I have a project based on oracle-r2dbc and spring-boot-starter-data-r2dbc. I would like to execute a very simple select :

SELECT * FROM product WHERE number= 'abc222';

The column ‘number’ is an indexed column of type text.
When I run this statement in Oracle Sql Developer, the response arrives in avg time: 0.5 seconds returning 2,728 rows.

I have implemented simple repository:

public interface ProductRepository  
      extends ReactiveCrudRepository<Product, String> {
  
    @Query("SELECT * FROM product WHERE number = :number ")
    Flux<Product> findByNumber(String number);

}

I am calling this repository from a service with this code:

 return repository
                .findByNumber(number)
                .doOnSubscribe(subscription -> log.info("started, db call"))
                .doAfterTerminate(()-> log.info("finished db call")) ;

The log shows that the call took much more than I would expect:

2024-09-11T13:37:33.208+02:00 MyController : started, db call
2024-09-11T13:37:36.813+02:00 MyController : finished db call

As you see the time to process the db call takes more than 3 seconds. If I make this call many times, it is still more than 3 seconds, so we can assume its also an average time.

I would like to understand why there is such a big difference. How can I profile the whole call to see which executions consume additional time? maybe some internal processes, mapping etc. Are there any logs which I could switch on to understand what is happening under the hood?

EDIT

I have switched my stack to JDBC instead of R2DBC and the response times are much smaller. current stack is:

       <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency> 
    
        <dependency>
            <groupId>com.oracle.database.jdbc</groupId>
            <artifactId>ojdbc10</artifactId>
            <version>19.24.0.0</version>
        </dependency>

repository :

   @Query(value = "SELECT * FROM product WHERE number = :number ", nativeQuery = true)
    List<Product> find(String number );

The average time for this request is 0.8 seconds.
Still not sure why it took so long with the r2dbc approach.