Overview
| Property | Value |
|---|
| Engine ID | duckdb |
| Wire Protocol | pgwire (exposed by Mori) |
| Classifier | Regex-based |
| Shadow | Local file copy (full data, not schema-only) |
| Docker Required | No |
The shadow is a full copy of the production database file, including all data. For large analytical databases, be aware of disk space implications.
| Field | Description |
|---|
file_path | Path to the DuckDB file |
mori init --from "/path/to/analytics.duckdb"
mori init --from "duckdb:///path/to/analytics.duckdb"
Differences from PostgreSQL
- Full file copy shadow — Complete copy of the production database including all data. The prod file is opened with
access_mode=READ_ONLY, providing database-level write protection.
- Regex-based classification — Handles DuckDB-specific constructs:
INSERT OR REPLACE, INSERT OR IGNORE, CREATE OR REPLACE TABLE, DESCRIBE, PRAGMA, INSTALL, LOAD, QUALIFY.
rowid for PK-less tables — Uses DuckDB’s implicit rowid column for deduplication.- JOIN via materialization — Dirty tables are materialized into temp tables on shadow, the JOIN SQL is rewritten to reference them, and DuckDB handles the JOIN natively.
- Aggregate via materialization — All aggregates (COUNT, SUM, AVG, MIN, MAX, GROUP BY, list(), array_agg, etc.) use materialization — base data is merged into a temp table, then DuckDB handles aggregation natively. This plays to DuckDB’s strengths as an analytical engine.
- WHERE clause evaluator — Regex-based with DuckDB fallback: constructs
SELECT 1 WHERE <condition> on shadow for complex expressions.
- DuckDB type mapping — Maps DuckDB types to PostgreSQL OIDs for pgwire compatibility. Nested types (LIST, STRUCT, MAP, UNION) map to JSON OID. Unsigned integers map to the next larger signed PostgreSQL type.
INSERT OR REPLACE for hydration — DuckDB-specific upsert semantics for hydrating prod rows into shadow.- No Docker required — Shadow is a local file copy.
- No cursor support — Cursors are not classified or handled.
- No LISTEN/UNLISTEN — Not applicable to DuckDB.
Known Limitations
- No cursor operations.
- DuckDB-specific SQL syntax not parseable by
pg_query_go — but DuckDB uses its own regex classifier, so this is handled.
LIST() / ARRAY_AGG() results serialize as JSON through pgwire (nested types).- Unsupported operations: COPY/EXPORT/IMPORT, EXPLAIN ANALYZE.
