This page describes what is supported in DuckDB and DuckLake in relation to DuckDB standalone (i.e., :memory: or DuckDB file modes). We can make a distinction between:

• What is currently not supported by the DuckLake specification. These are features that you are supported by DuckDB when using DuckDB's native database format but will not work with a DuckLake backend since the specification does not support them.

• What is currently not supported by the ducklake DuckDB extension. These are features that are supported by the DuckLake specification but are not (yet) implemented in the DuckDB extension.

Unsupported by the DuckLake Specification

Within this group, we are going to make a distinction between what is not supported now but is likely to be supported in the future and what is not supported and is unlikely to be supported.

Likely to be Supported in the Future

• User defined types

• Geometry/Geospatial types

• Fixed-size arrays, i.e., ARRAY type

• Variant types

• CHECK constraints. Not to be confused with Primary or Foreign Key constraint.

• Scalar and table macros. However, if the catalog DB supports it, there is a workaround.

    -- Using DuckDB as a catalog, create the macro in the catalog
    USE __ducklake_metadata_my_ducklake;
    CREATE MACRO add_and_multiply(a, b, c) AS (a + b) * c;
  
    -- Use the macro to create a table in DuckLake
    CREATE TABLE my_ducklake.table_w_macro AS
        SELECT add_and_multiply(1, 2, 3) AS col;
  

• Default values that are not literals. See the following example:

    -- This is allowed
    CREATE TABLE t1 (id INTEGER, d DATE DEFAULT '2025-08-08');
  
    -- This is not allowed
    CREATE TABLE t1 (id INTEGER, d DATE DEFAULT now());
  

• Dropping dependencies, such as views, when calling DROP ... CASCADE. Note that this is also a DuckDB limitation.

• Generated columns

Unlikely to be Supported in the Future

• Indexes

• Primary key or enforced unique constraints and foreign key constraints are unlikely to be supported as these are constraints are prohibitively expensive to enforce in data lake setups. We may consider supporting unenforced primary keys, similar to BigQuery's implementation.

• Sequences

• VARINT type

• BITSTRING type

• UNION type

Unsupported by the ducklake DuckDB Extension

The following features are currently unsupported by the ducklake DuckDB extension:

• Data inlining is limited to DuckDB catalogs

• MySQL catalogs are not fully supported in the DuckDB extension

• Updates that target the same row multiple times