Hibernate: Identifier
When using Hibernate: Must I identify an id or composite id for each entity, What about if I want to use table without any primary key and without composite key ... Thanx in advance ...
rdbms
Defuzzification process of fuzzy sets in RDBMS
I have a table that stores all values..eg x1, x2, x3 which determines fuzzy sets. Degree of membership is assigned to each using mathematical functions for Low, Med, High. My rule 1 states that if x1 is high AND x2 is medium then probability of output is z. I then take min{x1,x2} to evaluate the rule. Rule 2 states that if x2 is high...
How do the advanced features in Relational databases work?
To make a long question short, I know about the basics of a Relational Database, Indexing ,Replication, Locking, Concurrency, etc, and SQL syntax (SELECT,INSERT,UPDATE,DELETE, CREATE,DROP,ALTER,TRUNCATE) when used with simple expressions such as: SELECT EventID,EventName FROM Events WHERE CustomerID=5 ORDER BY EventType But I don't un...
ORMs are to RDBMSs as xxx is to OLAP cubes? Does xxx exist?
Is there an ORM-analogue for querying OLAP cubes / data-warehouses? I'm specifically interested in the .NET world, but generally interested in anything ;-) ...
Key-Value Stores vs. RDBMs vs. "Cloud" DBs (SDB)
I'm comfortable in the MySQL space having designed several apps over the past few years, and then continuously refining performance and scalability aspects. I also have some experience working with memcached to provide application side speed-ups on frequently queried result sets. And recently I implemented the Amazon SDB as my primary ...
Applications for using couchDB and a RDBMS together
Wondering if there was a scenario where one would use a document-based DB and a relational DB together in a best-of-both-worlds scenario? ...
Migrate from couchDB to RDBMS
Wondering if it is possible to migrate from a document-based DB (eg. couchDB) to a RDBMS (eg. MySQL). ...
Modeling Friends and Followers in an RDBMS
I'm trying to decide on the best way to model a relationship of records in a relational database. It's the classic friend/follow model: ~~~~ A User can have zero to many friends. A User can have zero to many followers. Friends and followers are both Users themselves. ~~~~~ What's the best way to model this? Thanks! ...
How should I approach migrating data from a "bad" database design to a usable design?
The current project I inherited mainly revolves around one unnormalized table. There are some attempts at normalization but the necessary constraints weren't put in place. Example: In the Project table, there is a client name (among other values) and there is also a clients table which just contains client names [no keys anywhere]. T...
What's the PostgreSQL equivalent of MSSQL's CONTEXT_INFO?
In relation to my other question "What’s the best way to audit log DELETEs?". What's the PostgreSQL equivalent of CONTEXT_INFO? [EDIT] I want to log deletes using trigger, but since i'm not using the database user as my app's logical user, I cannot log the CURRENT_USER from the trigger code as the user who deleted the record. But for...
Upgrading Informix - Switch to Oracle, Sybase or stay with Informix?
Hi, Previously I posted a question so I could confirm our current (albeit archaic) version of Informix here: http://stackoverflow.com/questions/682154/how-do-you-identify-informix-version-on-solaris (Thank you Jonathan and RET for clearing that up) We are definitely planning on upgrading but are first discussing if it would make more...
How do I migrate easily from MySQL to PostgreSQL?
I'd like to migrate an existing MySQL database (around 40tables, 400mb data) to Postgres before it gets bigger. I searched the web and tried some migration-scripts (some of them can be found here). None of them works seamlessly - if it would be just a few glitches I had to fix manually, it wouldn't be a problem, but the resulting dumps d...
Is a good idea to build in-memory indexes and circumvent the DB when operating intensively on a small subset?
I'm working on a program to automatically find optimal shift assignments, subject to lots of constraints. I'm using grails, i.e. the data about workers, shifts and assignments will be kept in a DBMS. For the optimization itself, I'll have to work very intensively on a small subset of the data (about 600 rows total from about 5 differen...
SQL Server 2005 - Trigger Loop?
I am using triggers for the first time. If I update a field in a table by an update trigger on the same table, with this spark a loop? Does sql server guard against this recursive behavior? Thanks ...
Recommendation for a small DBMS for use as a local datastore for a small .net app
I am looking for a local, relational datastore for a .net application. The datastore should ideally behave as a basic database with SQL for data retrieval and definition and transaction capability. It should not need a server and be easy to redistribute (i.e. only need a dll in the app to access a single db file). No support for access o...
Oracle DataGuard
Oracle DataGuard is a technique to replicate data stored in an Oracle RDBMS across several Oracle engine instances. I'm wondering whether DataGuard really provides a linear scalability for a RDBMS. Do you have any experiences with the DataGuard? How does it behave under heavy load conditions? ...
DB Tables which are in 3NF or 4NF but not in DKNF
Are there examples of Relational tables which are in 3NF or 4NF but not in Domain Key Normal Form? ...
Does Linq and projects like i4o make object oriented DBs a viable alternateive to relational DBs?
Given Linq and technologies like i4o is there any real reason why an object oriented database management system won't be a viable alternative to a relational database management system for new projects starting in the next 3 to 5 years? ...
Migrating from 'native' OODBMS to ORM (Entity Framework / SQL Server)
A while ago we started developing a new project which internally has about 25-30 different classes/types/models that are heavily related to each other either via 1:n, n:m or n:1 relationships. Back then we went with a native .net oodbms system basically because what it allowed us to do was to take our object model and simply add a few p...
RDBMS Key Confusion
I'm trying to sort out the database behind my company's website. We deal with both Sites and Residents. At the moment the Site Reference is included in the Residents table as a foreign key but, obviously, this is only in 1NF. Site references are of the form nnnnn (12345, for example). Each resident has their own reference within the Si...