LCK_M_BU

Description

This wait occurs when a request is waiting to acquire a bulk update lock. These locks are required to protect objects during bulk import operations (e.g. WITH TABLOCK on bcp, SSIS or BULK INSERT commands). This wait typically occurs while requests are blocked by bulk import operations

Resolved by

DBAs and Developers

Suggested solutions

  1. Keep transaction durations short
  2. Ensure that transaction isolation levels are appropriate (avoid SERIALIZEABLE and REPEATABLE READ if possible)
  3. Investigate enabling the READ_COMMITTED_SNAPSHOT database setting
  4. Run trace/Profiler/Extended Event session in conjunction with Blocked Process Threshold to determine which queries are being blocked
  5. Indexing, ensure that long running queries and transactions are optimized
  6. Ensure that row, page and table locks are being escalated correctly. If the table is partitioned consider enabling partition escalation

Additional research

Lock Modes
Reducing SQL Server Locks
Understanding Isolation Levels
Identify the Cause of SQL Server Blocking
Lock Escalations

See more

Consider using ApexSQL Monitor, a Windows and SQL Server monitoring tool able to track SQL Server wait types, including the individual query wait statistics

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