SalesSQLDb1 experiences performance issues that are likely due to out-of-date statistics and frequent blocking queries.
A: Use sys.dm_pdw_nodes_tran_locks instead of sys.dm_tran_locks from Azure Synapse Analytics (SQL Data Warehouse) or Parallel Data Warehouse.
E: Example:
The following query will show blocking information.
SELECT
t1.resource_type,
t1.resource_database_id,
t1.resource_associated_entity_id,
t1.request_mode,
t1.request_session_id,
t2.blocking_session_id
FROM sys.dm_tran_locks as t1
INNER JOIN sys.dm_os_waiting_tasks as t2
ON t1.lock_owner_address = t2.resource_address;
Note: Depending on the system you're working with you can access these wait statistics from one of three locations:
sys.dm_os_wait_stats: for SQL Server
sys.dm_db_wait_stats: for Azure SQL Database
sys.dm_pdw_nodes_os_wait_stats: for Azure SQL Data Warehouse
Incorrect Answers:
F: sys.dm_tran_locks returns information about currently active lock manager resources in SQL Server 2019 (15.x). Each row represents a currently active request to the lock manager for a lock that has been granted or is waiting to be granted.
Instead use sys.dm_pdw_nodes_tran_locks.
Reference:
https://docs.microsoft.com/en-us/sql/relational-databases/system-dynamic-management-views/sys-dm-tran-locks-transact-sql