---
warning: DO NOT CHANGE THIS MANUALLY, THIS IS GENERATED BY https://github.com/duckdb/community-extensions repository, check README there
title: h5db
excerpt: |
  DuckDB Community Extensions
  Read HDF5 datasets and attributes

extension:
  name: h5db
  description: Read HDF5 datasets and attributes
  version: 1.4.1
  language: C++
  build: cmake
  license: MIT
  excluded_platforms: "windows_amd64_mingw;wasm_mvp;wasm_eh;wasm_threads"
  opt_in_platforms: "osx_amd64"
  requires_toolchains: "vcpkg;python3"
  maintainers:
    - jokasimr
repo:
  github: jokasimr/h5db
  ref: b4dea494155fc8c4cb20edda27f1f01dc4c8ff46
  variegata: 7de598959594ef86ccc838e64bf0e45fef315857
  andium: e185e91cca551ef31d2c19b84866cc0f462d2363

docs:
  hello_world: |
    FROM h5_read('file.h5', '/some/dataset', '/another');
  extended_description: |
    This extension provides functions for reading data and metadata from HDF5 files.

    Features include:
    - `h5_read()` table function to read datasets.
    - `h5_tree()` table function to list groups and datasets in a file, optionally including projected attributes.
    - `h5_attributes()` table function to read attributes.
    - `h5_ls()` table and scalar functions to list entries in groups.
    - Multiple datasets: Read multiple datasets into separate columns.
    - Multi-dimensional arrays: Support for 1D to 4D datasets.
    - Projection pushdown: Read only the datasets that are actually needed.
    - Index column: Optionally adds an `index` column that supports predicate pushdown of constant range filters (`>`, `<=`, `BETWEEN`, etc.) for efficient selective reads.
    - Reads datasets that are larger than memory.
    - Remote reads over HTTPS, S3, etc., via the DuckDB `httpfs` extension.
    - Remote reads over SFTP via a built-in SFTP client.
    - Globbing: Combine datasets from multiple files vertically (UNION ALL).

    For full documentation, see the [h5db repository](https://github.com/jokasimr/h5db).

extension_star_count: 6
extension_star_count_pretty: 6
extension_download_count: 853
extension_download_count_pretty: 853
image: '/images/community_extensions/social_preview/preview_community_extension_h5db.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                                     |
|---------------|---------------|------------------------------------------------------------------------------------------------------------------|---------|----------------------------------------------------------------------------------|
| h5_alias      | scalar        | Renames a column definition.                                                                                     | NULL    | [FROM h5_read('data.h5', h5_alias('temperature', '/entry/temp'))]                |
| h5_attr       | scalar        | Creates a projected HDF5 attribute definition for h5_tree() and h5_ls().                                         | NULL    | [FROM h5_tree('data.h5', h5_attr('NX_class'))]                                   |
| h5_attributes | scalar        | Reads all attributes from one HDF5 object as a MAP.                                                              | NULL    | [SELECT h5_attributes('data.h5', '/measurements')]                               |
| h5_attributes | table         | Reads all attributes from an HDF5 object or file root.                                                           | NULL    | [FROM h5_attributes('data.h5', '/measurements')]                                 |
| h5_first_file | scalar        | Returns the first concrete HDF5 filename from an exact path, glob, or list for planning-time use with h5_read(). | NULL    | [FROM h5_read(h5_first_file('runs/run_*.h5'), '/detector_geometry')]             |
| h5_index      | scalar        | Creates a virtual row-index column definition for h5_read().                                                     | NULL    | [FROM h5_read('data.h5', h5_index(), '/measurements')]                           |
| h5_ls         | scalar        | Lists entries immediately under an HDF5 group as a MAP.                                                          | NULL    | [SELECT h5_ls('data.h5', '/entry')]                                              |
| h5_ls         | table         | Lists entries immediately under an HDF5 group as rows.                                                           | NULL    | [FROM h5_ls('data.h5', '/entry')]                                                |
| h5_ls_swmr    | scalar        | Lists entries immediately under an HDF5 group as a MAP using SWMR read mode.                                     | NULL    | [SELECT h5_ls_swmr('data.h5', '/entry')]                                         |
| h5_read       | scalar        | Reads one HDF5 dataset as a VARIANT.                                                                             | NULL    | [SELECT h5_read('data.h5', '/entry/dataset')]                                    |
| h5_read       | table         | Reads one or more HDF5 datasets as DuckDB columns.                                                               | NULL    | [FROM h5_read('data.h5', '/measurements')]                                       |
| h5_ree        | scalar        | Creates a run-end encoded column definition for h5_read().                                                       | NULL    | [FROM h5_read('data.h5', '/time', h5_ree('/state_run_ends', '/state_values'))]   |
| h5_rse        | scalar        | Creates a run-start encoded column definition for h5_read().                                                     | NULL    | [FROM h5_read('data.h5', '/time', h5_rse('/state_run_starts', '/state_values'))] |
| h5_tree       | table         | Recursively lists entries in an HDF5 file.                                                                       | NULL    | [FROM h5_tree('data.h5')]                                                        |
| h5db_version  | scalar        | Returns h5db, linked HDF5, and SFTP backend library versions.                                                    | NULL    | [SELECT h5db_version()]                                                          |

### 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 |
|-------------------------------|----------------------------------------------------------------------------------|------------|--------|---------|-------------|
| h5db_batch_size               | Target batch size for h5_read read-ahead caching (e.g. 1MB, 8MB)                 | VARCHAR    | GLOBAL | []      | 1MB         |
| h5db_cache_limit_per_column   | Per-column h5_read cache limit, raised to at least four times h5db_batch_size    | VARCHAR    | GLOBAL | []      | 128MiB      |
| h5db_scalar_read_memory_limit | Estimated peak memory limit for scalar h5_read materialization (e.g. 64MB, none) | VARCHAR    | GLOBAL | []      | 64MB        |
| h5db_swmr_default             | Default to SWMR read mode for h5db table functions                               | BOOLEAN    | GLOBAL | []      | false       |
| temp_directory                | Set the directory to which temporary files are written.                          | VARCHAR    | GLOBAL | []      | post.db.tmp |