Dyamic table name for JPQL / Hibernate query

Question

I've a database with many thousands of tables that have been (and continue to be) created with a naming strategy - one table per calendar day:

• data_2010_01_01
• data_2010_01_02
• ...
• data_2020_01_01

All tables contain sensor data from the same system in the same shape. So a single entity (lets call it SensorRecord) will absolutely map to all tables.

I'd imagined something like this would work:

@Query(nativeQuery = true, value = "SELECT * FROM \"?1\"")
Collection<SensorRecord> findSensorDataForDate(String tableName);

But it does not, and reading around the topic seems to suggest I am on the wrong path. Most posts on dynamic naming seem to state explicitly that you need one entity per table, but generating thousands of duplicate entities also seems wrong.

How can I use JPA (JPQL?) to work with this data where the table name follows a naming convention and can be changed as part of the query?

Answer 1

Parameters are only allowed in the where clause. You can create custom repository method returns collection of SensorRecord dto. No need to map so many entities. You should get List<Object []> as query result and manually create dto objects.

    @Autowired 
    EntityManager entityManager;    

    public List<SensorRecord> findSensorDataForDate(LocalDate date) {
           DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy_MM_dd");
           String tableName = "data_" + date.format(formatter);

           Query query = entityManager.createNativeQuery(
                             "select t.first_column, t.second_column from " + tableName + " t");

           List<Object[]> queryResults = query.getResultList();

           List<SensorRecord> sensorRecords = new ArrayList<>();
           for (Object[] row : queryResults) {
               SensorRecord record = new SensorRecord();
               record.setFirstParameter((Integer) row[0]);
               record.setSecondParameter((String) row[1]);

               sensorRecords.add(record);
           }

           return sensorRecords;
   }

Answer 2

Could it be just syntax error?

This has worked for me:

    @Query(value = "select * from job where job.locked = 1 and job.user = ?1", nativeQuery = true)
    public List<JobDAO> getJobsForUser(@Param("user") String user);