Apache Nifi - Clickhouse : 650 million records from 9 million

[#1]

I need to copy a MS SQL table with about 9 million records to a Clickhouse database.

I did setup a QueryDatabaseTable processor to pull the table from the SQL database and a PutDatabaseRecord processor to push the records to Clickhouse db.

As long as the flowfile from the QueryDatabaseTable processor has less records than the setting of Batch Size in the PutDatabaseRecord everything works fine.

But when I have more records the PutDatabaseRecord creates multiple batches.

When I pull 30.000 records from my source table and the Batch Size is set to 10.000 I end up with 60.000 records in the destination.

Taking a look at the debug information from the PutDatabaseRecord it shows 1 insert and 3 insert batches.

When I pull all 9.5 million records I end up with 650 million records in the destination.

Any idea ?