Understanding the UNABLE_TO_LOCK_ROW Error
The UNABLE_TO_LOCK_ROW error in Salesforce is a system-related record lock issue. This occurs when a transaction cannot obtain exclusive access to a record because another process is already updating it. Salesforce uses record locking to maintain data integrity in its multi-tenant environment.
Causes of the UNABLE_TO_LOCK_ROW Error
1. Concurrent Operations
Multiple processes attempting to modify the same record simultaneously. This commonly happens when batch jobs, triggers, flows, or multiple users try to update the same record at the same time.
2. Parent-Child Relationship Locks
When updating child records that have a master-detail relationship, Salesforce locks the parent record. If a parent record has thousands of child records, you're likely to encounter these errors as every child record edit locks the master record.
3. Time-out Issues
A transaction can only wait a maximum of 10 seconds for a lock to be released. If the parent record stays locked for more than 10 seconds when you try to obtain its lock to insert or update a child record, this error occurs.4. Sharing Recalculations
Sharing rules might lengthen the time of parent record locks. When records related to a parent account are updated, the parent is briefly locked to maintain database integrity and recalculate sharing.How to Handle the UNABLE_TO_LOCK_ROW Error
1. Implement Concurrency Controls
For integration apps and flows, configure a Concurrency ID lock template. Select your ID and configure the template, then save those settings and run the flow. This should resolve the UNABLE_TO_LOCK_ROW error.2. Optimize Queries with Proper Ordering
Look at your object relationships and make small enhancements in your query/code. Sometimes, simply ordering records together can resolve this issue. Consider using ORDER BY clauses in your SOQL queries to minimize lock contention.
3. Reduce Batch Sizes
Reducing your batch size can decrease the likelihood of locks, though this isn't a complete solution. For bulk operations, consider processing fewer records in each transaction.
4. Restructure Data Relationships
For parent-child relationship issues, consider dividing a single parent account into several and evenly distributing the child accounts between them. Group batches by limiting the scope to one parent account at a time.5. Use FOR UPDATE in SOQL Queries
In Apex, you can use FOR UPDATE to lock sObject records while they're being updated to prevent race conditions and thread safety problems. This ensures no other client or user can make updates to the record while you're processing it.
Conclusion
The UNABLE_TO_LOCK_ROW error is a common issue in Salesforce that occurs due to concurrent record access. By implementing proper concurrency controls, optimizing your queries, and restructuring your data relationships, you can significantly reduce these errors. Remember that this error is a result of Salesforce's attempt to maintain data integrity in its multi-tenant environment.