duckdb-knowledge-patch

DuckDB Knowledge Patch

Use this skill when writing DuckDB SQL, upgrading an existing database, working with external files or lakehouse formats, configuring the CLI, or using spatial data. Inspect the project's DuckDB version and load the relevant topic reference before relying on defaults, return types, parser behavior, storage compatibility, or extension behavior.

How to apply this skill

1. Determine the exact DuckDB library, CLI, and extension versions in use.
2. Review the compatibility checks below before changing existing SQL or files.
3. Treat database storage versions separately from the engine version.
4. Check extension and platform requirements before generating deployment steps.
5. Load the topic reference that matches the task; it contains the complete semantics and directional caveats behind the quick reference.
6. Prefer project manifests, code, tests, and observed behavior if the project is newer than the frontmatter version.

Reference index

Reference	Topics
Compatibility and migrations	Release-line support, changed SQL behavior, parser changes, deprecations, upgrade checks
SQL and types	VARIANT, maps, date_trunc, UNPACK, secrets, direct database scans
Storage, security, and remote files	Storage versions, encryption, compression, external cache, CSV, Azure, httpfs
Lakehouses and connectors	DuckLake, Delta, Iceberg, ODBC, Teradata, database-wide copies
CLI and platforms	Previous results, safe mode, direct file opening, installation, Linux requirements
Spatial and geometry	Axis-order migration, core GEOMETRY, CRS typing, WKB boundaries

Compatibility checks first

Account for changed SQL results and types

• date_trunc on a DATE returns TIMESTAMP. Add an explicit cast when an application, schema, or client contract still requires DATE.
• map['key'] returns the value itself and is equivalent to map_extract_value. Use map_extract only when the required result is a single-element list.
• current_time and current_date use the local timezone and require ICU.
• A fixed random seed does not reproduce sequences from engines that used the earlier generator state.
• Nested-structure serialization escapes quotes so values round-trip. Use array_to_string when code deliberately needs the old unquoted display.