Locks, Blocks, and Snapshots: Maximizing Database Concurrency

Target Audience:

DBAs, developers, and anyone else curious about how isolation levels can affect the performance and accuracy of a query.


The ability for multiple processes to query and update a database concurrently has long-been a hallmark of database technology, but this feature can be implemented in many ways. This session will explore the different isolation levels supported by SQL Server and Azure SQL Database, why they exist, how they work, how they differ, and how In-Memory OLTP fits in. Demonstrations will also show how different isolation levels can determine not only the performance, but also the result set returned by a query. Additionally, attendees will learn how to choose the optimal isolation level for a given workload, and see how easy it can be to improve performance by adjusting isolation settings. An understanding of SQL Server’s isolation levels can help relieve bottlenecks that no amount of query tuning or indexing can address – attend this session and gain Senior DBA-level skills on how to maximize your database’s ability to process transactions concurrently.

Why I Want to Present This Session:

This topic came from my desire to find a way to easily describe these seemingly-complex issues which can affect any database workload.

Additional Resources:

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Bob Pusateri is a Microsoft Certified Master, DBA, and systems architect with over 10 years experience on SQL Server. His interests involve internals, performance optimization, and cloud technologies. He is an active member of both Chicago-area PASS Local Groups, a community speaker, and maintains a web presence through both Twitter (@SQLBob) and his blog (bobpusateri.com).
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1 Comment. Leave new

Eugene Meidinger
September 14, 2019 9:42 am

Overall a good abstract. I’ve break it into two paragraphs to improve readability. I’d also consider having a “why should I care?” answer in the first sentence or two. If someone has never heard about isolation levels before, it’s not clear until the very end how this functionality impacts them. I think you could easily give an example of negative consequences from getting this wrong.


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