PESSIMISTIC_READ and PESSIMISTIC_WRITE

Readers–writer lock A database system is a highly concurrent environment, therefore many concurrency theory idioms apply to database access as well. Concurrent changes must be serialized to preserve data integrity, so most database systems use a two-phase locking strategy, even if it’s usually supplemented by a Multiversion concurrency control mechanism. Because a mutual exclusion locking…

Spring transaction isolation level

Introduction Transaction isolation level is a concept that is not exclusive to the Spring framework. It is applied to transactions in general and is directly related with the ACID transaction properties. Isolation level defines how the changes made to some data repository by one transaction affect other simultaneous concurrent transactions, and also how and when…

angularjs filter

I think it’s best to understand what we even want to learn. To do that, we need to understand what filters really are and how we use them. For me, there are four types of filters. Yes, four, but there of course can be other variants. Let’s rattle through them: Filter 1: Static (single) use…