The product documentation talks about incremental ingestion via CDC using a watermark column. Are watermark columns always required for CDC? If not, how are updated rows at the source identified? Is log-based CDC supported?

Yes, Log-based CDC is supported for Oracle and SQL servers. You could refer to the below docs for the same. For the other source systems that do not support log-based CDC, you need to use watermark columns to identify the changed data and ingest it incrementally.

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