Една от водещите NoSQL бази данни, MongoDB е добре известна със своята бърза производителност, гъвкава схема, мащабируемост и страхотни възможности за индексиране. Нека разгледаме някакъв контекст, преди да навлезем в някои подробности. Търсенето в пълен текст е съществена функция, когато говорим за намиране на съдържание в интернет. Търсенето в Google е най-добрият пример за това, когато виждаме съдържанието, използващо фразите или ключовите думи. В тази статия ще научим за възможностите за пълнотекстово търсене в MongoDB въз основа на текстов индекс.
Създаване на примерна база данни
Преди да започнем, ще създадем примерна база данни, която ще се използва по време на урока.
Ще създадем база данни с името myDB и създайте колекция с името книги . За това изявлението ще бъде както следва.
> use myDB
> db.createCollection("books")
>Нека вмъкнем някои документи, като използваме следното изявление.
> db.books.insert([
{
"title": "Eloquent JavaScript, Second Edition",
"subtitle": "A Modern Introduction to Programming",
"author": "Marijn Haverbeke",
"publisher": "No Starch Press",
"description": "JavaScript lies at the heart of almost every modern web application, from social apps to the newest browser-based games. Though simple for beginners to pick up and play with, JavaScript is a flexible, complex language that you can use to build full-scale applications."
},
{
"title": "Learning JavaScript Design Patterns",
"subtitle": "A JavaScript and jQuery Developer's Guide",
"author": "Addy Osmani",
"publisher": "O'Reilly Media",
"description": "With Learning JavaScript Design Patterns, you'll learn how to write beautiful, structured, and maintainable JavaScript by applying classical and modern design patterns to the language. If you want to keep your code efficient, more manageable, and up-to-date with the latest best practices, this book is for you."
},
{
"title": "Speaking JavaScript",
"subtitle": "An In-Depth Guide for Programmers",
"author": "Axel Rauschmayer",
"publisher": "O'Reilly Media",
"description": "Like it or not, JavaScript is everywhere these days, from browser to server to mobile and now you, too, need to learn the language or dive deeper than you have. This concise book guides you into and through JavaScript, written by a veteran programmer who once found himself in the same position."
},
{
"title": "Programming JavaScript Applications",
"subtitle": "Robust Web Architecture with Node, HTML5, and Modern JS Libraries",
"author": "Eric Elliott",
"publisher": "O'Reilly Media",
"description": "Take advantage of JavaScript's power to build robust web-scale or enterprise applications that are easy to extend and maintain. By applying the design patterns outlined in this practical book, experienced JavaScript developers will learn how to write flexible and resilient code that's easier-yes, easier-to work with as your codebase grows."
},
{
"title": "Understanding ECMAScript 6",
"subtitle": "The Definitive Guide for JavaScript Developers",
"author": "Nicholas C. Zakas",
"publisher": "No Starch Press",
"description": "ECMAScript 6 represents the biggest update to the core of JavaScript in the history of the language. In Understanding ECMAScript 6, expert developer Nicholas C. Zakas provides a complete guide to the object types, syntax, and other exciting changes that ECMAScript 6 brings to JavaScript."
}
])Създаване на текстов индекс
Трябва да създадем текстов индекс в полетата, за да извършим текстовото търсене. Можем да създадем това в едно или няколко полета. Следното изявление ще създаде текстов индекс в едно поле.
>db.books.createIndex({"description":"text"})Ще създадем текстов индекс на описание и субтитри полета за този урок. Можем да създадем само един текстов индекс на колекция в MongoDB. Така че ще създадем съставен текстов индекс, използвайки следното изявление.
>db.books.createIndex({"subtitle":"text","description":"text"})$search
Сега ще се опитаме да търсим документи, които имат ключовите думи „ECMAScript“ в описание и субтитри полета. За това можем да използваме изявлението по-долу.
db.books.find({$text: {$search: "ECMAScript"}})Пример
>db.books.find({$text: {$search: "ECMAScript"}},{ subtitle: 1, description: 1 })
{
"_id" : ObjectId("602b09cb3cb6144ada1c62fe"),
"subtitle" : "The Definitive Guide for JavaScript Developers",
"description" : "ECMAScript 6 represents the biggest update to the core of JavaScript in the history of the language. In Understanding ECMAScript 6, expert developer Nicholas C. Zakas provides a complete guide to the object types, syntax, and other exciting changes that ECMAScript 6 brings to JavaScript."
}
>Фрази
Можете да търсите фрази с помощта на текстовия индекс. По подразбиране текстовото търсене извършва търсене ИЛИ за всички думи във фразата. Ако искате да търсите „модерен дизайн модели“, той ще търси документи с ключовите думи или модерен, дизайн, или шаблони.
Пример
>db.books.find({$text: {$search: "modern design patterns"}},{ subtitle: 1, description: 1 })
{
"_id" : ObjectId("602b098f3cb6144ada1c2ea1"),
"subtitle" : "A JavaScript and jQuery Developer's Guide",
"description" : "With Learning JavaScript Design Patterns, you'll learn how to write beautiful, structured, and maintainable JavaScript by applying classical and modern design patterns to the language. If you want to keep your code efficient, more manageable, and up-to-date with the latest best practices, this book is for you."
},
{
"_id" : ObjectId("602b09b93cb6144ada1c4bca"),
"subtitle" : "Robust Web Architecture with Node, HTML5, and Modern JS Libraries",
"description" : "Take advantage of JavaScript's power to build robust web-scale or enterprise applications that are easy to extend and maintain. By applying the design patterns outlined in this practical book, experienced JavaScript developers will learn how to write flexible and resilient code that's easier-yes, easier-to work with as your code base grows.",
},
{
"_id" : ObjectId("602b095c3cb6144ada1c1028"),
"subtitle" : "A Modern Introduction to Programming",
"description" : "JavaScript lies at the heart of almost every modern web application, from social apps to the newest browser-based games. Though simple for beginners to pick up and play with, JavaScript is a flexible, complex language that you can use to build full-scale applications."
}
>Ако искате да търсите заедно точни фрази като документи с „модерен дизайн модели“, можете да го направите, като посочите двойни кавички в текста за търсене.
Пример
>db.books.find({$text: {$search: "\"modern design patterns\""}},{ subtitle: 1, description: 1 })
{
"_id" : ObjectId("602b098f3cb6144ada1c2ea1"),
"subtitle" : "A JavaScript and jQuery Developer's Guide",
"description" : "With Learning JavaScript Design Patterns, you'll learn how to write beautiful, structured, and maintainable JavaScript by applying classical and modern design patterns to the language. If you want to keep your code efficient, more manageable, and up-to-date with the latest best practices, this book is for you."
}Отрицания
Ако искате да изключите документите, съдържащи конкретна дума, можете да използвате търсене за отрицание. Например, ако ще търсите във всички документи с „JavaScript“, но не и с „HTML5“ или „ECMAScript“, можете да търсите като примера по-долу.
Пример
>db.books.find({$text: {$search: "JavaScript -HTML5 -ECMAScript"}},{ subtitle: 1, description: 1 })
{
"_id" : ObjectId("602b098f3cb6144ada1c2ea1"),
"subtitle" : "A JavaScript and jQuery Developer's Guide",
"description" : "With Learning JavaScript Design Patterns, you'll learn how to write beautiful, structured, and maintainable JavaScript by applying classical and modern design patterns to the language. If you want to keep your code efficient, more manageable, and up-to-date with the latest best practices, this book is for you."
},
{
"_id" : ObjectId("602b09a83cb6144ada1c4973"),
"subtitle" : "An In-Depth Guide for Programmers",
"description" : "Like it or not, JavaScript is everywhere these days, from browser to server to mobile and now you, too, need to learn the language or dive deeper than you have. This concise book guides you into and through JavaScript, written by a veteran programmer who once found himself in the same position."
},
{
"_id" : ObjectId("602b095c3cb6144ada1c1028"),
"subtitle" : "A Modern Introduction to Programming",
"description" : "JavaScript lies at the heart of almost every modern web application, from social apps to the newest browser-based games. Though simple for beginners to pick up and play with, JavaScript is a flexible, complex language that you can use to build full-scale applications."
}Результат за текстово търсене
Текстовото търсене предоставя оценка за всеки документ, представяща уместността на документа със заявката за търсене. Този резултат може да се използва за сортиране на всички записи, върнати в резултата от търсенето. По-висок резултат ще покаже най-подходящото съвпадение.
Пример
>db.books.find({$text: {$search: "JavaScript "}},{score: {$meta: "textScore"}, subtitle: 1, description: 1 }).sort({score:{$meta:"textScore"}})
{
"_id" : ObjectId("602b098f3cb6144ada1c2ea1"),
"subtitle" : "A JavaScript and jQuery Developer's Guide",
"description" : "With Learning JavaScript Design Patterns, you'll learn how to write beautiful, structured, and maintainable JavaScript by applying classical and modern design patterns to the language. If you want to keep your code efficient, more manageable, and up-to-date with the latest best practices, this book is for you.",
"score" : 1.43269230769231
},
{
"_id" : ObjectId("602b09cb3cb6144ada1c62fe"),
"subtitle" : "The Definitive Guide for JavaScript Developers",
"description" : "ECMAScript 6 represents the biggest update to the core of JavaScript in the history of the language. In Understanding ECMAScript 6, expert developer Nicholas C. Zakas provides a complete guide to the object types, syntax, and other exciting changes that ECMAScript 6 brings to JavaScript.",
"score" : 1.42672413793103
},
{
"_id" : ObjectId("602b09a83cb6144ada1c4973"),
"subtitle" : "An In-Depth Guide for Programmers",
"description" : "Like it or not, JavaScript is everywhere these days, from browser to server to mobile and now you, too, need to learn the language or dive deeper than you have. This concise book guides you into and through JavaScript, written by a veteran programmer who once found himself in the same position.",
"score" : 0.818181818181818
},
{
"_id" : ObjectId("602b095c3cb6144ada1c1028"),
"subtitle" : "A Modern Introduction to Programming",
"description" : "JavaScript lies at the heart of almost every modern web application, from social apps to the newest browser-based games. Though simple for beginners to pick up and play with, JavaScript is a flexible, complex language that you can use to build full-scale applications.",
"score" : 0.801724137931034
},
{
"_id" : ObjectId("602b09b93cb6144ada1c4bca"),
"subtitle" : "Robust Web Architecture with Node, HTML5, and Modern JS Libraries",
"description" : "Take advantage of JavaScript's power to build robust web-scale or enterprise applications that are easy to extend and maintain. By applying the design patterns outlined in this practical book, experienced JavaScript developers will learn how to write flexible and resilient code that's easier-yes, easier-to work with as your codebase grows.",
"score" : 0.792857142857143
}Стоп думи
Операторът $text филтрира специфичните за езика стоп думи, като a, an, the и на английски. Търсенето по-долу няма да върне никакъв документ в резултата.
Пример
>db.books.find({$text: {$search: "is"}},{subtitle: 1, description: 1 })
Fetched 0 record(s)Стандартни думи
Операторът $text съвпада с цялата дума с основа. Така че, ако някое поле на документа съдържа думата учене или научаване, търсенето на термина обучение или научаване ще доведе до същото.
Пример
>db.books.find({$text: {$search: " learn"}},{subtitle: 1, description: 1 }) or >db.books.find({$text: {$search: " learning"}},{subtitle: 1, description: 1 })
{
"_id" : ObjectId("602b098f3cb6144ada1c2ea1"),
"subtitle" : "A JavaScript and jQuery Developer's Guide",
"description" : "With Learning JavaScript Design Patterns, you'll learn how to write beautiful, structured, and maintainable JavaScript by applying classical and modern design patterns to the language. If you want to keep your code efficient, more manageable, and up-to-date with the latest best practices, this book is for you."
},
{
"_id" : ObjectId("602b09a83cb6144ada1c4973"),
"subtitle" : "An In-Depth Guide for Programmers",
"description" : "Like it or not, JavaScript is everywhere these days, from browser to server to mobile and now you, too, need to learn the language or dive deeper than you have. This concise book guides you into and through JavaScript, written by a veteran programmer who once found himself in the same position."
},
{
"_id" : ObjectId("602b09b93cb6144ada1c4bca"),
"subtitle" : "Robust Web Architecture with Node, HTML5, and Modern JS Libraries",
"description" : "Take advantage of JavaScript's power to build robust web-scale or enterprise applications that are easy to extend and maintain. By applying the design patterns outlined in this practical book, experienced JavaScript developers will learn how to write flexible and resilient code that's easier-yes, easier-to work with as your codebase grows."
}Заключение
Надявам се днес да научите нещо ново. Ето една интересна статия за Self-Hosted MongoDB. Също така ви каня да опитате неща сами и да споделите опита си в секцията за коментари. Освен това, ако се сблъскате с някакви проблеми с някое от горните дефиниции, моля не се колебайте да ме попитате в секцията за коментари по-долу.
