Extracting MongoDB data practices using kettle increments

Requirements : incrementally extract MongoDB data and load it into MSSQL

Due to the inability to use custom SQL for relational databases , the main problems are :

1. Query and parameter control for incremental time
2. ETL Batch information and write of call parameters

The first problem is resolved as follows :

Use named parameters to filter on the Query page , initially worrying about how ${} will be referenced using Mongo Syntax conflict , after testing found to run normally

Second question:

Add a constant value to the result first , the normal value is fixed, the direct write dead , the invariant constant value is set to an empty string , followed by the use of string replacement component passed to the named parameter , Finally, use the field selection to remove the constant value from the empty string.

Extracting MongoDB data practices using kettle increments