You can change already created EXCEL source to Excel in memory (Excel using SQLITE) without having any impact on existing catalog or rule executions. Excel in memory source uses DvSum Python service and works by creating SQLITE source for your excel file.
To change the source, first make sure DvSum Python service is running. Read here to Install and Run DvSum Python Service
From Administration > manage sources page, select the excel source and edit. Change the source type from excel to excel in memory. Save the changes.
This is it. Excel source has been changed to Excel in memory.
Upon saving, .DvSum folder containing sqlite source for this excel is created in the target folder (where your excel file is stored)
Note: Excel in memory source is independent of Java version and it will no longer user ODBC EXCEL drivers.
Specific Use Case:
A particular use case when your data source has numeric field values but you want DvSum to read it as string. For example, in the case below where you want the field value "0000000000000000043" to be read as it is and not as "43", you would have to mention the data type "str" in pre-process file. Excel in memory source requires to explicitly mention the dataType in such case.
For DvSum to read "Article_ID" as string and not as number, open pre-process propertiles file and set the dataType as "str". Save the pre-process properties files.
Once the above step is done, now you can change your excel source to excel in memory. Catalog the source and it will not truncate the leadings 0's.