Change Data Capture (CDC)
Change Data Capture (CDC)
Overview
Change Data Capture (CDC) files represent row-level mutations after the initial full-load snapshot.
OP Column Semantics
The OP column describes the operation type:
- I = Insert
- U = Update
- D = Delete
Reload / Replace Behavior
In some scenarios, Fortress replaces a row instead of updating it in place. In CDC, this can appear as:
Treat this sequence as a replace/upsert of the same logical record. The id remains the stable identifier.
This also explains why some D operations may not include a deletedAt value.
Processing Rules
To process CDC files correctly:
- Process files in filename order using
YYYYMMDD-HHMMSSfff.csv. - Within each file, process rows in the order provided.
- If multiple operations exist for the same
idin a batch, apply precedence:
This precedence ensures reload-style sequences resolve correctly.
Recommended Ingestion Pattern
- Start with the most recent full-load file for a topic.
- Apply CDC files in strict chronological filename order.
- Apply rows in-order within each file.
- Use operation precedence (
D -> U -> I) when multiple ops for the same id exist in one batch. - Persist checkpoints by last processed filename for resumable ingestion.

