PaulDB/docs/adr/ADR-001-htap-delta-merge.md

ADR-001: HTAP via Delta-Merge (HANA-inspired)

Status: Accepted

Decision

PaulDB implements HTAP through a Delta (Row-Store) + Main (Column-Store) split, merged periodically - mirroring SAP HANA's architecture.

Rationale

Single-store systems force a choice between OLTP and OLAP performance. The Delta-Merge pattern allows both: fast writes land in Delta (row-optimized), analytics scan Main (column-optimized, compressed).

Consequences

• Every query must union Delta + Main results.
• A merge worker must run periodically.
• The C ABI boundary (storage.h) cleanly separates both stores.