@kapa.ai I use sync mode incremental+append, but when I unselected the several specific fields from one stream, the history data of those specific fields were all gone. What I expected was that history data was still there, only for the last sync, I don't receive the data from those fields?

Your observation matches how Airbyte is designed to work today. When you deselect fields in a stream and then refresh/clear that stream, Airbyte will: - Delete data in the destination for the affected streams, and - Re‑sync all historical data only for the fields that remain selected. [[Select fields](https://docs.airbyte.com/platform/using-airbyte/configuring-schema#select-fields)] Because the deselected fields are no longer part of the stream schema, their historical values are not written back during that refresh, so they appear “gone” in the destination. A few key points from the docs: - Field selection controls what is written to the destination; Airbyte may still read all fields from the source, but only selected fields are written. [[Select fields](https://docs.airbyte.com/platform/using-airbyte/configuring-schema#select-fields)] - After editing stream configuration, Airbyte recommends a refresh, which “will delete data in the destination of the affected streams and then re-sync all historical data.” [[Select fields](https://docs.airbyte.com/platform/using-airbyte/configuring-schema#select-fields)] So, with Incremental | Append, your expectation (“keep old data for deselected fields, just stop receiving them in new syncs”) is not how it behaves once you trigger a refresh/clear on that stream. The docs do not describe a built‑in way to keep historical values for deselected fields while excluding them from all future writes. If you need to preserve that history, the documented approach would be to avoid refreshing/clearing the stream after changing field selection, but the docs explicitly warn that skipping a refresh “might lead to unexpected behavior,” and they don’t detail a supported pattern for your exact use case. [[Select fields](https://docs.airbyte.com/platform/using-airbyte/configuring-schema#select-fields)]