Columnstore Deadlocking

Kendra Little shows us a scenario in which querying columnstore metadata during table updates can lead to a deadlock:

I was playing around with a nonclustered columnstore index on a disk-based table. Here’s what I was doing:

Session 1: this session repeatedly changed the value for a single row, back and forth. This puts it into the delta store.

Session 2: this session repeatedly counted the number of rows in the table, using the columnstore index.

With my sample data in this scenario, I found I frequently generated deadlocks.

Read on for more.

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