Welcome to Apache Lucene.NET

Powerful Full-text search for .NET

Apache Lucene.NET is an open-source full-text search library written in C#. It is a port of the popular Java Apache Lucene project.

Apache Lucene.NET is a .NET library providing powerful indexing and search features, as well as spellchecking, hit highlighting and advanced analysis/tokenization capabilities.

Lucene.NET version 4.8 (still in Beta) runs everywhere .NET runs, including Windows, Unix, MacOS, Android and iOS.

The Apache Lucene.NET website is at: http://lucenenet.apache.org

Supported Frameworks

Lucene.NET 3.0.3

• .NET Framework 4.0
• .NET Framework 3.5

Lucene.NET 4.8.0

• .NET 6.0
• .NET Standard 2.1
• .NET Standard 2.0
• .NET Framework 4.5

Status

Latest Release Version: Lucene.NET 3.0.3

Working toward Lucene.NET 4.8.0 (currently in BETA)

• The beta version is extremely stable
• Has more than 7800+ passing unit tests
• Integrates well with .NET 6.0, .NET 5.0 and .NET Core 2+
• Supports .NET Standard 2.1 and .NET Standard 2.0
• Supports .NET Framework 4.5+
• Some developers already use it in production environments

Download

Lucene.NET 3.0.3

Core Library

PM> Install-Package Lucene.Net

All Packages

• Lucene.Net - Core library
• Lucene.Net.Contrib - Various user contributed functionality and extras
• Lucene.Net.Contrib.Spatial - Geospatial Search
• Lucene.Net.Contrib.Spatial.NTS - Geospatial search with support for NetTopologySuite.

Lucene.NET 4.8.0

Core Library

PM> Install-Package Lucene.Net -Pre

All Packages

• Lucene.Net - Core library
• Lucene.Net.Analysis.Common - Analyzers for indexing content in different languages and domains
• Lucene.Net.Analysis.Kuromoji - Japanese Morphological Analyzer
• Lucene.Net.Analysis.Morfologik - Analyzer for dictionary stemming, built-in Polish dictionary
• Lucene.Net.Analysis.OpenNLP - OpenNLP Library Integration
• Lucene.Net.Analysis.Phonetic - Analyzer for indexing phonetic signatures (for sounds-alike search)
• Lucene.Net.Analysis.SmartCn - Analyzer for indexing Chinese
• Lucene.Net.Analysis.Stempel - Analyzer for indexing Polish
• Lucene.Net.Benchmark - System for benchmarking Lucene
• Lucene.Net.Classification - Classification module for Lucene
• Lucene.Net.Codecs - Lucene codecs and postings formats
• Lucene.Net.Expressions - Dynamically computed values to sort/facet/search on based on a pluggable grammar
• Lucene.Net.Facet - Faceted indexing and search capabilities
• Lucene.Net.Grouping - Collectors for grouping search results
• Lucene.Net.Highlighter - Highlights search keywords in results
• Lucene.Net.ICU - Specialized ICU (International Components for Unicode) Analyzers and Highlighters
• Lucene.Net.Join - Index-time and Query-time joins for normalized content
• Lucene.Net.Memory - Single-document in-memory index implementation
• Lucene.Net.Misc - Index tools and other miscellaneous code
• Lucene.Net.Queries - Filters and Queries that add to core Lucene
• Lucene.Net.QueryParser - Text to Query parsers and parsing framework
• Lucene.Net.Replicator Files replication utility
• Lucene.Net.Sandbox - Various third party contributions and new ideas
• Lucene.Net.Spatial - Geospatial search
• Lucene.Net.Suggest - Auto-suggest and Spell-checking support
• Lucene.Net.TestFramework - Framework for testing Lucene-based applications

Documentation

We have preliminary documentation for Lucene.NET 4.8.0 on the Lucene.NET Website.

The API is similar to Java Lucene 4.8.0, which you may also find helpful to review.

NOTE: We are working on fixing issues with the documentation, but could use more help since it is a massive project. See #206.

Legacy Versions

• Lucene.Net 3.0.3 API Documentation
• Lucene.Net 2.9.4 API Documentation

Demos & Tools

There are several demos implemented as simple console applications that can be copied and pasted into Visual Studio or compiled on the command line in the Lucene.Net.Demo project.

There is also a dotnet command line tool available on NuGet. It contains all of the demos as well as tools maintaining your Lucene.NET index, featuring operations such as splitting, merging, listing segment info, fixing, deleting segments, upgrading, etc. Always be sure to back up your index before running any commands against it!

• Prerequisite: .NET 6.0 Runtime or Higher

dotnet tool install lucene-cli -g --version 4.8.0-beta00015

NOTE: The version of the CLI you install should match the version of Lucene.NET you use.

Once installed, you can explore the commands and options that are available by entering the command lucene.

lucene-cli Documentation

How to Contribute

We love getting contributions! Read our Contribution Guide or read on for ways that you can help.

Join Mailing Lists

How to Join Mailing Lists

Ask a Question

If you have a general how-to question or need help from the Lucene.NET community, please subscribe to the user mailing list by sending an email to [email protected] and then follow the instructions to verify your email address. Note that you only need to subscribe once.

After you have subscribed to the mailing list, email your message to [email protected].

Alternatively, you can get help via StackOverflow's active community.

Please do not submit general how-to questions to GitHub, use GitHub for bug reports and tasks only.

Report a Bug

To report a bug, please use the GitHub issue tracker.

NOTE: In the past, the Lucene.NET project used the JIRA issue tracker, which has now been deprecated. However, we are keeping it active for tracking legacy issues. Please submit any new issues to GitHub.

Start a Discussion

To start a development discussion regarding the technical features of Lucene.NET, please email the dev mailing list by sending an email to [email protected] and then follow the instructions to verify your email address. Note that you only need to subscribe once.

After you have subscribed to the mailing list, email your message to [email protected].

Submit a Pull Request

Before you start working on a pull request, please read our Contributing guide.

Building and Testing

Command Line

Prerequisites

1. PowerShell 5.0 or higher (see this question to check your PowerShell version)
2. .NET 7.0 SDK or higher

Execution

NOTE: If the project is open in Visual Studio, its background restore may interfere with these commands. It is recommended to close all instances of Visual Studio that have Lucene.Net.sln open before executing.

To build the source, clone or download and unzip the repository. For specific releases, download and unzip the .src.zip file from the download page of the specific version. From the repository or distribution root, execute the build command from a command prompt and include the desired options from the build options table below:

Windows

> build [options]

Linux or macOS

./build [options]

NOTE: The build file will need to be given permission to run using the command chmod u+x build before the first execution.

Build Options

The following options are case-insensitive. Each option has both a short form indicated by a single - and a long-form indicated by --. The options that require a value must be followed by a space and then the value, similar to running the dotnet CLI.

For example, the following command creates a Release build with NuGet package version 4.8.0‑ci00015 and file version 4.8.0. The assembly version will be derived from the major version component of the passed in value, excluding the minor, build and revision components (in this case 4.0.0).

Windows

> build ‑‑configuration Release ‑pv 4.8.0‑ci00015 ‑fv 4.8.0

Linux or macOS

./build ‑‑configuration Release ‑pv 4.8.0‑ci00015 ‑fv 4.8.0

In the above example, we are using "ci" in the package version to indicate this is not a publicly released beta version but rather the output of a continuous integration build from master which occurred after beta00014 but before beta00015 was released.

NuGet packages are output by the build to the /_artifacts/NuGetPackages/ directory. Test results (if applicable) are output to the /_artifacts/TestResults/ directory.

You can setup Visual Studio to read the NuGet packages like any NuGet feed by following these steps:

1. In Visual Studio, right-click the solution in Solution Explorer, and choose "Manage NuGet Packages for Solution"
2. Click the gear icon next to the Package sources dropdown.
3. Click the + icon (for add)
4. Give the source a name such as Lucene.Net Local Packages
5. Click the ... button next to the Source field, and choose the /src/_artifacts/NuGetPackages folder on your local system.
6. Click Ok

Then all you need to do is choose the Lucene.Net Local Packages feed from the dropdown (in the NuGet Package Manager) and you can search for, install, and update the NuGet packages just as you can with any Internet-based feed.

Visual Studio

Prerequisites

1. Visual Studio 2022 or higher
2. .NET 7.0 SDK or higher

Execution

1. Open Lucene.Net.sln in Visual Studio.
2. Choose the target framework to test by opening .build/TestTargetFramework.props and uncommenting the corresponding <TargetFramework> (and commenting all others).
3. Build a project or the entire solution, and wait for Visual Studio to discover the tests - this may take several minutes.
4. Run or debug the tests in Test Explorer, optionally using the desired filters.

NOTE: When running tests in Visual Studio, be sure to set the default processor architecture to 64 bit to avoid running out of virtual memory on some tests.

Azure DevOps

We have setup our azure-pipelines.yml file with logical defaults so anyone with an Azure DevOps account can build Lucene.NET and run the tests with minimal effort. Even a free Azure DevOps account will work, but tests will run much faster if the account is setup as public, which enables up to 10 parallel jobs to run simultaneously.

Prerequisites

1. An Azure DevOps account.
2. A fork of this repository either on GitHub or Azure DevOps. The rest of these instructions assume a GitHub fork.

Execution

If you don't already have a pipeline set up:

1. Create an Azure DevOps organization. If you already have one that you wish to use, you may skip this step.
2. Create an Azure DevOps project. We recommend naming the project Lucene.NET. Note that if you are using a free Azure DevOps account, you should choose to make the project public in order to enable 10 parallel jobs. If you make the project private, you will only get 1 parallel job. Also, if disabling features, make sure to leave Pipelines enabled.
3. Create an Azure DevOps pipeline.
   • Click on "Pipelines" from the left menu.
   • Click the "Create Pipeline" or "New Pipeline" button, depending on whether any pipelines already exist.
   • Select GitHub as the location to find the YAML file.
   • Select the fork of this repository you created in "Prerequisites". Note that if this is a new Azure DevOps account you may need to setup extra permissions to access your GitHub account.
   • Next a "Review your YAML" page is presented showing the contents of azure-pipelines.yml. There is documentation near the top of the file indicating the variables that can be setup to enable additional options, but note that the default configuration will automatically run the build and all of the tests.
   • Click the "Run" button at the top right of the page.

If you already have a pipeline set up:

1. Click on "Pipelines" from the left menu.
2. Select the pipeline you wish to run.
3. Click the "Queue" button on the upper right.
4. (Optional) Select the branch and override any variables in the pipeline for this run.
5. Click the "Run" button.

Note that after the build is complete, the nuget artifact contains .nupkg files which may be downloaded to your local machine where you can setup a local folder to act as a NuGet feed.

It is also possible to add an Azure DevOps feed id to a new variable named ArtifactFeedID, but we are getting mixed results due to permission issues.