rdbms

I have a number of different objects with a varying number of attributes. Until now I have saved the data in XML files which easily allow for an ever changing number of attributes. But I am trying to move it to a database. What would be your preferred way to store this data? A few strategies I have identified so far: Having one single field named "attributes" in the object's table and store the data serialized or json'ed in there. Storing the data in two tables (objects, attributes) and using a third to save the relations, making it a true n:m relation. Very clean solution, but possibly very

What kind of projects benefit from using a NoSQL database instead of rdbms wrapped by an ORM? Examples: Stackoverflow similiar sites? Social communities? forums? Niels van der Rest Your question is very general. NoSQL describes a collection of database techniques that are very different from each other. Roughly, there are: Key-value stores (Redis, Riak) Triplestores (AllegroGraph) Column-family stores (Bigtable, Cassandra) Document-oriented stores (CouchDB, MongoDB) Graph databases (Neo4j) A project can benefit from the use of a document database during the development phase of the project,

It is not entirely clear from MySQL documentation whether the InnoDB engine implements true serializable isolation 1 or snapshot isolation , which is often confusingly called "serializable" too. Which one is it? If MySQL InnoDB doesn't, are there any completely free, production-quality RDBMS which do? 1 where "true serializable isolation" means the absence of not only read anomalies as per the SQL standard, but also the write skew anomaly, explained in further detail here . regilero UPDATE: See comments, this seems to be fixed in MySQL 5.5 , with these examples we still have a table lock and

Most of the projects I've worked on have required many-to-many relationships in the database schema. For example, you might have the concept of Users and Groups, and the database might contain a table User, a table Group, and a table UserGroup to relate the two. I'm interested in the conceptual name of the UserGroup table in that example. I've grown accustomed to calling them "swing tables" because that's how I learned it, but I haven't heard other people use that term in a while. Instead, I've heard all of the following (including some new ones, thanks to all of you!): Association table

Modern RDBMS's have support for XML column types and functionality for dealing with XML in stored procedures. Historically I would always have mapped hierarchical data (whether of OO objects or XML) to relational tables. Given the widespread database support for XML should I change my ways? If you don't see the need then don't change! Sometimes you have to persist data that does not have a known structure, or its structure is very volatile. In those cases, instead of creating a table, just save the XML into your existing table I have a good real-life example. One of my clients receives an XML