# Limitations and considerations

When using ODBC as a source, the following limitations apply:

* UPDATES to primary key fields are not supported. To update the field, define it as a unique index instead.

* The ODBC Source endpoint supports full-load operations only.

* For providers that do not support batch operations, you must set the `RowByRow=true` internal parameter according to the description provided in [Internal Parameters](https://help.qlik.com/en-US/replicate/May2025/Content/Replicate/Main/ODBC/advanced_prop_odbc_source.htm#internal_parameters).

* Replicating data with 4-byte emoji characters is not supported.