I have three Clustered Columnstore Index (CCI) tables in SQL Server 2016. All of these CCIs are in the same partitioning scheme, based on Tenant ID. Lately, and inconsistently, I am getting deadlocks on simple select statements from joins to these tables. Example query that deadlocks:
SELECT TOP 33 r.tenantid FROM Table_r r INNER JOIN Table_cm cm ON r.MyKey=cm.MyKey INNER JOIN Table_pe pe ON r.MyKey=pe.MyKey WHERE r.TenantId = 69 AND pe.TenantId = 69 AND cm.TenantId = 69
Transaction (Process ID 56) was deadlocked on generic waitable object resources with another process and has been chosen as the deadlock victim. Rerun the transaction.
- If the query uses another index besides the CCI it does not deadlock.
- If I remove two of the three tenantid filters it does not deadlock.
- If I SELECT top 32 or lower it does not deadlock.
- If I add OPTION (MAXDOP 1) it does not deadlock.
- I can repro this in my scrambled PROD replica, PROD READ-ONLY Secondary, and PROD itself.
- I cannot repro this behavior in DEV or INT.
- It still deadlocks if I add WITH(NOLOCK) to all 3 table joins
- The query deadlocks itself. It will deadlock when there are no other active processes.
- Query plans without parallelism do not deadlock
Our PROD Version:
Microsoft SQL Server 2016 (SP2-CU5) (KB4475776) - 13.0.5264.1 (X64) Jan 10 2019 18:51:38 Copyright (c) Microsoft Corporation Enterprise Edition (64-bit) on Windows Server 2012 R2 Standard 6.3 (Build 9600: ) (Hypervisor)
How do I prevent deadlocks on this query?