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• mysql backup and restore from ib_logfile failure

  - by i need help

  Here's the case: After computer being hacked, we are in a rush to backup all data out to other computer. As a result, the mysql databases are not backup out as sql statement. What we have done is backup out all the physical files/folders in the C drive to new computer. Eg: C:\Program Files\MySQL\MySQL Server 4.1\data In this case, all data for mysql are inside unreadable file. Inside data folder consist of files like ib_logfile0, ib_logfile1, but not ib_data1 All database's table structure format are inside each respective folder. (Some folder have .frm, .opt) (some other folder have .frm, .myd, .myi) How can I retrieve back the data from the database in a new computer? I tried to install the same mysql version(4.1) at new computer, then replace all backup files inside data folder into this mysql in new computer. Then restart mysql service. When I restart, it fail: Could not start mysql service on local computer. error 1067: process terminated unexpectedly. Error log showing: InnoDB: The first specified data file .\ibdata1 did not exist: InnoDB: a new database to be created! 090930 10:24:49 InnoDB: Setting file .\ibdata1 size to 10 MB InnoDB: Database physically writes the file full: wait... InnoDB: Error: log file .\ib_logfile0 is of different size 0 87031808 bytes InnoDB: than specified in the .cnf file 0 25165824 bytes! 090930 10:24:49 [ERROR] Can't init databases 090930 10:24:49 [ERROR] Aborting 090930 10:24:49 [Note] C:\Program Files\MySQL\MySQL Server 4.1\bin\mysqld-nt: Shutdown complete

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• Schema objects not visible in SQL Server Management Studio 2008

  - by Germ

  I'm experiencing a weird problem with a SQL login. When I connect to the server in Microsoft SQL Server Management Studio (2008) using this account, I cannot see any of the tables, stored procedures etc. that this account should have access to on a particular database. When I connect to the same server within Visual Studio (2008) with the same account everything is there. When I connect with the same account on a Virtual Machine everything is there. I've also had a co-worker connect to the server using the same login and he's able to view everything as well. I use Microsoft SQL Server Management Studio all day connecting to different servers and databases and I've never experienced this problem. Does anyone have any suggestions on how I can diagnose this problem? I've checked to make sure I don't have any Table filters etc. There's several database on this server and I'm able to see the correct tables that this account has access to in the other databases just fine. Running this query lists the tables I'm expecting to see. SELECT * FROM INFORMATION_SCHEMA.TABLES

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• Question regarding the iPhone In App Purchase capabilities

  - by Wesley

  Hi everyone. I am working on releasing an app that will greatly benefit from using the in app purchase model. The app is a sort of book viewer, and the content I would like to make available for purchase will be more books in various languages. Each book is stored in sqlite format, in separate .db files. Now, the way that my developer has set it all up is that he added a line onto the bottom of the info.plist file called databases. Inside that database section, I can type in 'es' as the key, and for the value the name of the spanish database, and it populates in a uitableview in spanish, using NSLocale. So it is very easy to setup and implement different databases, which is great, but now I am confused about how I can implement my in app purchase model. Sorry about the long winded intro, here is my question: Is it possible to have an in app purchase add a line to my info.plist file? Or if not, is it possible to have the purchase reveal a new and updated plist file altogether that I would have already setup correctly? Any help here would be appreciated. Thanks

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• Cannot add SourceSafe Database as Visual Studio 2010 source control.

  - by CletusLoomis

  My issue is that I cannot add SourceSafe Database for source control within Visual Studio 2010. Our team was initially using VSS for source control in Visual Studio 2010. During an evaluation of TFS, I switched my source control to TFS. It will be a few weeks before a decision is made on TFS, so I needed to switch my source control back to VSS. However I'm now unable to add a SourceSafe Database in Visual Studio. Steps to Reproduce in Visual Studio 2010: 1) Access the 'Open SourceSafe Database' form via Tools-Options-Source Control-Plug-in Settings--Advanced or via File-Source Control 2) The list of available database is blank so I choose 'Browse'. 3) I browse to the srcsafe.ini file for my VSS database and select it. 4) I'm promted to confirm the Database Name - Click OK. 5) The database does not appear in the 'Open SourceSafe' Database form. The list of available databases is still blank. Note that I can add the database fine outside of Visual Studio using VSS directly. However the databases I add via VSS do not appear in the Visual Studio forms. I'm suspicious that this is related to "down-grading" from TFS to VSS which may not have been heavily tested at MS. Any assistance is appreciated.

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• How to best handle exception to repeating calendar events

  - by blcArmadillo

  I'm working on a project that will require me to implement a calendar. I'm trying to come up with a system that is very flexible: can handle repeating events, exceptions to repeats, etc. I've looked at the schema for applications like iCal, Lotus Notes, and Mozilla to get an idea of how to go about implementing such a system. Currently I'm having trouble deciding what is the best way to handle exceptions to repeating events. I've used databases quite a bit but don't have a ton of experience with really optimizing everything so I'm not sure which method of the two I'm considering would be optimal in terms of overall performance and ability to query/search: Breaking the repeating event. So taking the changing the ending date on the current row for the repeating event, inserting a new row with the exception, and adding another row continuing the old sequence. Simply adding an exception. So adding a new row with some field that indicates it as an override. So here is why I can't decide. Method one will result in a lot more rows since each edit requires 2 extra rows as apposed to only one row by the second method. On the other hand I think the query to find an event would be much simper, and thus possibly faster(?) using the first method. The second method seems like it will require more calculating on the application server since once you get the data you'll have to remove the intersection of the two rows. I know databases are often the bottleneck for websites and while I'm sure a lot of you are thinking either is fine because your project will probably never get large enough for the difference in efficiency to really matter, I'd still like to implement the best solution. So what method would you guys pick, or would you do something completely different? Also, as a side note I'll be using MySQL and PHP. If there is another technology that you think would be better suited for this, especially in the database area, please mention it. Thanks for the advice.

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• OData / WCF Data Service - HTTP 500 Error

  - by Eric

  I have created an OData/WCF service using Visual Studio 2010 on Windows XP SP3 with all current patches installed. When I click on "view in browser", the service opens and I see the 3 tables from my EF model. However, when I add a table name ("Commands" in this case) to the end of the query string, rather than seeing the data from the table, I get an HTTP 500 error. (This error (HTTP 500 Internal Server Error) means that the website you are visiting had a server problem which prevented the webpage from displaying.). I have not only followed the examples from 2 sites, but have also tried running the sample application that the blog poster sent me (that works on his machine), and still am not having any luck. The blog post is at Exposing OData from an Entity Framework Model Does anyone have an idea why this is occurring and how to resolve it? Here is the output of the "View in Browser": <?xml version="1.0" encoding="utf-8" standalone="yes" ?> - <service xml:base="http://localhost:1883/VistaDBCommandService.svc/" xmlns:atom="http://www.w3.org/2005/Atom" xmlns:app="http://www.w3.org/2007/app" xmlns="http://www.w3.org/2007/app"> - <workspace> <atom:title>Default</atom:title> - <collection href="Commands"> <atom:title>Commands</atom:title> </collection> - <collection href="Databases"> <atom:title>Databases</atom:title> </collection> - <collection href="Statuses"> <atom:title>Statuses</atom:title> </collection> </workspace> </service> ============================= Thanks, Eric

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• What strategy do you use to sync your code when working from home

  - by Ben Daniel

  At my work I currently have my development environment inside a Virtual Machine. When I need to do work from home I copy my VM and any databases I need onto a laptop drive sized external USB drive. After about 10 minutes of copying I put the drive in my pocket and head home, copy back the VM and databases onto my personal computer and I'm ready to work. I follow the same steps to take the work back with me. So if I count the total amount of time I spend waiting around for files to finish copying in order for me to take work home and bring it back again, it comes to around 40 minutes! I do have a VPN connection to my work from home (providing the internet is up at both sites) and a decent internet speed (8mbits down/?up) but I find Remote Desktoping into my work machine laggy enough for me to want to work on my VM directly. So in looking at what other options I have or how I could improve my existing option I'm interested in what strategy you use or recommend to do work at home and keeping your code/environment in sync. EDIT: I'd prefer an option where I don't have to commit my changes into version control before I leave work - as I like to make meaningful descriptive comments in my commits, committing would take longer than just copying my VM onto a portable drive! lol Also I'd prefer a solution where my dev environment stays in sync too. Having said that I'm still very interested in your own solutions even if they don't exactly solve my problem as best as I'd like. :)

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• Variant datatype library for C

  - by Joey Adams

  Is there a decent open-source C library for storing and manipulating dynamically-typed variables (a.k.a. variants)? I'm primarily interested in atomic values (int8, int16, int32, uint, strings, blobs, etc.), while JSON-style arrays and objects as well as custom objects would also be nice. A major case where such a library would be useful is in working with SQL databases. The most obvious feature of such a library would be a single type for all supported values, e.g.: struct Variant { enum Type type; union { int8_t int8_; int16_t int16_; // ... }; }; Other features might include converting Variant objects to/from C structures (using a binding table), converting values to/from strings, and integration with an existing database library such as SQLite. Note: I do not believe this is question is a duplicate of http://stackoverflow.com/questions/649649/any-library-for-generic-datatypes-in-c , which refers to "queues, trees, maps, lists". What I'm talking about focuses more on making working with SQL databases roughly as smooth as working with them in interpreted languages.

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• open source business intelligence solutions

  - by opensas

  which open source business intelligence solution would you recommend? All I need is to build some cubes and let the end user play with dimensions, filter data, sort, etc, and once it's done being able to export it to excel... I'd like the solution to be as simple and easy on resources as possible, and also I'd like it to be as much open source as possible, by the way. I've heard that many solutions available do have many restrictions when it comes to there community version. I'd like to ear your advices and the pros/cons of each alternative, to help me choose the right tool, and if you could point me to some basic demo and tutorial to get started. thanks a lot ps: I'm using sql server databases, they aren't huge databases (in general less than a million records) and I doesn't necessarily have to work on "live" data... ps: some useful links: http://en.wikipedia.org/wiki/Business_intelligence_tools#Open_source_free_products http://www.manageability.org/blog/stuff/open-source-java-business-intelligence http://www.jaspersoft.com/jasperanalysis http://community.pentaho.com/projects/bi_platform/ http://community.pentaho.com/faq/platform_licensing.php http://www.eclipse.org/birt/phoenix/ http://www.spagoworld.org/xwiki/bin/view/SpagoWorld/ http://docs.google.com/viewer?a=v&q=cache:vhsqMQXwCUkJ:www.ow2.org/xwiki/bin/download/Activities/EuropeLocalChapterWebinars/ELCWebinarOSBI.pdf+open+source+business+intelligence&hl=en&pid=bl&srcid=ADGEESgpJJ2MqaKprJQOF2jX2UXCZQjg_asv8d7EVYtq0Vma-e-tR1tFxS-I0SOW0IhJC5acYc94rkDOrgP1WckCp_vk4qhKqR9y2Klp_u9cL8hlXoKoUpMkpAd5wabu61A4W0y15E5P&sig=AHIEtbRJ5FAI-3YK-qtayPjKkF_CwOgZag

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• JPA - Performance with using multiple entity manager

  - by Nguyen Tuan Linh

  My situation is: The code is not mine I have two kinds of database: one is Dad, one is Son. In Dad, I have a table to store JNDI name. I will look up Dad using JNDI, create entity manager, and retrieve this table. From these retrieved JNDI names, I will create multiple entity managers using multiple Son databases. The problem is: Son have thousands of entities. It takes each Son database around 10 minutes to load all entities. If there is 4 Son databases, it will be 40 minutes. My question: Is there any way to load all entities and use them for all entity manager? Please look at the code below For each Son JNDI: Map<String, String> puSonProperties = new HashMap<String, String>(); puSonProperties.put("javax.persistence.jtaDataSource", sonJndi); EntityManagerFactory emf = Persistence.createEntityManagerFactory("PUSon", puSonProperties); PUSon - All of them use the same persistence unit log.info("Verify entity manager for son: {0} - {1}", sonCode, emSon.find(Son_configuration.class, 0) != null ? "ok" : "failed!"); This is the actual code where the loading of all entities begins. 10 mins.

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• Is it possible to update old database from dbml file ? (C#, .Net 4, Linq, SQL Server)

  - by Emil

  Hi all, I began recently a new job, a very interesting project (C#,.Net 4, Linq, VS 2010 and SQL Server). And immediately I got a very exciting challenge: I must implement either a new tool or integrate the logic when program start, or whatever, but what must happen is the following: the customers have previous application and database (full with their specific data). Now a new version is ready and the customer gets the update. In the mean time we made some modification on DB (new table, columns, maybe an old column deleted, or whatever). I’m pretty new in Linq and also SQL databases and my first solution can be: I check the applications/databases version and implement all the changes step by step comparing all tables, columns, keys, constrains, etc. (all this new information I have in my dbml and the old I asked from the existing DB). And I’ll do this each time the version changed. But somehow I feel, this is NOT a smart solution so I look for a general solution of this problem. Is there a way to update customers DB from the dbml file? To create a new one is not a problem (CreateDatabase with DataContext), is there any update/alter database methods? I guess I’m not the only one who search for such a solution (I found nothing in internet – or I looked for bad keywords). How did you solve this problem? I look also for an external tool, but first for a solution with C#, Linq or something similar. For any idea thank you in advance! Best regards, Emil

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• New to web development - backend questions

  - by James

  I'm new to web development although I'm confident in the roadmap for the front-end. I need direction on two things: Basic architecture Back-end technologies For architecture, what do I need to get started? From what I know, its: Get a domain name registered (godaddy?) Find a web host ??? anything else? or start developing the site? I don't think its that easy, there must be something I'm missing, right? For the back-end technologies, I have application development experience with Java and Python, but how likely is it to find a back-end hosting site that supports these languages over PHP? Is PHP a better choice? If I stick with what I know for the back-end, am I sabotaging myself later on? If I need help, how is the market for a python/java developer vs. a php developer? What do I need to know about databases? I have some basic SQL experience. Do hosting sites have limitations on the type of databases or bandwidth I need to worry about? I'm working through some of the common sites: StackOverflow, Sitepoint forums, Google, etc...are there other resources I should use?

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• While trying to set up Django on Windows: AttributeError: 'Settings' object has no attribute 'DATABA

  - by user326370

  I'm following these instructions in order to set up Django on Windows. I have installed Python 2.6, PostgreSQL 8.4, Psycopg 2.0.14 for Python 2.6 and the latest version of Django from SVN. I'm now following these instructions to run a test project (copied from the page linked to above): C:\Documents and Settings\John>cd C:\ C:\>mkdir django C:\>cd django C:\django>django-admin.py startproject testproject C:\django>cd testproject C:\django\testproject>python manage.py runserver When I run the last line, this is the output: Validating models... Unhandled exception in thread started by <function inner_run at 0x01ECB930> Traceback (most recent call last): File "J:\Python26\lib\site-packages\django\core\management\commands\runserver.py", line 48, in inn er_run self.validate(display_num_errors=True) File "J:\Python26\lib\site-packages\django\core\management\base.py", line 249, in validate num_errors = get_validation_errors(s, app) File "J:\Python26\lib\site-packages\django\core\management\validation.py", line 22, in get_validat ion_errors from django.db import models, connection File "J:\Python26\lib\site-packages\django\db\__init__.py", line 14, in <module> if not settings.DATABASES: File "J:\Python26\lib\site-packages\django\utils\functional.py", line 273, in __getattr__ return getattr(self._wrapped, name) AttributeError: 'Settings' object has no attribute 'DATABASES' Did I forget to do something with the database? Any help will be appreciated. Thank you!

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• Are Parameters really enough to prevent Sql injections?

  - by Rune Grimstad

  I've been preaching both to my colleagues and here on SO about the goodness of using parameters in SQL queries, especially in .NET applications. I've even gone so far as to promise them as giving immunity against SQL injection attacks. But I'm starting to wonder if this really is true. Are there any known SQL injection attacks that will be successfull against a parameterized query? Can you for example send a string that causes a buffer overflow on the server? There are of course other considerations to make to ensure that a web application is safe (like sanitizing user input and all that stuff) but now I am thinking of SQL injections. I'm especially interested in attacks against MsSQL 2005 and 2008 since they are my primary databases, but all databases are interesting. Edit: To clarify what I mean by parameters and parameterized queries. By using parameters I mean using "variables" instead of building the sql query in a string. So instead of doing this: SELECT * FROM Table WHERE Name = 'a name' We do this: SELECT * FROM Table WHERE Name = @Name and then set the value of the @Name parameter on the query / command object.

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• Test-First development tool for SQL Server 2005?

  - by Jeff Jones

  For several years I have been using a testing tool called qmTest that allows me to do test-driven database development for some Firebird databases. I write a test for a new feature (table, trigger, stored procedure, etc.) until it fails, then modify the database until the test passes. If necessary, I do more work on the test until it fails again, then modify the database until the test passes. Once the test for the feature is complete and passes 100% of the time, I save it in a suite of other tests for the database. Before moving on to another test or a deployment, I run all the tests as a suite to make sure nothing is broken. Tests can have dependencies on other tests, and the results are recorded and displayed in a browser. Nothing new here, I am sure. Our shop is aiming toward standardizing on MSSQLServer and I want to use the same procedure for developing our databases. Does anyone know of tools that allow or encourage this kind of development? I believe the Team System does, but we do not own that at this point, and probably will not for some time. I am not opposed to scripting, but would welcome a more graphical environment. Any suggestions?

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• Is it possible to unstick a remote IIS ASP server after an exception hangs the session?

  - by user89691

  I have been coding an app in classic ASP that accesses 2 Access databases. I had a page I was working on throw an exception, which is normal during development and causes no lasting problems. This time however, after the exception any attempt to open either of the databases would freeze the session with an infinite script timeout. If I delete the session cookie I an able to access ASP pages again until I try to open the database again. The database that was open when the exception was thrown is left open. There is a LDB lock file and I can't rename or delete either the LDB or MDB file, though I can download the MDB file with FTP. The 2nd access database is not open but any attempt to read this also hangs the session. Accessing HTML pages is fine. The site is hosted with Hostway and they are not interested ("Coding problem = Your problem" even though it leaves my site dead in the water, I suspect until the next reboot, whenever that might be). Here is the dump from the relevant ASP page that threw the exception: Active Server Pages error 'ASP 0115' Unexpected error /translatestats.asp A trappable error (C0000005) occurred in an external object. The script cannot continue running. Active Server Pages error 'ASP 0240' Script Engine Exception /translatestats.asp A ScriptEngine threw exception 'C0000005' in 'IActiveScript::Close()' from 'CActiveScriptEngine::FinalRelease()'. Is there any way I can unstick the site / force close the database remotely ?

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• MongoDB - proper use of collections?

  - by zmg

  In Mongo my understanding is that you can have databases and collections. I'm working on a social-type app that will have blogs and comments (among other things) and had previously be using MySQL and pretty heavy partitioning in an attempt to limit possible concurrency issues. With MySQL I've stuffed all my user data into a _user database with several tables to further partition the data (blogs, pages, etc). My immediate reaction with Mongo would be to create a 'users' database with one collection per user. In this way user 'zach' blog entries would go into the 'zach' collection with associated comments and such becoming sub-objects in the same collection. Basically like dynamically creating one table per user in MySQL, but apparently without the complexity and limitations that might impose. Of course since I haven't really used Mongo before I'm having trouble gauging the (ahem..) quality of this idea and the potential problems it might cause down the road. I'd like user data to be treated a lot like a users directory in a *nix environment where user created/non-shared (mostly) gets put into one place (currently with MySQL that would be the appname_users as mentioned above). Most of the users data will be specific to the users page(s). Some of the user data which is queried across all site users (searchable user profiles) is currently kept in a separate database/table and I expect things like this could be put into a appname_system database and be broken up into collections and/or application specific databases (appname_profiles). Anyway, since the available documentation on this is currently a little thin and my experience is extremely limited I thought I might find a little guidance from someone with a better working understanding of the system. On the plus side I'd really already been attempting to treat MySQL as a schema-less document-store and doing this with Mongo seems much more intuitive/sane/rational so I'm really looking forward to getting started. Thanks, Zach

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• Is there an XML XQuery interface to existing XML files?

  - by xsaero00

  My company is in education industry and we use XML to store course content. We also store some course related information (mostly metainfo) in relational database. Right now we are in the process of switching from our proprietary XML Schema to DocBook 5. Along with the switch we want to move course related information from database to XML files. The reason for this is to have all course data in one place and to put it under Subversion. However, we would like to keep flexibility of the relational database and be able to easily extract specific information about a course from an XML document. XQuery seems to be up to the task so I was researching databases that supports it but so far could not find what I needed. What I basically want, is to have my XML files in a certain directory structure and then on top of this I would like to have a system that would index my files and let me select anything out of any file using XQuery. This way I can have "my cake and eat it too": I will have XQuery interface and still keep my files in plain text and versioned. Is there anything out there at least remotely resembling to what I want? If you think that what I an asking for is nonsense please make an alternative suggestion. On the related note: What XML Databases (preferably native and open source) do you have experience with and what would you recommend?

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• MS SQL : Can you help me with this query?

  - by rlb.usa

  I want to run a diagnostic report on our MS SQL 2008 database server. I am looping through all of the databases, and then for each database, I want to look at each table. But, when I go to look at each table (with tbl_cursor), it always picks up the tables in the database 'master'. I think it's because of my tbl_cursor selection : SELECT table_name FROM information_schema.tables WHERE table_type = 'base table' How do I fix this? Here's the entire code: SET NOCOUNT ON DECLARE @table_count INT DECLARE @db_cursor VARCHAR(100) DECLARE database_cursor CURSOR FOR SELECT name FROM sys.databases where name<>N'master' OPEN database_cursor FETCH NEXT FROM database_cursor INTO @db_cursor WHILE @@Fetch_status = 0 BEGIN PRINT @db_cursor SET @table_count = 0 DECLARE @table_cursor VARCHAR(100) DECLARE tbl_cursor CURSOR FOR SELECT table_name FROM information_schema.tables WHERE table_type = 'base table' OPEN tbl_cursor FETCH NEXT FROM tbl_cursor INTO @table_cursor WHILE @@Fetch_status = 0 BEGIN DECLARE @table_cmd NVARCHAR(255) SET @table_cmd = N'IF NOT EXISTS( SELECT TOP(1) * FROM ' + @table_cursor + ') PRINT N'' Table ''''' + @table_cursor + ''''' is empty'' ' --PRINT @table_cmd --debug EXEC sp_executesql @table_cmd SET @table_count = @table_count + 1 FETCH NEXT FROM tbl_cursor INTO @table_cursor END CLOSE tbl_cursor DEALLOCATE tbl_cursor PRINT @db_cursor + N' Total Tables : ' + CAST( @table_count as varchar(2) ) PRINT N'' -- print another blank line SET @table_count = 0 FETCH NEXT FROM database_cursor INTO @db_cursor END CLOSE database_cursor DEALLOCATE database_cursor SET NOCOUNT OFF

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• SQL Server database change workflow best practices

  - by kubi

  The Background My group has 4 SQL Server Databases: Production UAT Test Dev I work in the Dev environment. When the time comes to promote the objects I've been working on (tables, views, functions, stored procs) I make a request of my manager, who promotes to Test. After testing, she submits a request to an Admin who promotes to UAT. After successful user testing, the same Admin promotes to Production. The Problem The entire process is awkward for a few reasons. Each person must manually track their changes. If I update, add, remove any objects I need to track them so that my promotion request contains everything I've done. In theory, if I miss something testing or UAT should catch it, but this isn't certain and it's a waste of the tester's time, anyway. Lots of changes I make are iterative and done in a GUI, which means there's no record of what changes I made, only the end result (at least as far as I know). We're in the fairly early stages of building out a data mart, so the majority of the changes made, at least count-wise, are minor things: changing the data type for a column, altering the names of tables as we crystallize what they'll be used for, tweaking functions and stored procs, etc. The Question People have been doing this kind of work for decades, so I imagine there have got to be a much better way to manage the process. What I would love is if I could run a diff between two databases to see how the structure was different, use that diff to generate a change script, use that change script as my promotion request. Is this possible? If not, are there any other ways to organize this process? For the record, we're a 100% Microsoft shop, just now updating everything to SQL Server 2008, so any tools available in that package would be fair game.

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• PHP Database connection practice

  - by Phill Pafford

  I have a script that connects to multiple databases (Oracle, MySQL and MSSQL), each database connection might not be used each time the script runs but all could be used in a single script execution. My question is, "Is it better to connect to all the databases once in the beginning of the script even though all the connections might not be used. Or is it better to connect to them as needed, the only catch is that I would need to have the connection call in a loop (so the database connection would be new for X amount of times in the loop). Yeah Example Code #1: // Connections at the beginning of the script $dbh_oracle = connect2db(); $dbh_mysql = connect2db(); $dbh_mssql = connect2db(); for ($i=1; $i<=5; $i++) { // NOTE: might not use all the connections $rs = queryDb($query,$dbh_*); // $dbh can be any of the 3 connections } Yeah Example Code #2: // Connections in the loop for ($i=1; $i<=5; $i++) { // NOTE: Would use all the connections but connecting multiple times $dbh_oracle = connect2db(); $dbh_mysql = connect2db(); $dbh_mssql = connect2db(); $rs_oracle = queryDb($query,$dbh_oracle); $rs_mysql = queryDb($query,$dbh_mysql); $rs_mssql = queryDb($query,$dbh_mssql); } now I know you could use a persistent connection but would that be one connection open for each database in the loop as well? Like mysql_pconnect(), mssql_pconnect() and adodb for Oracle persistent connection method. I know that persistent connection can also be resource hogs and as I'm looking for best performance/practice.

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• Auto increment with a Unit Of Work

  - by Derick

  Context I'm building a persistence layer to abstract different types of databases that I'll be needing. On the relational part I have mySQL, Oracle and PostgreSQL. Let's take the following simplified MySQL tables: CREATE TABLE Contact ( ID varchar(15), NAME varchar(30) ); CREATE TABLE Address ( ID varchar(15), CONTACT_ID varchar(15), NAME varchar(50) ); I use code to generate system specific alpha numeric unique ID's fitting 15 chars in this case. Thus, if I insert a Contact record with it's Addresses I have my generated Contact.ID and Address.CONTACT_IDs before committing. I've created a Unit of Work (amongst others) as per Martin Fowler's patterns to add transaction support. I'm using a key based Identity Map in the UoW to track the changed records in memory. It works like a charm for the scenario above, all pretty standard stuff so far. The question scenario comes in when I have a database that is not under my control and the ID fields are auto-increment (or in Oracle sequences). In this case I do not have the db generated Contact.ID beforehand, so when I create my Address I do not have a value for Address.CONTACT_ID. The transaction has not been started on the DB session since all is kept in the Identity Map in memory. Question: What is a good approach to address this? (Avoiding unnecessary db round trips) Some ideas: Retrieve the last ID: I can do a call to the database to retrieve the last Id like: SELECT Auto_increment FROM information_schema.tables WHERE table_name='Contact'; But this is MySQL specific and probably something similar can be done for the other databases. If do this then would need to do the 1st insert, get the ID and then update the children (Address.CONTACT_IDs) – all in the current transaction context.

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• Why isn't the Cache invalidated after table update using the SqlCacheDependency?

  - by Jason

  I have been trying to get SqlCacheDependency working. I think I have everything set up correctly, but when I update the table, the item in the Cache isn't invalidated. Can you look at my code and see if I am missing anything? I enabled the Service Broker for the Sandbox database. I have placed the following code in the Global.asax file. I also restart IIS to make sure it is called. void Application_Start(object sender, EventArgs e) { SqlDependency.Start(ConfigurationManager.ConnectionStrings["SandboxConnectionString"].ConnectionString); } I have placed this entry in the web.config file: <system.web> <caching> <sqlCacheDependency enabled="true" pollTime="10000"> <databases> <add name="Sandbox" connectionStringName="SandboxConnectionString"/> </databases> </sqlCacheDependency> </caching> </system.web> I call this code to put the item into the cache: protected void CacheDataSetButton_Click(object sender, EventArgs e) { using (SqlConnection sqlConnection = new SqlConnection(ConfigurationManager.ConnectionStrings["SandboxConnectionString"].ConnectionString)) { using (SqlCommand sqlCommand = new SqlCommand("SELECT PetID, Name, Breed, Age, Sex, Fixed, Microchipped FROM dbo.Pets", sqlConnection)) { using (SqlDataAdapter sqlDataAdapter = new SqlDataAdapter(sqlCommand)) { DataSet petsDataSet = new DataSet(); sqlDataAdapter.Fill(petsDataSet, "Pets"); SqlCacheDependency petsSqlCacheDependency = new SqlCacheDependency(sqlCommand); Cache.Insert("Pets", petsDataSet, petsSqlCacheDependency, DateTime.Now.AddSeconds(10), Cache.NoSlidingExpiration); } } } } Then I bind the GridView with this code: protected void BindGridViewButton_Click(object sender, EventArgs e) { if (Cache["Pets"] != null) { GridView1.DataSource = Cache["Pets"] as DataSet; GridView1.DataBind(); } } Between attempts to DataBind the GridView, I change the table's values expecting it to invalidate the Cache["Pets"] item, but it seems to stay in the Cache indefinitely.

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• Database structure for ecommerce site

  - by imanc

  Hey Guys, I have been tasked with designing an ecommerce solution. The aspect that is causing me the most problems is the database. Currently the site consists of 10+ country based shops each with their own database (all residing on the same mysql instance). For the new site I'd rather all these shop databases be merged into one database so that all tables (products, orders, customers etc.) have a shop_id field. From a programming perspective this seems to make the most sense as we won't have to manage data across multiple databases. Currently the entire site generates about 120k orders a year, but is experiencing fairly heavy growth and we need to design a solution that will scale. In 5 years there may be more than a million orders per year and a database that contains 5 years order history (archiving maybe a solution here). The question is - do we use a single database, or do we keep the database-per-shop structure? I am currently trying to find supporting evidence for either avenue. The company I am designing the solution for prefer the per-shop database structure because they believe it will allow the sites to scale. But my argument is that the shop's database probably won't get that busy over the next few years that they exceed the capacity of a mysql database and a "no expenses spared" hardware set-up. I am wondering if anyone has any advice either way? Does anyone have experience with websites / ecommerce sites that have tables containing millions of records? I know there is probably not a clear answer here, but at what stage do we have too many records or too large table files to have a fast loading site? Also, if anyone has any advice on sources of information - books, websites, etc. where I can do further research, it would be highly appreciated! Cheers, imanc

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• Performance of Multiple Joins

  - by geeko

  Greetings Overflowers, I need to query against objects with many/complex spacial conditions. In relational databases that is translated to many joins (possibly 10+). I'm new to this business and wondering whether to go with MS SQL Server 2008 R2 or Oracle 11g or document-based solutions such as RavenDB or simply go with some spacial database (GIS)... Any thoughts ? Regards UPDATE: Thank you all for your answers. Would anybody opt for document/spatial databases ? My database would consist of tens of millions to few billion records. Mostly read-only. Almost no updates unless in case of mistakes in input. Overnight inserts and not that frequent. The join tables are predicted beforehand but the number of self joins (tables joining themselves multiple times) is not. Small pages of results from such queries are going to be viewed on an highly interactive website so response time is critical. Any predictions on how this can perform on MS SQL Server 2008 R2 or Oracle 11g ? I'm also concerned about boosting performance by adding more servers, which one scales better ? How about PostgresQL ?

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