILE__) + '../spec_helper') describe SomeModel do before :each do @user1 = User.find(1) @user2 = User.find(2) end it "should do something fancy" end I get an ActiveRecord::RecordNotFound exception, saying it couldn't find User w/ ID=1 or ID=2, which I know for a fact exist. I set both test and development databases to point to the same schema in database.yml, so this shouldn't be database mixup. I also ran script/generate rspec after installing the gems (rspec, rspec-rails), and gem.config both environment.rb and test.rb. Any idea what I'm missing? thanks. EDIT Seems I was running the tests with rake spec:models, which emptied the db and thus no records were found. When I used % spec spec/models/some_model_spec.rb, everything worked as expected.

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  • Using pyodbc to insert rows into a MS Access MDB, how do I escape the paramaters?

    - by MDBGuy
    Hi, I'm using pyodbc to talk to a legacy Access 2000 .mdb file. I've got a cursor, and am trying to execute this: c.execute("INSERT INTO [Accounts] ([Name], [TypeID], [StatusID], [AccountCat], [id]) VALUES (?, ?, ?, ?, ?)", [u'test', 20, 10, 4, 2]) However, doing so results in pyodbc.Error: ('HYC00', '[HYC00] [Microsoft][ODBC Microsoft Access Driver]Optional feature not implemented (106) (SQLBindParameter)') I understand I can simply change the question marks to the literal values, but in my experience proper escaping of strings across databases is... not pretty. PHP and mysql team up to bring mysql_real_escape_string and friends, but I can't seem to find pyodbc's function for escaping values. If you could let me know what the recommended way of inserting this data (from python) is, that'd be very helpful. Alternatively, if you have a python function to escape the odbc strings, that would also be great. Thanks for the help.

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  • What is an Ontology (Database?) ?

    - by Robert Gould
    I was just reading this article and it mentions that some organization had an Ontology as(?) their database(?) layer, and that the decision to do this was bad. Problem is I hadn't heard about this before, so I can't understand why it's bad. So I tried googling about databases and ontology, and came about quite a few pdfs from 2006 that we're full of incomprehensible content (for my mind). I read a few of these and at this point still have absolutely no idea what they are talking about. My current impression is that it was some crazy fad of 2006 that some academics were trying to sell us, but failed miserably due to the wording of their ideas. But I'm still curious if anyone actually knows what this is actually all about.

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  • Detect if a table contains a column in Android/sqlite

    - by sandis
    So I have an app on the market, and with an update I want to add some columns to the database. No problems so far. But I want to detect if the database in use is missing these columns, and add them if this is the case. I need this to be done dynamically and not just after the update to the new version, because the application is supposed to still be able to import older databases. Normally I would be able to use the PRAGMA query, but Im not sure how to do this with Android. I cant use execSQL since it is a query, and I cant figure out how to use PRAGMA with the query()-function. Ofcourse I could just catch exceptions and then add the column, or always add the columns to each table before I start to work with it, but that is not a neat solution. Cheers,

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  • How hard is it to modify the Django Models?

    - by alex
    I am doing geolocation, and Django does not have a PointField. So, I am forced to writing in RAW SQL. GeoDjango, the Django library, does not support the following query for MYSQL databases (can someone verify that for me?) cursor.execute("SELECT id FROM l_tag WHERE\ (GLength(LineStringFromWKB(LineString(asbinary(utm),asbinary(PointFromWKB(point(%s, %s)))))) < %s + accuracy + %s)\ I don't nkow why GeoDjango library cannot do this in MYSQL database. I hate writing RAW SQL for calculating distances between two points. Is there a way I can create my own library for Django that can handle this? If so, how hard is it?

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  • TFS Database Edition doesn't seem to Script Logins

    - by Jaco Pretorius
    I'm trying to put all our databases in TFS. For this purpose we're using TFS Database edition - I've seen some of the other Dev teams use it and it seems pretty good. Problem is that it doesn't seem to script the logins - the users are linked to logins which now break due to the logins not being scripted. As far as I can tell I can't get around this - the Schemas need the users which in turn need the logins. How do you handle logins in TFS Database Projects? This is SQL Server 2008.

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  • Wanting a simple overview on how to connect to a SQLite database in Cocoa/Objective-C

    - by Jesse
    Hi, everyone. I've been experimenting with Cocoa and Objective-C programming on the Mac for a few months now, and I am wanting to start developing applications that manage large amounts of data. The trouble is, I'm not really sure where to start with databases. I have a good background in Java programming with SQLite. I've read a bit about CoreData and I haven't been able to find any good resources for just manually connecting to the database. I'm looking for recommendations. Should I try CoreData, and if so, can anyone recommend a good tutorial for someone new to the language? Or, should I try to manually connect and query an SQLite database somehow, and, if so, any tutorials? Any help would be greatly appreciated! Thanks!

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  • Autocomplete and Dynamic Parameter Passing

    - by abcParsing
    The code below works fine using jQuery UI 1.8 and jQuery 1.4.2 $("#sid_entry_box").autocomplete( {source:"autocomplete_sid.php?database="+database_name, minLength:4, delay:1000, enable:true, cacheLength:1 }); The database name is passed as a get parameter of the php call. In this application, I have two databases selected by a radio button. Since jQuery loads and assigns this function when the document is loaded, the database name is whatever was checked at that momemnt. What I really need to pass to the php call is the following: database=$("input[name=rf_database_option]:checked").val(); Is ther ean easy to understand way to be able to pass a dynamic dom value?

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  • ASP.NET MVC TDD with LINQ and SQL database

    - by dean nolan
    I am trying to start a new MVC project with tests and I thought the best way to go would have 2 databases. 1 for testing against and 1 for when I run the app and use it (also test really as it's not production yet). For the test database I was thinking of putting create table scripts and fill data scripts within the test setup method and then deleting all this in the tear down method. I am going to be using Linq to SQL though and I don't think that will allow me to do this? Will I have to just go the ADO route if I want to do it this way? Or should I just use a mock object and store data as an array or something?. Any tips on best practices? How did Jeff go about doing this for StackOveflow?

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  • how to use different oracle character sets in one application

    - by Peter Shower
    Hi Guys, i'm developing a 32bit Client-Application with Delphi. From this application I need to connect to databases on two different servers. First databse character set ist WE8MSWIN1252, the other server decodes with WE8PC850. Setting the client NLS_LANG parameter to the correct value solves correct sql-query results. Unfortunately this (the client character-set) seems only to be recognized on applications startup (first connect to oracle). I need to change the client-characterset at runtime. Oracle client seems to store the character set an application used to connect! beside: I#m using udl-files to setup the connections (Microsoft OLE DB - driver) what can I do?

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  • String Field Sizes for unicode database fields using different data access components

    - by Serg
    mjustin in his question 1 and question 2 says that TWideStringField.Size property for UTF8 fields in Delphi 2009 dbExpress is 4 times larger than the logical field size (max number of characters in the field). I inclined to consider this a dbExpress bug. That is what Delphi 2009 Help says: The interpretation of Size depends on the data type. The meaning of Size for data types that use it is given in the following table. For all other data types, Size is not used and its value is always 0. ftString - Size is the maximum number of characters in the string. I am using FibPlus 6.9.9 and it follows the above documentation - the string field size is the maximum number of characters, not bytes. So the question also implies the following question: Are DbExpress drivers in Delphi 2009 unusable for unicode databases?

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  • Visio 2010 Reverse Engineer Oracle

    - by digitall
    I have used Visio 2007 in the past to reverse engineer Oracle databases to get a flow scheme. I believe all Office 2007 products were x86 as well which is where I suspect my issue currently lies. I have since upgraded to Visio 2010 x64 and when I go to reverse engineer something from Oracle it shows up under Installed Visio Drivers but I can't seem to create a data source using it. My assumption here is it is because Oracle doesn't play nicely with x64 and with Visio being compiled as x64 I don't even get the option to use it. Has anyone done this with Visio 2010 x64 and Oracle yet? Or are there other tools you would recommend to reverse engineer and get a model such as the one generated by Visio?

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  • Mysql out of disk space

    - by Paddy
    I have just finished developing a rails app which has a mysql db as a backend. The app is meant for high traffic and will store lots of information. I am planning to set up my own web server and host the site from it. If in future my disk space runs out i would want to expand by adding more space. But say if my mysql database is housed in my /disk0s1 and by adding a new drive i have more partitions (and hence more disk space), how then would i extend my database to store information on those partitions too, and at the same time prevent any information from being written on the original partition. Should i go for multiple databases? if so how? If i went for a hosting solution i wouldn't be bothering about this as i would just have to worry about making payments for the extra space :) I always wondered how space is added on-the-go by these webhosts. Is there any specific mysql configuration that i have to make?

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  • Subsonic SQLite Multiple Files

    - by Marcus Vinicius de LIma
    Hi, I have an application that must be accessed for many users. To optimize the performance I intend to store each user profile information at a independant database file. I need everytime a user login the application, to setup a new provider linked with his own database. All databases have the same structure. So while querying user the commom generated DAL classes must switch for the database file relative the the user. Is there a way for configure SubSonic for doing that switch at runtime? Thanks.

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  • When to use CouchDB vs RDBMS

    - by Andrew Whitehouse
    I am looking at CouchDB, which has a number of appealing features over relational databases including: intuitive REST/HTTP interface easy replication data stored as documents, rather than normalised tables I appreciate that this is not a mature product so should be adopted with caution, but am wondering whether it is actually a viable replacement for an RDBMS (in spite of the intro page saying otherwise - http://couchdb.apache.org/docs/intro.html). Under what circumstances would CouchDB be a better choice of database than an RDBMS (e.g. MySQL), e.g. in terms of scalability, design + development time, reliability and maintenance. Are there still cases where an RDBMS is still clearly the right choice? Is this an either-or choice, or is a hybrid solution more likely to emerge as best practice?

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  • What are the requirements for an application health monitoring system?

    - by Steven A. Lowe
    What, at a minimum, should an application health-monitoring system do for you (the developer) and/or your boss (the IT Manager) and/or the oeprations (on-call) staff? What else should it do above the minimum requirements? Is monitoring the 'infrastructure' applications (ms-exchange, apache, etc.) sufficient or do individual user applications, web sites, and databases also need to be monitored? if the latter, what do you need to know about them? ADDENDUM: thanks for the input, i was really looking for application-level monitoring not infrastructure monitoring, but it is good to know about both

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  • Maximum number of workable tables in SQL Server And MySQL

    - by Kibbee
    I know that in SQL Server, the maximum number of "objects" in a database is a little over 2 billion. Objects contains tables, views, stored procedures, indexes, among other things . I'm not at all worried about going beyond 2 billion objects. However, what I would like to know, is, does SQL Server suffer a performance hit from having a large number of tables. Does each table you add have a performance hit, or is there basically no difference (assuming constant amount of data). Does anybody have any experience working with databases with thousands of tables? I'm also wondering the same about MySQL.

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  • Using MySQL as data source in Microsoft SQL Server Analysis Services

    - by coldilocks
    Hi, I have installed the latest .net connector (http://www.mysql.com/downloads/connector/net/), I can add MySQL databases as Data Sources, I can even browse through the data from Business Intelligence Studio. The problem is that I CANNOT create a datasource view, or if I do create one without tables, trying to add them after the fact gives me the same error. Specifically it looks like the data source view wizard tries to submit queries against the MySQL database using square brackets/braces, and the query bombs. I get an error message like: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '[my_db].[cheatType]' at line 2 So, in summary, has anyone been able to create a data source view using MySQL tables and, if so, can they please show me how this can be done. Thanks for any help!

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  • Sequence numbers best practice

    - by Abdullah Jibaly
    What's the best practice or well known methods to implement sequence numbers for business entities such as invoices, purchase orders, job numbers, etc? I want to be able to save the latest value in the database and be able to set it programatically. Is it OK to use a table for this purpose that has a SEQUENCE_NAME, SEQUENCE_NUMBER tuple? I know some databases have a first class sequence type but others (eg, MySQL) do not so it's not something I want to rely on. If a table is used to hold these sequences what is the right way to get and increment them in a synchronized fashion to ensure no data inconsistencies arise?

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  • Beginner SQL question: arithmetic with multiple COUNT(*) results

    - by polygenelubricants
    Continuing with the spirit of using the Stack Exchange Data Explorer to learn SQL, (see: Can we become our own “Northwind” for teaching SQL / databases?), I've decided to try to write a query to answer a simple question (on meta): What % of stackoverflow users have over 10,000 rep?. Here's what I've done: Query#1 SELECT COUNT(*) FROM Users WHERE Users.Reputation >= 10000 Result: 556 Query#2 SELECT COUNT(*) FROM USERS Result: 227691 Now, how do I put them together into one query? What is this query idiom called? What do I need to write so I can get, say, a one-row three-column result like this: 556 227691 0,00244190592

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  • Advice needed from PHP/Cake PHP expert

    - by Hiro
    I'm very new to programming (besides SQL and databases), but I ultimately want to master Cake PHP for web development. Now, given how new I am, I'm rather lost as to how I get started. Down the road, I want to use MVC framework so that I help myself be disciplined in the way I build. However, I know basic knowledge of PHP and OOP PHP are required. So my question is this: what are the right steps to mastering Cake PHP? I don't want to skip critical phases of learning before learning to Cake PHP. At the same time, I don't want to spend more time than required learning PHP if I can learn it directly through Cake PHP knowledge. Any advice would be appreciated.

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  • Guide for http://www.ch-werner.de/javasqlite java wrapper library for SQlite?

    - by Tom Nielsen
    I'm working on a large computer science school project using java and SQlite. After finding out that the zentus.org wrapper errors on databases with ON DELETE and ON UPDATE clauses set, I have changed to the other wrapper found at http://www.ch-werner.de/javasqlite. However, I find the documentation lacking somewhat when trying to get an overview on how it works and how to use it, and the function descriptions are very very short, and you have to scan through every function and somewhat guess how they work and what they do. I wasn't able to find any guides on google on how to use it. My question: Does anyone know a link for a guide or tutorial for the ch-werner.de/javasqlite wrapper, or else can give me a basic code example, or give a quick overview of querying the database and the most used functions, and how to use them?

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  • Filesystem synchronization library?

    - by IsaacB
    Hi, I've got 10 GB of files to back up daily to another site. The client is way out in the country so bandwidth is an issue. Does anyone know of any existing software or libraries out there that help with keeping a folder with its files synchronized across a slow link, that is it only sends files across if they have changed? Some kind of hash checking would be nice, too, to at least confirm the two sides are the same. I don't mind paying some money for it, seeing as how it might take me several weeks to a month to implement something decent on my own. I just don't want to re-invent the wheel, here. BTW it is a windows shop (they have an in house windows IT guy) so windows is preferred. I also have 10 GB of SQL Server 2000 databases to go across. Is the SQL server replication mode reliable? Thanks!

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  • Foreign keys in MySQL?

    - by icco
    I have been slowly learning SQL the last few weeks. I've picked up all of the relational algebra and the basics of how relational databases work. What I'm trying to do now is learn how it's implemented. A stumbling block I've come across in this, is foreign keys in MySQL. I can't seem to find much about the other than that they exist in the InnoDB storage schema that MySQL has. What is a simple example of foreign keys implemented in MySQL? Here's part of a schema I wrote that doesn't seem to be working if you would rather point out my flaw than show me a working example. CREATE TABLE `posts` ( `pID` bigint(20) NOT NULL auto_increment, `content` text NOT NULL, `time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP, `uID` bigint(20) NOT NULL, `wikiptr` bigint(20) default NULL, `cID` bigint(20) NOT NULL, PRIMARY KEY (`pID`), Foreign Key(`cID`) references categories, Foreign Key(`uID`) references users ) ENGINE=InnoDB;

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