---
warning: DO NOT CHANGE THIS MANUALLY, THIS IS GENERATED BY https://github.com/duckdb/community-extensions repository, check README there
title: aixchess
excerpt: |
  DuckDB Community Extensions
  Efficiently query large chess game collections

extension:
  name: aixchess
  description: Efficiently query large chess game collections
  version: 0.3.0
  language: C++
  build: cmake
  license: GPL-3.0
  excluded_platforms: "wasm_mvp;wasm_eh;wasm_threads"
  opt_in_platforms: "windows_arm64;"
  requires_toolchains: rust
  maintainers:
    - thomas-daniels

repo:
  github: thomas-daniels/aix
  ref: 907b5107601ebe95bb4e567e0a3f4ad03afeff27

docs:
  hello_world: |
    -- Count en passant moves played in Lichess games from January 2013

    WITH lichess_2013_01 AS (
        FROM 'hf://datasets/thomasd1/aix-lichess-database/low_compression/aix_lichess_2013-01_low.parquet'
    ),
    en_passant_move_count AS (
        SELECT
            SUM(
                move_details(movedata).filter(lambda m: m.is_en_passant).length()
            ) AS nb_ep_moves 
        FROM lichess_2013_01
    )
    
    FROM en_passant_move_count;

    -- Result: 3496

  extended_description: |
    Aix enables efficient storage and querying of large chess game collections.
    A game's moves are encoded in a binary representation, and this extension
    [provides scalar functions](https://github.com/thomas-daniels/aix/blob/main/docs/functions.md) to decode and query these games directly within DuckDB.

    See the [GitHub repository](https://github.com/thomas-daniels/aix) or [blog post](https://thomasd.be/2026/02/01/aix-storing-querying-chess-games.html) for more details.
extension_star_count: 31
extension_star_count_pretty: 31
extension_download_count: 895
extension_download_count_pretty: 895
image: '/images/community_extensions/social_preview/preview_community_extension_aixchess.png'
layout: community_extension_doc
---
### Compatibility Matrix

This table covers all DuckDB releases that have not reached [end-of-life](https://duckdb.org/release_calendar), including LTS releases, and shows the 2 most recent patch releases of each. Older patch releases are not listed, but the extension may be available for them as well.

<div class="extension_compatibility_table"></div>

| Platform | 1.4.4 | 1.4.5 | 1.5.5 | 1.5.6 | 2.0.0 |
| :--- | :---: | :---: | :---: | :---: | :---: |
| Linux AMD64 | ✅ | ❌ | ✅ | ✅ | ✅ |
| Linux ARM64 | ✅ | ❌ | ✅ | ✅ | ✅ |
| macOS AMD64 | ✅ | ❌ | ✅ | ✅ | ❌ |
| macOS ARM64 | ✅ | ❌ | ✅ | ✅ | ✅ |
| Windows AMD64 | ✅ | ❌ | ✅ | ✅ | ✅ |
| Windows ARM64 | ✅ | ❌ | ✅ | ✅ | ✅ |
| WebAssembly | ❌ | ❌ | ❌ | ❌ | ❌ |

### Installing and Loading
```sql
INSTALL {{ page.extension.name }} FROM community;
LOAD {{ page.extension.name }};
```

{% if page.docs.hello_world %}
### Example
```sql
{{ page.docs.hello_world }}```
{% endif %}

{% if page.docs.extended_description %}
### About {{ page.extension.name }}
{{ page.docs.extended_description }}
{% endif %}
### Added Functions

<div class="extension_functions_table"></div>

|           function_name           | function_type |                                      description                                       | comment | examples |
|-----------------------------------|---------------|----------------------------------------------------------------------------------------|---------|----------|
| board_at_position                 | scalar        | Returns the board at a given position as a struct.                                     | NULL    | NULL     |
| clocks_to_move_times              | scalar        | Transform clocks (of one player) into move times, given the clock times and increment. | NULL    | NULL     |
| eval_to_centipawns                | scalar        | Returns eval if it is a centipawn evaluation, NULL if mate.                            | NULL    | NULL     |
| eval_to_mate                      | scalar        | Returns moves to mate if eval is mate, NULL if centipawn evaluation.                   | NULL    | NULL     |
| fen_at_position                   | scalar        | Returns the FEN at a given position.                                                   | NULL    | NULL     |
| matches_subfen                    | scalar        | Returns true if any position matches a given sub-FEN.                                  | NULL    | NULL     |
| move_details                      | scalar        | Returns a list of details for all moves in the game.                                   | NULL    | NULL     |
| move_details_at                   | scalar        | Returns the details of a given move in the game.                                       | NULL    | NULL     |
| moved_pieces                      | scalar        | Returns the moved pieces in order as a string.                                         | NULL    | NULL     |
| moved_pieces_list                 | scalar        | Returns the moved pieces in order as a list.                                           | NULL    | NULL     |
| piece_counts_at_position          | scalar        | Returns the piece counts at a given position.                                          | NULL    | NULL     |
| pieces_at_position                | scalar        | Returns the squares where the pieces are at a given position.                          | NULL    | NULL     |
| recompress                        | scalar        | Recompresses a game at a given compression level.                                      | NULL    | NULL     |
| scoutfish_query                   | scalar        | Returns true if a game matches a Scoutfish query.                                      | NULL    | NULL     |
| scoutfish_query_plies             | scalar        | Returns the list of plies matching a Scoutfish query.                                  | NULL    | NULL     |
| time_control_lichess              | scalar        | Returns the Lichess time control name for given initial time and increment.            | NULL    | NULL     |
| to_pgn                            | scalar        | Represents the game as a PGN string.                                                   | NULL    | NULL     |
| to_uci                            | scalar        | Represents the game as a UCI string.                                                   | NULL    | NULL     |
| winning_chances_lichess           | scalar        | Converts an evaluation to winning chances using the Lichess formula.                   | NULL    | NULL     |
| list_eval_to_centipawns           | macro         | Apply eval_to_centipawns to all items in a list.                                       | NULL    | NULL     |
| list_eval_to_mate                 | macro         | Apply eval_to_mate to all items in a list.                                             | NULL    | NULL     |
| list_winning_chances_lichess      | macro         | Apply winning_chances_lichess to all items in a list.                                  | NULL    | NULL     |
| is_valid_movedata                 | scalar        | NULL                                                                                   | NULL    | NULL     |
| clocks_to_move_times__check_nulls | scalar        | NULL                                                                                   | NULL    | NULL     |
| matches_fen                       | scalar        | NULL                                                                                   | NULL    | NULL     |
| move_details_ext                  | scalar        | NULL                                                                                   | NULL    | NULL     |
| move_details_ext_at               | scalar        | NULL                                                                                   | NULL    | NULL     |

### Overloaded Functions

<div class="extension_functions_table"></div>

This extension does not add any function overloads.

### Added Types

<div class="extension_types_table"></div>

This extension does not add any types.

### Added Settings

<div class="extension_settings_table"></div>

|      name      |                       description                       | input_type | scope  | aliases | typed_value |
|----------------|---------------------------------------------------------|------------|--------|---------|-------------|
| temp_directory | Set the directory to which temporary files are written. | VARCHAR    | GLOBAL | []      | post.db.tmp |