Isolation Level Basics

Randolph West describes the primary isolation levels in SQL Server:

There are four isolation levels in SQL Server (as quoted from SQL Server Books Online):

  • Read uncommitted (the lowest level where transactions are isolated only enough to ensure that physically corrupt data is not read)
  • Read committed (Database Engine default level)
  • Repeatable read
  • Serializable (the highest level, where transactions are completely isolated from one another)

Read on for a discussion of what these mean, as well as how optimistic versus pessimistic concurrency (in this case, Read Committed Snapshot Isolation versus Read Committed) comes into play.

Related Posts

Choosing Clustered Index Columns

Ed Elliott wades into the clustered index debate: I have seen this debated in forums spread over the internet for decades, and the advice that we gave ten years ago isn’t as valid today as it was then. Ten years ago, memory was considerably less, and disks were spinning rust. The advent of SSD’s and […]

Read More

Event-Driven Microservices

Saeed Barghi gives us an overview of what event-driven microservices are: Modern Microservices are all about making systems event-driven: instead of making remote requests and waiting for the response (services and components calling each other and tell each other what to do), we can send notifications to related microservices when an event occurs. These events […]

Read More

1 Comment

  • Randolph West on 2017-08-03

    I regret not using that terminology in the post, namely optimistic vs pessimistic. Thanks for mentioning it.

Comments are closed

Categories

August 2017
MTWTFSS
« Jul Sep »
 123456
78910111213
14151617181920
21222324252627
28293031