Lag between Spring #Transaction finish and actual DB commit - spring

Question

I have a simple SpringBoot application, which is using SpringData and has the next structure
SlotConfigsController -> Repository (CrudRepository)
#RestController
#RequiredArgsConstructor
public class ConfigsController {
private final ConfigsRepository configsRepository;
#PostMapping(path = "/configs")
public ResponseEntity<Void> saveConfig(#RequestBody ConfigDto config) {
ConfigEntity config = CONFIGS_MAPPER.dtoToEntity(config);
configsRepository.save(config);
log.info("Transactional method finished");
}
}
Repository
#Repository
public interface ConfigsRepository extends CrudRepository<ConfigsEntity, Long> {
#Transactional
ConfigsEntity save(ConfigsEntity entity);
}
I started Postgres DB using docker-compose and enabled logs via
environment:
- EXTRA_CONF=log_statement=all
What I noticed during the log analysis is that the actual DB commit (inside the docker log) occurs after the log.info(...) call.
Here is the log from the code
17:12:11,856 TRACE [http-nio-8080-exec-2] [TransactionSynchronizationManager.java] - Clearing transaction synchronization
17:12:11,856 TRACE [http-nio-8080-exec-2] [TransactionSynchronizationManager.java] - Removed value [org.springframework.jdbc.datasource.ConnectionHolder#550de51c] for key [HikariDataSource (Hikari)] from thread [http-nio-8080-exec-2]
17:12:11,856 TRACE [http-nio-8080-exec-2] [TransactionSynchronizationManager.java] - Removed value [org.springframework.data.jpa.repository.support.CrudMethodMetadataPostProcessor$DefaultCrudMethodMetadata#6752dcc] for key [public abstract java.lang.Object org.springframework.data.repository.CrudRepository.save(java.lang.Object)] from thread [http-nio-8080-exec-2]
17:12:11,857 INFO [http-nio-8080-exec-2] [SlotConfigsController.java] - Transactional method finished
17:12:11,863 TRACE [http-nio-8080-exec-2] [TransactionSynchronizationManager.java] - Removed value [org.springframework.orm.jpa.EntityManagerHolder#4ecd9132] for key [org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean#2210e466] from thread [http-nio-8080-exec-2]
And here is the docker DB log
17:12:11.871 UTC [555] test#test LOG: execute <unnamed>: update public.slot_configs set close_time=$1 where slot_config_id=$2
17:12:11.871 UTC [555] test#test DETAIL: parameters: $1 = '1630', $2 = 5
17:12:11.877 UTC [555] test#test LOG: execute S_2: COMMIT
At 17:12:11,857 we exited the Transactional CrudRepository.save method, but the real data insertion in the DB and transaction commit happens only at 17:12:11.871 - 17:12:11.877
I supposed, that when the #Transactional method will be finished, data should be already in the DB, but looks like this action is asynchronous.
I was also trying to create a Service between controller and repository and mark the save method in the service as #Transactional(propagation = Propagation.REQUIRES_NEW), but it doesn't change anything. There is still a lag between code transactions and actual transactions in the DB.
Why does it happen? And is it possible to say Spring to wait for the DB transaction commit before exiting the #Transactional method?