---
categories:
- docs
- develop
- stack
- oss
- rs
- rc
- oss
- kubernetes
- clients
description: Learn how to use the Redis query engine with JSON and hash documents.
linkTitle: Index and query documents
title: Index and query documents
scope: example
relatedPages:
- /develop/clients/php/vecsearch
- /develop/ai/search-and-query
topics:
- Redis Query Engine
- JSON
- hash
weight: 20
---

This example shows how to create a
[search index]({{< relref "/develop/ai/search-and-query/indexing" >}})
for [JSON]({{< relref "/develop/data-types/json" >}}) documents and
run queries against the index. It then goes on to show the slight differences
in the equivalent code for [hash]({{< relref "/develop/data-types/hashes" >}})
documents.

{{< note >}}From [v3.0.0](https://github.com/predis/predis/releases/tag/v3.0.0) onwards,
`Predis` uses query dialect 2 by default.
Redis query engine methods such as [`ftSearch()`]({{< relref "/commands/ft.search" >}})
will explicitly request this dialect, overriding the default set for the server.
See
[Query dialects]({{< relref "/develop/ai/search-and-query/advanced-concepts/dialects" >}})
for more information.
{{< /note >}}

## Initialize

Make sure that you have [Redis Open Source]({{< relref "/operate/oss_and_stack/" >}})
or another Redis server available. Also install the
[`Predis`]({{< relref "/develop/clients/php" >}}) client library if you
haven't already done so.

Add the following dependencies:

{{< clients-example set="php_home_json" step="import" description="Foundational: Import required dependencies for Redis query engine and JSON operations" difficulty="beginner" >}}
{{< /clients-example >}}

## Create data

Create some test data to add to your database:

{{< clients-example set="php_home_json" step="create_data" description="Foundational: Create sample JSON data structures for indexing and querying" difficulty="beginner" >}}
{{< /clients-example >}}

## Add the index

Connect to your Redis database. The code below shows the most
basic connection but see
[Connect to the server]({{< relref "/develop/clients/php/connect" >}})
to learn more about the available connection options.

{{< clients-example set="php_home_json" step="connect" description="Foundational: Connect to a Redis server and establish a client connection" difficulty="beginner" >}}
{{< /clients-example >}}

Create an
[index]({{< relref "/develop/ai/search-and-query/indexing" >}}).
In this example, only JSON documents with the key prefix `user:` are indexed.
For more information, see
[Query syntax]({{< relref "/develop/ai/search-and-query/query/" >}}).

{{< clients-example set="php_home_json" step="make_index" description="Foundational: Create a search index for JSON documents with field schema and prefix filtering" difficulty="intermediate" >}}
{{< /clients-example >}}

## Add the data

Add the three sets of user data to the database as
[JSON]({{< relref "/develop/data-types/json" >}}) objects.
If you use keys with the `user:` prefix then Redis will index the
objects automatically as you add them:

{{< clients-example set="php_home_json" step="add_data" description="Foundational: Store JSON documents with indexed key prefixes for automatic indexing" difficulty="beginner" >}}
{{< /clients-example >}}

## Query the data

You can now use the index to search the JSON objects. The
[query]({{< relref "/develop/ai/search-and-query/query" >}})
below searches for objects that have the text "Paul" in any field
and have an `age` value in the range 30 to 40:

{{< clients-example set="php_home_json" step="query1" description="Query data: Execute full-text and range queries on indexed JSON documents using FT.SEARCH" difficulty="intermediate" >}}
{{< /clients-example >}}

Specify query options to return only the `city` field:

{{< clients-example set="php_home_json" step="query2" description="Restrict query results: Use query options to return specific fields from search results" difficulty="intermediate" >}}
{{< /clients-example >}}

Use an
[aggregation query]({{< relref "/develop/ai/search-and-query/query/aggregation" >}})
to count all users in each city.

{{< clients-example set="php_home_json" step="query3" description="Aggregation: Use aggregation queries to group and count results from indexed documents" difficulty="advanced" >}}
{{< /clients-example >}}

## Differences with hash documents

Indexing for hash documents is very similar to JSON indexing but you
need to specify some slightly different options.

When you create the schema for a hash index, you don't need to
add aliases for the fields, since you use the basic names to access
the fields anyway. Also, you must use `HASH` for the `On()` option
when you create the index. The code below shows these changes with
a new index called `hash-idx:users`, which is otherwise the same as
the `idx:users` index used for JSON documents in the previous examples.

{{< clients-example set="php_home_json" step="make_hash_index" description="Foundational: Create a search index for hash documents with HASH type specification" difficulty="intermediate" >}}
{{< /clients-example >}}

You use [`hmset()`]({{< relref "/commands/hset" >}}) to add the hash
documents instead of [`jsonset()`]({{< relref "/commands/json.set" >}}).
Supply the fields as an array directly, without using
[`json_encode()`](https://www.php.net/manual/en/function.json-encode.php).

{{< clients-example set="php_home_json" step="add_hash_data" description="Foundational: Store hash documents using HSET for indexed retrieval" difficulty="beginner" >}}
{{< /clients-example >}}

The query commands work the same here for hash as they do for JSON (but
the name of the hash index is different). The format of the result is
almost the same except that the fields are returned directly in the
result array rather than in a JSON string with `$` as its key:

{{< clients-example set="php_home_json" step="query1_hash" description="Query data: Query hash documents using the same search syntax as JSON with different result formatting" difficulty="intermediate" >}}
{{< /clients-example >}}

## More information

See the [Redis query engine]({{< relref "/develop/ai/search-and-query" >}}) docs
for a full description of all query features with examples.