---
warning: DO NOT CHANGE THIS MANUALLY, THIS IS GENERATED BY https://github.com/duckdb/community-extensions repository, check README there
title: latency_injection_fs
excerpt: |
  DuckDB Community Extensions
  Used to inject simulated latency to filesystem operations

extension:
  name: latency_injection_fs
  description: Used to inject simulated latency to filesystem operations
  version: 0.2.0
  language: C++
  build: cmake
  license: MIT
  excluded_platforms: "wasm_mvp;wasm_eh;wasm_threads;windows_amd64_rtools;windows_amd64;windows_amd64_mingw"
  maintainers:
    - dentiny

repo:
  github: dentiny/duckdb-filesystem-latency-injection
  andium: a0dc5543de71f77e981f2be946ca5399db670f45
  variegata: 5f45999f1b9e62dafd48ee5f2623fec04f326dec
  ref: a062a4dd176a065671806f84e40f0280f08492c3

docs:
  hello_world: |
    SELECT * FROM latency_inject_fs_list_filesystems();
  extended_description: |
    This extension injects log-normal distribution latency to all types of filesystem operations, which could be used to local benchmark.
    It supports a few key features:
    - Supports wrapping user-requested filesystems, so users don't need to make any code change.
    - Supports simulated IO operation latency, via log-normal distribution.
    - Could be used together with rate_limit_fs to throttle operations if needed.

extension_star_count: 1
extension_star_count_pretty: 1
extension_download_count: 895
extension_download_count_pretty: 895
image: '/images/community_extensions/social_preview/preview_community_extension_latency_injection_fs.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                        |
|------------------------------------|---------------|-------------------------------------------------------------------------------------------------------------|---------|-------------------------------------------------------|
| latency_inject_fs_list_filesystems | table         | Returns the names of filesystems currently wrapped by the latency injection filesystem.                     | NULL    | [SELECT * FROM latency_inject_fs_list_filesystems();] |
| latency_inject_fs_wrap             | scalar        | Wraps a registered DuckDB filesystem with latency injection using the current latency_inject_fs_* settings. | NULL    | [SELECT latency_inject_fs_wrap('HTTPFileSystem');]    |

### 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 |
|------------------------------------------|--------------------------------------------------------------------------------------|------------|--------|---------|-------------|
| latency_inject_fs_enabled                | Enable or disable latency injection                                                  | BOOLEAN    | GLOBAL | []      | true        |
| latency_inject_fs_list_mean_ms           | Mean latency in milliseconds for LIST operations (log-normal distribution)           | DOUBLE     | GLOBAL | []      | 2.0         |
| latency_inject_fs_list_stddev            | Standard deviation for LIST operations latency (log-normal distribution)             | DOUBLE     | GLOBAL | []      | 0.5         |
| latency_inject_fs_metadata_write_mean_ms | Mean latency in milliseconds for METADATA_WRITE operations (log-normal distribution) | DOUBLE     | GLOBAL | []      | 3.0         |
| latency_inject_fs_metadata_write_stddev  | Standard deviation for METADATA_WRITE operations latency (log-normal distribution)   | DOUBLE     | GLOBAL | []      | 0.5         |
| latency_inject_fs_read_base_mean_ms      | Base mean latency in milliseconds for READ operations (log-normal distribution)      | DOUBLE     | GLOBAL | []      | 5.0         |
| latency_inject_fs_read_base_stddev       | Base standard deviation for READ operations latency (log-normal distribution)        | DOUBLE     | GLOBAL | []      | 1.0         |
| latency_inject_fs_read_bytes_per_ms      | Read throughput in bytes per millisecond (size-dependent latency)                    | DOUBLE     | GLOBAL | []      | 1000000.0   |
| latency_inject_fs_stat_mean_ms           | Mean latency in milliseconds for STAT operations (log-normal distribution)           | DOUBLE     | GLOBAL | []      | 1.0         |
| latency_inject_fs_stat_stddev            | Standard deviation for STAT operations latency (log-normal distribution)             | DOUBLE     | GLOBAL | []      | 0.3         |
| latency_inject_fs_write_base_mean_ms     | Base mean latency in milliseconds for WRITE operations (log-normal distribution)     | DOUBLE     | GLOBAL | []      | 10.0        |
| latency_inject_fs_write_base_stddev      | Base standard deviation for WRITE operations latency (log-normal distribution)       | DOUBLE     | GLOBAL | []      | 2.0         |
| latency_inject_fs_write_bytes_per_ms     | Write throughput in bytes per millisecond (size-dependent latency)                   | DOUBLE     | GLOBAL | []      | 500000.0    |
| temp_directory                           | Set the directory to which temporary files are written.                              | VARCHAR    | GLOBAL | []      | post.db.tmp |