Show HN: hlquery, An open-source C++20 search engine

Hlquery, an open-source C++20 search engine, is now available on GitHub under an unstable branch, offering full-text search, hybrid ranking, vector similarity, and AI-assisted search via a REST API and command-line tools. The project is in active development and not recommended for production use, with a live demo at demo.hlquery.com. It targets teams needing lightweight, efficient search with low operational overhead.

Development Status: hlquery is currently in active development and should not be used in production environments. The software may contain bugs and incomplete features, and breaking changes may occur without notice. You can explore the live demo at demo.hlquery.com . It runs on the m demo.cpp module, which disables insert, delete, and update operations in demo mode. The demo UI is built with hanalyzer . hlquery is an open-source C++ search engine built to stay lightweight while handling millions of results efficiently. It targets applications that need fast indexing, real-time queries, and a straightforward HTTP/JSON interface with advanced search features. The engine supports full-text search, hybrid ranking, vector similarity, flexible collections, and configurable runtime modules for features such as AI-assisted search. It also includes a REST API for indexing and querying, plus command-line tools for local management and testing. hlquery is built for teams that want strong search without the operational weight of a larger stack. It combines fast indexing, low-latency queries, and a simple HTTP/JSON API with features usually found in more complex systems. You can use hlquery for full-text search, hybrid retrieval, vector similarity, and AI-assisted workflows while keeping deployment straightforward. It ships with client libraries, command-line tools, and modular runtime extensions for local development and production services. hlquery organizes data into collections . A collection is a logical group of related records, such as products, articles, users, or events, and its schema defines the fields that can be indexed, searched, filtered, sorted, or used for faceting. Each collection contains documents . A document is a JSON record identified by a unique ID and made up of fields such as title , content , category , or price . Documents in the same collection follow the same general schema, while each document stores its own values. For example, a products collection can contain one document per product. You can then search the text fields, filter by structured fields such as category or price, and return only the fields needed by your application. Collections keep different types of data organized while allowing each type to have its own schema and search behavior. Debian/Ubuntu: bash $ sudo apt-get install build-essential cmake zlib1g-dev libssl-dev liburing-dev cmake and zlib1g-dev are required to configure and build hlquery and its bundled RocksDB dependency on Debian/Ubuntu. The ./configure script validates CMake, GNU Make, the C++ compiler, and zlib headers/linking, and exits with an installation hint when a requirement is missing. If CMake prints a uring lookup warning during the rocksdb build, it usually means the liburing development package is missing. Installing liburing-dev on Debian/Ubuntu provides the package metadata CMake is looking for and clears the warning. Red Hat/CentOS: bash $ sudo dnf install @development-tools cmake openssl-devel macOS: bash $ xcode-select --install $ brew install cmake openssl On macOS, Xcode Command Line Tools provide the C/C++ compiler and make . Homebrew provides CMake and OpenSSL. FreeBSD: bash $ sudo pkg install gmake cmake openssl Note : This project uses gmake features. On FreeBSD, run gmake instead of make . bash $ wget https://github.com/hlquery/hlquery/archive/refs/heads/unstable.zip $ cd hlquery/ $ ./configure On GNU/Linux: bash $ make -j4 $ make install On FreeBSD, use GNU make for the build and install steps: bash $ gmake -j4 $ gmake install Start the server $ ./run/hlquery start OK Starting hlquery: Jul-12 - 12:37:59 ... Note: hlquery uses port9200by default. Ensure this port is available and not blocked by your firewall. Stop the server $ ./run/hlquery stop INFO Stopping hlquery PID: 27008 ... OK hlquery stopped successfully. Stop the server as JSON $ ./run/hlquery stop --json {"action":"stop","stopped pid":206773,"success":true} Run in foreground for debugging : $ ./run/hlquery start --nofork ... Run the interactive shell $ ./run/hlquery talk localhost:9200 use art Using collection 'art'. Checking uptime's localhost:9200|art uptime Server up for 3 days, 1h 0m 31s Official client libraries are available for popular programming languages: | Client | Description | |---|---| | Native C++ client library for low-level and embedded integrations. | | Go client for indexing, search, and service backends. | | JVM client for Java applications and server-side integrations. | | Async JavaScript client for Node.js services and tools. | | Perl client library for scripts and existing Perl services. | | Composer-ready PHP client for web apps and API integrations. | | Python client for scripts, data workflows, and backend services. | | Ruby client for Rails apps, scripts, and service integrations. | | Rust client library for strongly typed hlquery integrations. | | Typed client for TypeScript applications and SDK-style integrations. | For complete API documentation, visit docs.hlquery.com https://docs.hlquery.com/ . $ ./run/hlquery cli create products title content price Collection 'products' created successfully Using the PHP API: php <?php require once DIR . '/vendor/autoload.php'; use Hlquery\Client; $client = new Client 'http://localhost:9200' ; $collections = $client- collections ; $schema = 'fields' = 'name' = 'title', 'type' = 'string' , 'name' = 'content', 'type' = 'string' , 'name' = 'sku', 'type' = 'keyword' , 'name' = 'price', 'type' = 'float' , , ; $response = $collections- create 'products', $schema ; $body = $response- getBody ; echo json encode $body, JSON PRETTY PRINT . PHP EOL; $client- documents- add 'products', 'id' = 'prod keyboard 001', 'title' = 'Wireless Keyboard', 'content' = 'Compact Bluetooth keyboard for daily work.', 'price' = 49.99, ; Each document ID must be unique within its collection: bash $ hlquery-cli add products prod laptop 001 "Laptop Computer" "High-performance laptop with 16GB RAM" Document 'prod laptop 001' added to collection 'products' Using the Node API js const Client = require 'hlquery-node-client' ; const client = new Client 'http://localhost:9200' ; const documents = client.documents ; // Use the documents service for document writes. / Send POST /collections/products/documents with the product payload. / const response = await documents.add 'products', { id: 'prod laptop 001', title: 'Laptop Computer', content: 'High-performance laptop with 16GB RAM', price: 1299.99 } ; / Inspect the JSON body returned by the API. / console.log response.getBody ; bash $ hlquery-cli search products "laptop" Search results for 'laptop' in collection 'products': Found 1 document s showing 1-1 of 1 +---+-----------------+----------+-----------------+---------------------------------------+ | | Document ID | Score | Title | Content Preview | +---+-----------------+----------+-----------------+---------------------------------------+ | 1 | prod laptop 001 | 1.094500 | Laptop Computer | High-performance laptop with 16GB RAM | +---+-----------------+----------+-----------------+---------------------------------------+ Using the C++ API include "hlquery/client.h" hlquery::Client client "http://localhost:9200" ; auto collections = client.collections ; auto result = collections- search "products", {{"like", "laptop"}} ; Field-specific search $ ./run/hlquery cli search products "title:laptop" Range query $ ./run/hlquery cli search products "price: 100 TO 500 " Fuzzy search tolerates typos $ ./run/hlquery cli search products "laptop~2" Wildcard search $ ./run/hlquery cli search products "laptop " Case-sensitive search $ ./run/hlquery cli search products "is:casesensitive Laptop" Boost term importance $ ./run/hlquery cli search products "laptop^2.0 computer" NOT operator $ ./run/hlquery cli search products " apple" Combined queries $ ./run/hlquery cli search products "title:laptop AND price: 100 TO 500 " hlquery supports linking two or more servers together. Links are configured in links.conf with <node ... entries and can be used for distributed queries, write replication, or both by listing the same remote endpoint with the role needed for each purpose. Distributed search fans a query out to linked search nodes and merges the results. Use role="distributed" for query peers and enable <distributed search ... : <node host="127.0.0.1" port="9201" role="distributed" passwd="shared-secret" <distributed search enabled="true" mode="local first" prefer local="true" timeout ms="250" SQL example: $ ./run/hlquery talk localhost:9200 sql: select title from music where content like 'madon%' or content like 'nirva%'; SQL rows for select title from music where content like 'madon%' or content like 'nirva%'; : +-------------------------+ | title | +-------------------------+ | Artist Profile: Madonna | | Artist Profile: Nirvana | +-------------------------+ 2 results shown. Search completed in 19 ms. Runtime links use the same role split. Use role="master" or distributed for a query link and role="slave" or replica for a replication target. If the link is authenticated, include token and optionally token2 in the JSON body; runtime-added links are in-memory and must be added again after restart: POST /links/connect {"host":"127.0.0.1","port":9202,"role":"slave","token":"shared-secret"} hlquery is actively developed across multiple GitHub repositories. We maintain a structured development workflow to ensure stability and continuous improvement. Each repository follows a two-branch development model : - Active development branch where new features, bug fixes, and improvements are developed unstable - Stable release branch containing production-ready code 1.0 We are committed to active, continuous development of hlquery and all related projects. New features, performance improvements, and bug fixes are regularly added across all repositories. Want to stay updated? ⭐ Star and watch our repositories on GitHub to receive notifications about: - New releases and features - Bug fixes and improvements - Documentation updates - Community discussions Subscribe to repository notifications to never miss an update We welcome contributions from the community All contributions must be released under the BSD 3-Clause license. - Check existing issues https://github.com/hlquery/hlquery/issues or open a new one. - Contribute to client libraries. - Test and report bugs. - Improve documentation. - 📖 Documentation https://docs.hlquery.com - 🐦 X Twitter https://x.com/hlquery - 📦 GitHub https://github.com/hlquery/hlquery hlquery is licensed under the BSD 3-Clause License https://opensource.org/licenses/BSD-3-Clause .