Description of problem:
On a clean installation I got:

ETL service sampling has encountered an error. Please consult the service log for more details.
17/03/22 14:12:18

# journalctl -u ovirt-engine-dwhd.service
-- Logs begin at Thu 2022-03-17 08:43:47 UTC, end at Thu 2022-03-17 13:18:36 UTC. --
mar 17 09:10:55 engine.lab systemd[1]: Starting oVirt Engine Data Warehouse...
mar 17 09:10:55 engine.lab systemd[1]: Started oVirt Engine Data Warehouse.


So I assume this means /var/log/ovirt-engine-dwh/ovirt-engine-dwhd.log

At that time it shows:

2022-03-17 12:12:18|ekfouw|p8eTBV|t2mMHo|OVIRT_ENGINE_DWH|SampleTimeKeepingJob|Default|6|Java Exception|tRunJob_1|java.lang.RuntimeException:Child job running failed|1
Exception in component tJDBCInput_18
org.postgresql.util.PSQLException: ERROR: column "read_ops_per_second" does not exist
  Position: 258
        at org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:2440)
        at org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:2183)
        at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:308)
        at org.postgresql.jdbc.PgStatement.executeInternal(PgStatement.java:441)
        at org.postgresql.jdbc.PgStatement.execute(PgStatement.java:365)
        at org.postgresql.jdbc.PgStatement.executeWithFlags(PgStatement.java:307)
        at org.postgresql.jdbc.PgStatement.executeCachedSql(PgStatement.java:293)
        at org.postgresql.jdbc.PgStatement.executeWithFlags(PgStatement.java:270)
        at org.postgresql.jdbc.PgStatement.executeQuery(PgStatement.java:224)
        at ovirt_engine_dwh.statisticssync_4_5.StatisticsSync.tJDBCInput_18Process(StatisticsSync.java:13675)
        at ovirt_engine_dwh.statisticssync_4_5.StatisticsSync$7.run(StatisticsSync.java:16791)
2022-03-17 12:12:18|8jyLNz|p8eTBV|tSOBJd|OVIRT_ENGINE_DWH|StatisticsSync|Default|6|Java Exception|tJDBCInput_18|org.postgresql.util.PSQLException:ERROR: column "read_ops_per_second" does not exist
  Position: 258|1
Exception in component tRunJob_5
java.lang.RuntimeException: Child job running failed
        at ovirt_engine_dwh.samplerunjobs_4_5.SampleRunJobs.tRunJob_5Process(SampleRunJobs.java:1654)
        at ovirt_engine_dwh.samplerunjobs_4_5.SampleRunJobs.tRunJob_6Process(SampleRunJobs.java:1456)
        at ovirt_engine_dwh.samplerunjobs_4_5.SampleRunJobs.tRunJob_1Process(SampleRunJobs.java:1228)
        at ovirt_engine_dwh.samplerunjobs_4_5.SampleRunJobs.tRunJob_4Process(SampleRunJobs.java:1000)
        at ovirt_engine_dwh.samplerunjobs_4_5.SampleRunJobs.tJDBCConnection_2Process(SampleRunJobs.java:767)
        at ovirt_engine_dwh.samplerunjobs_4_5.SampleRunJobs.tJDBCConnection_1Process(SampleRunJobs.java:642)
        at ovirt_engine_dwh.samplerunjobs_4_5.SampleRunJobs$2.run(SampleRunJobs.java:2683)
2022-03-17 12:12:18|tSOBJd|p8eTBV|N1V9EF|OVIRT_ENGINE_DWH|SampleRunJobs|Default|6|Java Exception|tRunJob_5|java.lang.RuntimeException:Child job running failed|1
Exception in component tRunJob_1
java.lang.RuntimeException: Child job running failed
        at ovirt_engine_dwh.sampletimekeepingjob_4_5.SampleTimeKeepingJob.tRunJob_1Process(SampleTimeKeepingJob.java:6196)
        at ovirt_engine_dwh.sampletimekeepingjob_4_5.SampleTimeKeepingJob.tJDBCInput_2Process(SampleTimeKeepingJob.java:5938)
        at ovirt_engine_dwh.sampletimekeepingjob_4_5.SampleTimeKeepingJob.tJDBCConnection_1Process(SampleTimeKeepingJob.java:4573)
        at ovirt_engine_dwh.sampletimekeepingjob_4_5.SampleTimeKeepingJob.tJDBCConnection_2Process(SampleTimeKeepingJob.java:4448)
        at ovirt_engine_dwh.sampletimekeepingjob_4_5.SampleTimeKeepingJob.tRowGenerator_2Process(SampleTimeKeepingJob.java:4317)
        at ovirt_engine_dwh.sampletimekeepingjob_4_5.SampleTimeKeepingJob.tJDBCInput_3Process(SampleTimeKeepingJob.java:3722)
        at ovirt_engine_dwh.sampletimekeepingjob_4_5.SampleTimeKeepingJob.tJDBCInput_5Process(SampleTimeKeepingJob.java:3106)
        at ovirt_engine_dwh.sampletimekeepingjob_4_5.SampleTimeKeepingJob.tJDBCInput_4Process(SampleTimeKeepingJob.java:2424)
        at ovirt_engine_dwh.sampletimekeepingjob_4_5.SampleTimeKeepingJob.tJDBCConnection_3Process(SampleTimeKeepingJob.java:1778)
        at ovirt_engine_dwh.sampletimekeepingjob_4_5.SampleTimeKeepingJob$2.run(SampleTimeKeepingJob.java:11524)


Version-Release number of selected component (if applicable):
ovirt-engine-dwh-4.5.0-1.el8.noarch

I was adding an host to the engine, not sure it's relevant.