In his November 24 article Database Thaw Martin Fowler wrote about the lock-in of relational/SQL databases and some possible alternatives. I was with him until he wrote that “you can’t get [a] bigger breach of encapsulation than that,” referring to a central database shared by multiple applications. (The indented quotes below are verbatim from Fowler’s article).
For many organizations today, the primary pattern for integration is Shared Database Integration – where multiple applications are integrated by all using a common database. When you have these Integration Databases, it’s important that all these applications can easily get at this shared data – hence the all important role of SQL. The role of SQL as mostly-standard query language has been central to the dominance of databases.
That’s a fair argument, though I don’t agree that SQL has been central to the dominance of databases, or central to making shared database integration the “primary pattern” for integration. Before SQL-based databases took over in the mid-1980s, integration through shared non-relational databases was already the norm. SQL standardizes how users and application get data in and out of the database, and how database schemas are described, but it’s just a language that more or less replaced many proprietary and unstandardized languages that did the same thing.
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