Load types
A load type determines what happens to the existing data in the target table during a load. You set it per table (and can override it per run with an alternative load).
| Load type | What it does | History? |
|---|---|---|
| FULL | Replaces existing records with new ones. | No |
| DELTA | Compares old and new data and only adds changed records. | Yes (via staging) |
| OVERWRITE | Deletes all existing records and adds all new ones. | No |
| RELOAD | Like FULL, but with optimized updates that do not replace unchanged data. | Keeps unchanged |
| IMAGE | Does not replace/reload, but keeps a record of older data. | Yes |
| ADDITIONAL | Adds new records without replacing existing ones. | Yes (append only) |
| Delta Image (v1.53+) | Selectively reloads a period (e.g. last year), removes outdated records from that period and keeps the remaining history. | Yes (per period) |
Which load type when?
- FULL / OVERWRITE — small tables or tables to be fully refreshed; no history needed.
- DELTA — large tables with a reliable change column; process only changes.
- RELOAD — reload the full set but avoid unnecessary writes (and therefore cost/time).
- IMAGE — when you want to keep historical snapshots.
- ADDITIONAL — append-only sources (logs, events).
- Delta Image — periodically reload a defined period (e.g. fiscal-year corrections).
Related settings
- Key columns — uniquely identify records when column positions may change. For SQL sources (except MySQL), two delta columns are possible (comma-separated in
LoadManagement.UsedTables.deltaColumn, same data type — the highest value counts). - Staging (
DefaultKeepStage) — for delta loads, a staging table that is truncated or kept after processing. - Surrogate keys (
DefaultSurrogate) — automatically generated keys on the natural key (stored in[LoadManagement].[SurrogateKeys]). - Pagination (
UsePagination/PageSize) — process large datasets (100M+ records) in pages.
See also Connecting & loading a data source and the glossary.