---
title: Db2 Vector Search Tool
description: Semantic vector search for CrewAI agents using IBM Db2 native VECTOR_DISTANCE capabilities.
icon: database
mode: "wide"
---

# `DB2VectorSearchTool`

## Description

Perform semantic vector similarity searches against IBM Db2 tables using the native `VECTOR_DISTANCE` function.
Supports configurable distance metrics, OpenAI or custom embeddings, metadata filtering, and result shaping.

## Installation

```bash
pip install ibm_db openai
```

Or with uv:

```bash
uv add ibm_db openai
```

## Environment Variables

```bash
OPENAI_API_KEY=your_openai_key          # Required when using default OpenAI embeddings
DB2_CONNECTION_STRING=DATABASE=TESTDB;HOSTNAME=localhost;PORT=50000;PROTOCOL=TCPIP;UID=db2user;PWD=password;
```

## Basic Usage

```python
from crewai import Agent
from crewai_tools import DB2VectorSearchTool

tool = DB2VectorSearchTool(
    connection_string="DATABASE=TESTDB;HOSTNAME=localhost;PORT=50000;PROTOCOL=TCPIP;UID=db2user;PWD=password;",
    table_name="documents",
    vector_column="embedding",
)

agent = Agent(
    role="Research Assistant",
    goal="Find relevant information in documents",
    tools=[tool],
)
```

## Full Semantic Search Workflow

```python
import os
from dotenv import load_dotenv
from crewai import Agent, Task, Crew, Process
from crewai_tools import DB2VectorSearchTool

load_dotenv()

db2_tool = DB2VectorSearchTool(
    connection_string=os.getenv("DB2_CONNECTION_STRING"),
    table_name="documents",
    vector_column="embedding",
    return_columns=["content", "category"],
    limit=3,
    distance_metric="COSINE",
    max_distance=0.35,
)

search_agent = Agent(
    role="Senior Semantic Search Agent",
    goal="Find and analyse documents based on semantic search",
    backstory="You are an expert research assistant who can find relevant information using semantic search in a Db2 database.",
    tools=[db2_tool],
    verbose=True,
)

answer_agent = Agent(
    role="Senior Answer Assistant",
    goal="Generate answers based on retrieved context",
    backstory="You are an expert assistant who generates answers from provided context.",
    tools=[db2_tool],
    verbose=True,
)

search_task = Task(
    description="""Search for relevant documents about {query}.
    Include the relevant information found, vector distances, and returned fields.""",
    agent=search_agent,
)

answer_task = Task(
    description="Given the retrieved Db2 context, generate a final answer.",
    agent=answer_agent,
)

crew = Crew(
    agents=[search_agent, answer_agent],
    tasks=[search_task, answer_task],
    process=Process.sequential,
    verbose=True,
)

result = crew.kickoff(inputs={"query": "What is the role of X in the document?"})
print(result)
```

## Tool Parameters

| Parameter | Type | Default | Description |
|---|---|---|---|
| `connection_string` | `str` | required | Db2 connection string. Format: `DATABASE=x;HOSTNAME=x;PORT=50000;PROTOCOL=TCPIP;UID=x;PWD=x;` |
| `table_name` | `str` | `"documents"` | Table to search. Supports `schema.table` notation. |
| `vector_column` | `str` | `"embedding"` | Column storing the vector embeddings. |
| `embedding_model` | `str` | `"text-embedding-3-large"` | OpenAI model used when no custom embedding function is provided. |
| `return_columns` | `list[str]` | `["content"]` | Columns to include in each result. Must contain at least one entry. |
| `limit` | `int` | `3` | Maximum number of results (1–100). |
| `distance_metric` | `str` | `"COSINE"` | Db2 distance metric. See supported values below. |
| `max_distance` | `float \| None` | `None` | Drop results whose distance exceeds this value. |
| `custom_embedding_fn` | `Callable[[str], list[float]] \| None` | `None` | Custom embedding function. Overrides OpenAI when provided. |

## Supported Distance Metrics

The following values map directly to the Db2 `VECTOR_DISTANCE` function:

- `COSINE`
- `EUCLIDEAN`
- `EUCLIDEAN_SQUARED`
- `DOT`
- `HAMMING`
- `MANHATTAN`

Reference: [IBM Db2 VECTOR_DISTANCE documentation](https://www.ibm.com/docs/en/db2/12.1.x?topic=functions-vector-distance)

## Schema Parameters (per query)

| Parameter | Type | Required | Description |
|---|---|---|---|
| `query` | `str` | ✅ | The search query. |
| `filter_by` | `str \| None` | ❌ | Column name for metadata filtering. Must be paired with `filter_value`. |
| `filter_value` | `Any \| None` | ❌ | Value to filter on. Must be paired with `filter_by`. |

## Return Format

```json
{
  "success": true,
  "results": [
    {
      "distance": 0.1401,
      "data": {
        "content": "Document content here",
        "category": "research"
      }
    }
  ]
}
```

On error:

```json
{
  "success": false,
  "error": "Description of what went wrong",
  "error_type": "ExceptionClassName"
}
```

## Metadata Filtering

```python
result = db2_tool.run(
    query="machine learning",
    filter_by="category",
    filter_value="research",
)
```

`filter_by` and `filter_value` must always be provided together. Providing only one raises a validation error.

## Custom Embeddings

Use any embedding model by supplying a `custom_embedding_fn`:

```python
from sentence_transformers import SentenceTransformer
from crewai_tools import DB2VectorSearchTool

model = SentenceTransformer("sentence-transformers/all-MiniLM-L6-v2")

def custom_embeddings(text: str) -> list[float]:
    return model.encode(text).tolist()

tool = DB2VectorSearchTool(
    connection_string="DATABASE=TESTDB;HOSTNAME=localhost;PORT=50000;PROTOCOL=TCPIP;UID=db2user;PWD=password;",
    table_name="documents",
    custom_embedding_fn=custom_embeddings,
)
```

When `custom_embedding_fn` is provided, `OPENAI_API_KEY` is not required.

## Security Features

- SQL identifier validation (table, column names must match `^[A-Za-z][A-Za-z0-9_]*(\.[A-Za-z][A-Za-z0-9_]*)?$`)
- Parameterised SQL queries — values never interpolated into SQL strings
- Distance metric whitelist — only valid Db2 metric names accepted
