Introduction A relational database strong consistency model is based on ACID transaction properties. In this post we are going to unravel the reasons behind using different transaction isolation levels and various configuration patterns for both resource local and JTA transactions. Isolation and consistency In a relational database system, atomicity and durability are strict properties, while consistency and isolation are more or less configurable. We cannot even separate consistency from isolation as these two properties are always related. The lower the isolation level, the less consistent the system will get. From the least… Read More
Introduction A database is highly concurrent system. There’s always a chance of update conflicts, like when two concurring transactions try to update the same record. If there would be only one database transaction at any time then all operations would be executed sequentially. The challenge comes when multiple transactions try to update the same database rows as we still have to ensure consistent data state transitions. The SQL standard defines three consistency anomalies (phenomena): Dirty reads, prevented by Read Committed, Repeatable Read and Serializable isolation levels Non-repeatable reads, prevented by Repeatable Read… Read More
Introduction Transactions are omnipresent in today’s enterprise systems, providing data integrity even in highly concurrent environments. So let’s get started by first defining the term and the context where you might usually employ it. A transaction is a collection of read/write operations succeeding only if all contained operations succeed. Inherently a transaction is characterized by four properties (commonly referred as ACID): Atomicity Consistency Isolation Durability
I’ve been searching for the most suitable tools I’d use for my book writing process and I’ve settled for Asciidoctor. In the first place, I decided to use a markup text language that’s implicitly supported by GitHub, and after reviewing Markdown and Asciidoc, I opted for the latter for it offers a richer syntax.
We live in a world of both commercial and open-source software, each one having strengths and weaknesses. But when it comes to books, there hasn’t been any noticeable revolution towards embracing new writing methodologies. The current book market shares the same philosophy with commercial software business model. There is a fee for obtaining a book copy, evolution is rather slow and usually, there is a single person carrying all the weight of writing. It’s worth noticing that this model offers only the author’s point of view on a particular subject. Yet, there… Read More