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Extension descriptor (YAML)

Native Trino-compatible scalar functions (trino_*) for the cases where DuckDB's built-ins diverge from Trino on Unicode and byte-level inputs — ICU full case folding, code-point reverse, Java-whitespace trim, NFC normalize, and raw-bytes xxhash64/sha512/hmac_sha256

Installing and Loading

INSTALL trino_parity FROM community;
LOAD trino_parity;

Example

INSTALL trino_parity FROM community;
LOAD trino_parity;

-- Full Unicode case folding, matching Trino (Java) rather than DuckDB's
-- built-in lower(). Turkish dotted-I folds to 'i' + U+0307:
SELECT trino_lower('İSTANBUL');   -- 'i̇stanbul'

-- German sharp-S upper-cases to 'SS', not U+1E9E:
SELECT trino_upper('straße');     -- 'STRASSE'

-- Code-point reverse (DuckDB's built-in reverse is grapheme-aware):
SELECT trino_reverse('a😀b');     -- 'b😀a'

-- The catalog of functions this extension provides:
SELECT trino_name, arg_count, category FROM trino_meta();  -- 10 rows

About trino_parity

trino_parity provides native trino_<name>(...) scalar functions for the specific cases where DuckDB's built-ins diverge from Trino's documented behaviour on Unicode and byte-level inputs.

It is designed to be loaded server-side by anything that pushes Trino-shaped predicates down to DuckDB. If a Trino connector naively pushes WHERE lower(name) = 'apple' down to DuckDB, the filter runs with different Unicode semantics in each engine, and rows visible to Trino can silently disappear from the result. This extension supplies only the functions where that actually happens — where DuckDB's built-in genuinely diverges and a native C++ reimplementation is required to match Trino. For the large majority of Trino functions DuckDB's built-in is already equivalent (or a trivial rename / operator / one-line rewrite), so a caller emits those directly against DuckDB — no extension needed.

Concrete divergences fixed

Function inventory

trino_meta() catalogs the ten native functions the extension provides:

• String (ICU): trino_lower/1, trino_upper/1, trino_reverse/1, trino_trim/1, trino_ltrim/1, trino_rtrim/1, trino_normalize/1 — root-locale full case folding, code-point reverse, and Character.isWhitespace trim, via statically-linked ICU vendored into the binary (so Unicode behaviour is independent of the host DuckDB build).
• Hash (vendored): trino_xxhash64/1, trino_sha512/1, trino_hmac_sha256/2 — over raw VARBINARY, self-contained (no dependency on the crypto / hashfuncs community extensions).

Aligned Trino functions (e.g. length, abs, year, substring, regexp_extract) are intentionally NOT shipped — a caller emits them as bare DuckDB SQL. The full per-function Trino↔DuckDB mapping and the empirical audits that justify each decision are in the repository's docs/.

Source and full divergence catalog: https://github.com/brikk/duckdb-trino-parity-extension

Added Functions

Overloaded Functions

This extension does not add any function overloads.

Added Types

This extension does not add any types.

Added Settings

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