Can a transaction exits without a log file

A transaction cannot exist without a transaction log in SQL Server because the transaction log is the fundamental mechanism that enables transaction processing. Every transaction begins by generating log records, which are used to support rollback, crash recovery, durability, and consistency. SQL Server follows the Write-Ahead Logging protocol, meaning log records are generated and persisted before corresponding data page changes are considered durable. Without a transaction log, SQL Server would have no way to undo incomplete transactions, redo committed transactions after a crash, or maintain ACID guarantees. Even operations that are minimally logged still generate transaction log records. Therefore, while the amount of logging can vary, the existence of logging is mandatory. Every SQL Server database requires at least one transaction log file, and no transaction can execute without generating log records. This is why the transaction log is often described as the source of truth for SQL Server recovery and transaction management.

Every transaction—whether it's an INSERT, UPDATE, DELETE, SELECT (under certain isolation levels), or even a TRUNCATE TABLE—generates log records. SQL Server's Transaction Manager relies on the transaction log to support rollback, crash recovery, durability, and consistency. If there is no transaction log, SQL Server cannot guarantee ACID properties, so SQL Server does not allow a database to operate without at least one active log file.