Quick Guide: Implementing Various Query Parameters in Elasticsearch with PHP for Beginners

Elasticsearch is a powerful search and analytics engine that allows for complex querying of structured and unstructured data. Integrating Elasticsearch with PHP enables efficient querying and retrieval of data based on various conditions. In this article, we’ll explore different query functionalities available in Elasticsearch using PHP, along with practical examples for each use case.

Elasticsearch Terminologies and their similar counterpart in MySQL

Understanding Elasticsearch query terminologies like must, should, bool and term with similar MySQL concepts can help in grasping how Elasticsearch structures and executes searches. Here’s an explanation of these terms and their similarities to MySQL:

must, should, and bool

In Elasticsearch, queries are typically structured using a JSON-based DSL (Domain Specific Language) that allows for complex querying capabilities. These terms are part of the bool query context, which is used for combining multiple query clauses.

must: This term is analogous to the AND operator in MySQL. It specifies that the document must match all of the specified conditions. If any condition within must clauses fails to match, the document is excluded from the result set.

should: This term is similar to the OR operator in MySQL. It represents optional clauses that are not required to match for the overall query to succeed. Documents that match any of the should clauses contribute positively to the document’s relevance score.

bool: The bool query allows for the combination of various clauses (must, should, must_not) within a single query context. It provides a flexible way to express complex boolean logic, such as combining must and should clauses together.

{
  "query": {
    "bool": {
      "must": [
        { "term": { "field1": "value1" } },
        { "range": { "field2": { "gte": 10, "lte": 20 } } }
      ],
      "should": [
        { "term": { "field3": "value3" } }
      ]
    }
  }
}

In this Elasticsearch query:

• must specifies that documents must match both field1: value1 and field2 within the range of 10 to 20.
• should specifies that documents are not required to match field3: value3, but it enhances the relevance score if they do.

term

In Elasticsearch, the term query is used to search for exact values in a specific field. It is akin to using = or IN conditions in MySQL queries.

• Exact Match: The term query matches documents where the exact value of a field matches the specified value.

{
  "query": {
    "term": { "field1": "value1" }
  }
}

This query searches for documents where field1 has exactly the value "value1".

Setting Up Elasticsearch with PHP

Before diving into query examples, ensure you have Elasticsearch installed and running. Use the official Elasticsearch PHP client (Elasticsearch-PHP) to interact with Elasticsearch in your PHP application. Below are a few more examples to understand the implementations

Multiple must (AND) Clause

Multiple should (OR) Clause

Multiple must (AND) and should (OR) Clauses

Nested should (OR) Clause inside must (AND)

Nested must (AND) Clause inside should (OR)

Below is the code where you can see the usage null check, not null check, less than, greater than, in the array etc

Conclusion

This article is a short guide for beginners starting with Elasticsearch. Elasticsearch’s query features in PHP provide flexible ways to search and filter data based on different criteria. Using the Elasticsearch-PHP client, developers can create complex queries to suit their application’s needs, from simple comparisons to more complex logical conditions. Knowing how to use these features helps developers make the most of Elasticsearch in their PHP projects.