---
title: "Elasticsearch"
description: "Use Elasticsearch as a vector database in Mem0 for distributed vector search using dense vectors and k-NN queries."
---
[Elasticsearch](https://www.elastic.co/) is a distributed, RESTful search and analytics engine that can efficiently store and search vector data using dense vectors and k-NN search.

### Installation

Elasticsearch support requires additional dependencies. Install them with:

```bash
pip install elasticsearch>=8.0.0
```

### Usage

```python
import os
from mem0 import Memory

os.environ["OPENAI_API_KEY"] = "sk-xx"

config = {
    "vector_store": {
        "provider": "elasticsearch",
        "config": {
            "collection_name": "mem0",
            "host": "localhost",
            "port": 9200,
            "embedding_model_dims": 1536
        }
    }
}

m = Memory.from_config(config)
messages = [
    {"role": "user", "content": "I'm planning to watch a movie tonight. Any recommendations?"},
    {"role": "assistant", "content": "How about thriller movies? They can be quite engaging."},
    {"role": "user", "content": "I’m not a big fan of thriller movies but I love sci-fi movies."},
    {"role": "assistant", "content": "Got it! I'll avoid thriller recommendations and suggest sci-fi movies in the future."}
]
m.add(messages, user_id="alice", metadata={"category": "movies"})
```

### Config

Here are the parameters available for configuring Elasticsearch:

| Parameter              | Description                                        | Default Value |
| ---------------------- | -------------------------------------------------- | ------------- |
| `collection_name`      | The name of the index to store the vectors         | `mem0`        |
| `embedding_model_dims` | Dimensions of the embedding model                  | `1536`        |
| `host`                 | The host where the Elasticsearch server is running | `localhost`   |
| `port`                 | The port where the Elasticsearch server is running | `9200`        |
| `cloud_id`             | Cloud ID for Elastic Cloud deployment              | `None`        |
| `api_key`              | API key for authentication                         | `None`        |
| `user`                 | Username for basic authentication                  | `None`        |
| `password`             | Password for basic authentication                  | `None`        |
| `use_ssl`              | Whether to use SSL for the connection              | `True`        |
| `ca_certs`             | Path to CA bundle for SSL certificate verification | `None`        |
| `verify_certs`         | Whether to verify SSL certificates                 | `True`        |
| `auto_create_index`    | Whether to automatically create the index          | `True`        |
| `custom_search_query`  | Function returning a custom search query           | `None`        |
| `headers`              | Custom headers to include in requests              | `None`        |

### Features

- Efficient vector search using Elasticsearch's native k-NN search
- Support for both local and cloud deployments (Elastic Cloud)
- Multiple authentication methods (Basic Auth, API Key)
- Automatic index creation with optimized mappings for vector search
- Memory isolation through payload filtering
- Custom search query function to customize the search query

### Custom Search Query

The `custom_search_query` parameter allows you to customize the search query when `Memory.search` is called.  
  
__Example__  
```python
import os
from typing import List, Optional, Dict
from mem0 import Memory

def custom_search_query(query: List[float], limit: int, filters: Optional[Dict]) -> Dict:
    return {
        "knn": {
            "field": "vector", 
            "query_vector": query, 
            "k": limit, 
            "num_candidates": limit * 2
        }
    }

os.environ["OPENAI_API_KEY"] = "sk-xx"

config = {
    "vector_store": {
        "provider": "elasticsearch",
        "config": {
            "collection_name": "mem0",
            "host": "localhost",
            "port": 9200,
            "embedding_model_dims": 1536,
            "custom_search_query": custom_search_query
        }
    }
}
```
It should be a function that takes the following parameters:
- `query`: a query vector used in `Memory.search`
- `limit`: a number of results used in `Memory.search`
- `filters`: a dictionary of key-value pairs used in `Memory.search`. You can add custom pairs for the custom search query.  
  
The function should return a query body for the Elasticsearch search API.