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Extension descriptor (YAML)

In-process LuaJIT UDFs for DuckDB — 12 functions, JIT-compiled, GROUP BY, batch mode ~3.6x native (single-thread)

Installing and Loading

INSTALL luajit FROM community;
LOAD luajit;

Example

-- Load and compile a UDF in one shot
LOAD luajit;
SELECT message FROM luajit_module(
    mode := 'quick_compile',
    source := 'return function(x) return x * 2 + 1 end',
    sql_name := 'x2p1'
);
-- Use it immediately (auto-macro generated)
SELECT x2p1(5);
-- → 11

About luajit

luajit — JIT-compiled Lua UDFs for DuckDB

Write and run Lua functions directly in SQL. LuaJIT compiles them to native machine code with trace-based JIT, near-native performance (batch mode ~3.6× native SQL single-threaded, ~2500× faster than Python UDF).

12 Functions:

• luajit_i / luajit_f / luajit_b — typed scalar UDFs (BIGINT, DOUBLE, BOOLEAN)
• luajit_v — chunk-batched scalar (1 Lua call per chunk, ~3.6× native single-thread)
• luajit_m — mixed-type auto-cast
• luajit_l / luajit_s / luajit_map — LIST/STRUCT/MAP type bridges
• luajit_agg — aggregate UDFs with GROUP BY support
• luajit_table — table-generating UDFs
• luajit_module — module management (10 modes)

Features:

• Compile + auto-type + auto-macro in one call (quick_compile)
• Aggregate UDFs receive FULL value table, enabling median, stddev, percentile, etc.
• GROUP BY support with per-group Lua invocation
• File-based persistence (save/load) with auto-restore on LOAD
• Lua→DuckDB callback (_duckdb_call) for SQL execution from Lua
• LIST, STRUCT, MAP type bridges between DuckDB and Lua

Performance (500K rows, single-threaded):

• luajit_v (batch): 4.9ms (~3.6× native SQL)
• luajit_i (row-by-row): 24.3ms (~18× native)
• Python UDF: >160s (~200,000× native)
• Note: shared Lua state serializes under parallel execution; single-thread only

Design:

• LuaJIT 2.1 self-contained (~700KB binary)
• Zero external dependencies at runtime
• MIT licensed
• ~1050 lines of C

Platforms: Linux x64/arm64, macOS x64/arm64, Windows (MSVC). WASM excluded (LuaJIT requires GNU Make + GCC).

Added Functions

Overloaded Functions

This extension does not add any function overloads.

Added Types

This extension does not add any types.

Added Settings

This extension does not add any settings.