deniskuzZ commented on PR #6159: URL: https://github.com/apache/hive/pull/6159#issuecomment-3527607546
> MVCC the transaction still holds the row lock in case of affected rows = 1, it might be rolled back in the middle of the transaction, so other updates need this transaction to commit or rollback to get the right version of this row(avoid to read dirty) ### Performance Comparison (Updates Only) | Aspect | MVCC + Retry | S4U NOWAIT + Retry | |--------|--------------|------------------| | **Locking** | Non-blocking (optimistic) | Immediate lock attempt, fails if locked | | **Retries** | Only if affected row changed | If row is locked | | **Throughput under low contention** | High | High | | **Throughput under high contention** | Medium (retries on conflicts) | Lower (more frequent failed locks) | | **CPU overhead** | Version checks + retry | Lock checks + retry loop | | **Latency** | Slightly variable due to retries | Immediate failure, retry adds latency | -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
