Join Joey D'Antoni for an in-depth discussion in this video Transaction isolation, part of SQL Server Performance for Developers.
- [Instructor] Our next topic is isolation levels,…and this is a very under-looked…part of database performance.…The isolation level for your transaction…can affect a number of performance components.…How locks are taken, how locks are escalated…when data is being read, how long those relocks can be held,…and whether or not rows updated by another transaction…can be read before they're committed.…Low isolation levels do allow for more users…to be able to access the data so you can get…greater concurrency, but they can also affect data integrity…by creating the effect of lost updates and dirty reads.…
Dirty reads are a phenomenon where you…read uncommitted data.…That data could be wrong, because its transaction…hasn't been completed yet.…Higher isolation levels, like SERIALIZABLE,…can greatly increase blocking, and this can be…fairly unpredictable, because blocking is…dependent on how many users you have…concurrently accessing the system.…So if you're application testing does not spawn…multiple users, you may not notice this blocking problem.…
- Query execution
- How to read an execution plan
- What not to do with SQL Server
- Why cursors are bad
- Why scalar UDFs are expensive
- Datatypes and design
- What is a columnstore index?
- Transaction isolation
Skill Level Intermediate
1. Query Execution
2. What Not to Do with SQL Server
3. Datatypes and Design
4. Temporary Objects
7. Isolation Levels
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