An SQLite based, PHP-only fulltext search engine.

Loupe…

• …only requires PHP and SQLite, you don't need anything else - no containers, no nothing
• …is typo-tolerant (based on the State Set Index Algorithm and Levenshtein)
• …supports phrase search using " quotation marks
• …supports filtering (and ordering) on any attribute with any SQL-inspired filter statement
• …supports filtering (and ordering) on Geo distance
• …orders relevance based on a typical TF-IDF Cosine similarity algorithm
• …auto-detects languages
• …supports stemming
• …is very easy to use
• …is all-in-all just the easiest way to replace your good old SQL LIKE %...% queries with a way better search experience but without all the hassle of an additional service to manage. SQLite is everywhere and all it needs is your filesystem.

Introductory blog post

If this is your first encounter with Loupe, you might want to read the blog post on Medium or as Markdown file that should give you more information about the reasons and what you can do with it. Note that some implementation details (e.g. libraries used) referenced in this blog post are not up-to-date anymore.

Performance

Performance depends on many factors but here are some ballpark numbers based on indexing the ~32k movies fixture by MeiliSearch and the test files in bin of this repository:

• Indexing (php bin/index_performance_test.php) will take less than 5min (~110 documents per second)
• Querying (php bin/search_performance_test.php) for Amakin Dkywalker with typo tolerance enabled and ordered by relevance finishes in about 80 ms

Note that anything above 50k documents is probably not a use case for Loupe. Please, also read the Performance chapter in the docs. You may report your own performance measurements and more details in the respective discussion.

Acknowledgement

If you are familiar with MeiliSearch, you will notice that the API is very much inspired by it. The reasons for this are simple:

1. First and foremost: I think, they did an amazing job of keeping configuration simple and understandable from a developer's perspective. Basic search tools shouldn't be complicated.
2. If Loupe shouldn't be enough for your use case anymore (you need advanced features, better performance etc.), switching to MeiliSearch instead should be a piece of cake.

I even took the liberty to copy some of their test data to feed Loupe for functional tests.

Installation

1. Make sure you have pdo_sqlite available and your installed SQLite version is at least 3.16.0. This is when PRAGMA functions have been added without which no schema comparisons are possible. It is recommended you run at least version 3.35.0 which is when mathematical functions found its way into SQLite. Otherwise, Loupe has to polyfill those which will result in a little performance penalty.
2. Run composer require loupe/loupe.

Usage

<?php

namespace App;

require_once 'vendor/autoload.php';

use Loupe\Loupe\Config\TypoTolerance;
use Loupe\Loupe\Configuration;
use Loupe\Loupe\LoupeFactory;
use Loupe\Loupe\SearchParameters;

$configuration = Configuration::create()
    ->withPrimaryKey('uuid') // optional, by default it's 'id'
    ->withSearchableAttributes(['firstname', 'lastname']) // optional, by default it's ['*'] - everything is indexed
    ->withFilterableAttributes(['departments', 'age'])
    ->withSortableAttributes(['lastname'])
    ->withTypoTolerance(TypoTolerance::create()->withFirstCharTypoCountsDouble(false)) // can be further fine-tuned but is enabled by default
;

$loupeFactory = new LoupeFactory();

$loupe = $loupeFactory->create('path/to/my_loupe_data_dir', $configuration);

// or create in-memory search:
$loupe = $loupeFactory->createInMemory($configuration);

$loupe->addDocuments([
    [
        'uuid' => 2,
        'firstname' => 'Uta',
        'lastname' => 'Koertig',
        'departments' => [
            'Development',
            'Backoffice',
        ],
        'age' => 29,
    ],
    [
        'uuid' => 6,
        'firstname' => 'Huckleberry',
        'lastname' => 'Finn',
        'departments' => [
            'Backoffice',
        ],
        'age' => 18,
    ],
]);


$searchParameters = SearchParameters::create()
    ->withQuery('Gucleberry')
    ->withAttributesToRetrieve(['uuid', 'firstname'])
    ->withFilter("(departments = 'Backoffice' OR departments = 'Project Management') AND age > 17")
    ->withSort(['lastname:asc'])
;

$results = $loupe->search($searchParameters);

print_r($results->toArray());

/*
Array
(
    [hits] => Array
        (
            [0] => Array
                (
                    [uuid] => 6
                    [firstname] => Huckleberry
                )

        )

    [query] => Gucleberry
    [processingTimeMs] => 4
    [hitsPerPage] => 20
    [page] => 1
    [totalPages] => 1
    [totalHits] => 1
)
*/

Docs

• Schema
• Configuration
• Indexing
• Searching
• Tokenizer
• Performance

"Why Loupe?" you ask? "Loupe" means "magnifier" in French and I felt like this was the appropriate choice for this library after having given my PHP crawler library a French name :-)