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guides/retrieval.md 2026-07-14 21:58 UTC to 2026-07-15 16:58 UTC

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Retrieval

The Retrieval API allows you to perform semantic search over your data, which is a technique that surfaces semantically similar results — even when they match few or no keywords. Retrieval is useful on its own, but is especially powerful when combined with our models to synthesize responses.

Retrieval depiction

The Retrieval API is powered by vector stores, which serve as indices for your data. This guide will cover how to perform semantic search, and go into the details of vector stores.

Quickstart

  • **Create vector store** and upload files.

    • Create vector store with files

    from openai import OpenAI
client = OpenAI()

vector_store = client.vector_stores.create(        # Create vector store
    name="Support FAQ",
)

client.vector_stores.files.upload_and_poll(        # Upload file
    vector_store_id=vector_store.id,
    file=open("customer_policies.txt", "rb")
)

    import OpenAI from "openai";
const client = new OpenAI();

const vector_store = await client.vectorStores.create({   // Create vector store
    name: "Support FAQ",
});

await client.vector_stores.files.upload_and_poll({         // Upload file
    vector_store_id: vector_store.id,
    file: fs.createReadStream("customer_policies.txt"),
});
  • **Send search query** to get relevant results.

    • Search query

    user_query = "What is the return policy?"

results = client.vector_stores.search(
    vector_store_id=vector_store.id,
    query=user_query,
)

    const userQuery = "What is the return policy?";

const results = await client.vectorStores.search({
    vector_store_id: vector_store.id,
    query: userQuery,
});

    To learn how to use the results with our models, check out the synthesizing responses section.

    Semantic search is a technique that leverages vector embeddings to surface semantically relevant results. Importantly, this includes results with few or no shared keywords, which classical search techniques might miss.

    For example, let's look at potential results for "When did we go to the moon?":

    Text Keyword Similarity Semantic Similarity
    The first lunar landing occurred in July of 1969. 0% 65%
    The first man on the moon was Neil Armstrong. 27% 43%
    When I ate the moon cake, it was delicious. 40% 28%

    (Jaccard used for keyword, cosine with text-embedding-3-small used for semantic.)

    Notice how the most relevant result contains none of the words in the search query. This flexibility makes semantic search a very powerful technique for querying knowledge bases of any size.

    Semantic search is powered by vector stores, which we cover in detail later in the guide. This section will focus on the mechanics of semantic search.

    You can query a vector store using the search function and specifying a query in natural language. This will return a list of results, each with the relevant chunks, similarity scores, and file of origin.

    Search query

    results = client.vector_stores.search(
    vector_store_id=vector_store.id,
    query="How many woodchucks are allowed per passenger?",
)

    const results = await client.vectorStores.search({
    vector_store_id: vector_store.id,
    query: "How many woodchucks are allowed per passenger?",
});

    Results

    {
  "object": "vector_store.search_results.page",
  "search_query": "How many woodchucks are allowed per passenger?",
  "data": [
    {
      "file_id": "file-12345",
      "filename": "woodchuck_policy.txt",
      "score": 0.85,
      "attributes": {
        "region": "North America",
        "author": "Wildlife Department"
      },
      "content": [
        {
          "type": "text",
          "text": "According to the latest regulations, each passenger is allowed to carry up to two woodchucks."
        },
        {
          "type": "text",
          "text": "Ensure that the woodchucks are properly contained during transport."
        }
      ]
    },
    {
      "file_id": "file-67890",
      "filename": "transport_guidelines.txt",
      "score": 0.75,
      "attributes": {
        "region": "North America",
        "author": "Transport Authority"
      },
      "content": [
        {
          "type": "text",
          "text": "Passengers must adhere to the guidelines set forth by the Transport Authority regarding the transport of woodchucks."
        }
      ]
    }
  ],
  "has_more": false,
  "next_page": null
}

    A response will contain 10 results maximum by default, but you can set up to 50 using the max_num_results param.

    Query rewriting

    Certain query styles yield better results, so we've provided a setting to automatically rewrite your queries for optimal performance. Enable this feature by setting rewrite_query=true when performing a search.

    The rewritten query will be available in the result's search_query field.

    Original Rewritten
    I'd like to know the height of the main office building. primary office building height
    What are the safety regulations for transporting hazardous materials? safety regulations for hazardous materials
    How do I file a complaint about a service issue? service complaint filing process

    Attribute filtering

    Attribute filtering helps narrow down results by applying criteria, such as restricting searches to a specific date range. You can define and combine criteria in attribute_filter to target files based on their attributes before performing semantic search.

    Use comparison filters to compare a specific key in a file's attributes with a given value, and compound filters to combine multiple filters using and and or.

    Comparison filter

    {
  "type": "eq" | "ne" | "gt" | "gte" | "lt" | "lte" | "in" | "nin",  // comparison operators
  "key": "attributes_key",                           // attributes key
  "value": "target_value"                             // value to compare against
}

    Compound filter

    {
  "type": "and" | "or",                                // logical operators
  "filters": [...]                                   
}

    Below are some example filters.

    Filter for a region 
    {
  "type": "eq",
  "key": "region",
  "value": "us"
}

    Ranking

    If you find that your file search results are not sufficiently relevant, you can adjust the ranking_options to improve the quality of responses. This includes specifying a ranker, such as auto or default-2024-08-21, and setting a score_threshold between 0.0 and 1.0. A higher score_threshold will limit the results to more relevant chunks, though it may exclude some potentially useful ones. When ranking_options.hybrid_search is provided you can also tune hybrid_search.embedding_weight (rrf_embedding_weight) and hybrid_search.text_weight (rrf_text_weight) to control how reciprocal rank fusion balances semantic embedding matches vs. sparse keyword matches. Increase the former to emphasize semantic similarity, increase the latter to emphasize textual overlap, and ensure at least one of the weights is greater than zero.

    Vector stores

    Vector stores are the containers that power semantic search for the Retrieval API and the file search tool. When you add a file to a vector store it will be automatically chunked, embedded, and indexed.

    Vector stores contain vector_store_file objects, which are backed by a file object.

    <div style={{ minWidth: '150px', whiteSpace: 'nowrap' }}>Object type Description
    file Represents content uploaded through the Files API. Often used with vector stores, but also for fine-tuning and other use cases.
    vector_store Container for searchable files.
    vector_store.file Wrapper type specifically representing a file that has been chunked and embedded, and has been associated with a vector_store.
    Contains attributes map used for filtering.

    Pricing

    You will be charged based on the total storage used across all your vector stores, determined by the size of parsed chunks and their corresponding embeddings.

    Storage Cost
    Up to 1 GB (across all stores) Free
    Beyond 1 GB $0.10/GB/day

    See expiration policies for options to minimize costs.

    Vector store operations

    Create vector store 
    client.vector_stores.create(
    name="Support FAQ",
    file_ids=["file_123"]
)

    await client.vector_stores.create({
    name: "Support FAQ",
    file_ids: ["file_123"]
});

    Vector store file operations

    Some operations, like create for vector_store.file, are asynchronous and may take time to complete — use our helper functions, like create_and_poll to block until it is. Otherwise, you may check the status. Removing files from a vector store is eventually consistent, and search results may still include content from a removed file for a short period.

    Adding files is rate limited per vector store ID. Requests to /vector_stores/{vector_store_id}/files and /vector_stores/{vector_store_id}/file_batches share a per-vector-store limit of 300 requests per minute.

    Create vector store file 
    client.vector_stores.files.create_and_poll(
    vector_store_id="vs_123",
    file_id="file_123"
)

    await client.vector_stores.files.create_and_poll({
    vector_store_id: "vs_123",
    file_id: "file_123"
});

    Batch operations

    Batch create operation 
    client.vector_stores.file_batches.create_and_poll(
    vector_store_id="vs_123",
    files=[
        {
            "file_id": "file_123",
            "attributes": {"department": "finance"}
        },
        {
            "file_id": "file_456",
            "chunking_strategy": {
                "type": "static",
                "max_chunk_size_tokens": 1200,
                "chunk_overlap_tokens": 200
            }
        }
    ]
)

    await client.vector_stores.file_batches.create_and_poll({
    vector_store_id: "vs_123",
    files: [
        {
            file_id: "file_123",
            attributes: { department: "finance" }
        },
        {
            file_id: "file_456",
            chunking_strategy: {
                type: "static",
                max_chunk_size_tokens: 1200,
                chunk_overlap_tokens: 200
            }
        }
    ]
});

    When creating a batch you can either provide file_ids with optional attributes and/or chunking_strategy, or use the files array to pass objects that include a file_id plus optional attributes and chunking_strategy for each file. The two options are mutually exclusive so that you can cleanly control whether every file shares the same settings or you need per-file overrides.

    For higher-throughput ingestion into a single vector store, we recommend batch creation whenever possible. Batches can include up to 500 files in one request, which usually reduces contention and improves end-to-end latency versus sending many single-file create requests.

    Attributes

    Each vector_store.file can have associated attributes, a dictionary of values that can be referenced when performing semantic search with attribute filtering. The dictionary can have at most 16 keys, with a limit of 256 characters each.

    Create vector store file with attributes

    client.vector_stores.files.create(
    vector_store_id="<vector_store_id>",
    file_id="file_123",
    attributes={
        "region": "US",
        "category": "Marketing",
        "date": 1672531200      # Jan 1, 2023
    }
)

    await client.vector_stores.files.create(<vector_store_id>, {
    file_id: "file_123",
    attributes: {
        region: "US",
        category: "Marketing",
        date: 1672531200, // Jan 1, 2023
    },
});

    Expiration policies

    You can set an expiration policy on vector_store objects with expires_after. Once a vector store expires, all associated vector_store.file objects will be deleted and you'll no longer be charged for them.

    Set expiration policy for vector store

    client.vector_stores.update(
    vector_store_id="vs_123",
    expires_after={
        "anchor": "last_active_at",
        "days": 7
    }
)

    await client.vector_stores.update({
    vector_store_id: "vs_123",
    expires_after: {
        anchor: "last_active_at",
        days: 7,
    },
});

    Limits

    The maximum file size is 512 MB. Each file should contain no more than 5,000,000 tokens per file (computed automatically when you attach a file).

    Chunking

    By default, max_chunk_size_tokens is set to 800 and chunk_overlap_tokens is set to 400, meaning every file is indexed by being split up into 800-token chunks, with 400-token overlap between consecutive chunks.

    You can adjust this by setting chunking_strategy when adding files to the vector store. There are certain limitations to chunking_strategy:

    • max_chunk_size_tokens must be between 100 and 4096 inclusive.
    • chunk_overlap_tokens must be non-negative and should not exceed max_chunk_size_tokens / 2.

    Supported file types

    For text/ MIME types, the encoding must be one of utf-8, utf-16, or ascii.

    {/* Keep this table in sync with RETRIEVAL_SUPPORTED_EXTENSIONS in the agentapi service */}

    File format MIME type
    .c text/x-c
    .cpp text/x-c++
    .cs text/x-csharp
    .css text/css
    .doc application/msword
    .docx application/vnd.openxmlformats-officedocument.wordprocessingml.document
    .go text/x-golang
    .html text/html
    .java text/x-java
    .js text/javascript
    .json application/json
    .md text/markdown
    .pdf application/pdf
    .php text/x-php
    .pptx application/vnd.openxmlformats-officedocument.presentationml.presentation
    .py text/x-python
    .py text/x-script.python
    .rb text/x-ruby
    .sh application/x-sh
    .tex text/x-tex
    .ts application/typescript
    .txt text/plain

    Synthesizing responses

    After performing a query you may want to synthesize a response based on the results. You can leverage our models to do so, by supplying the results and original query, to get back a grounded response.

    Perform search query to get results

    from openai import OpenAI

client = OpenAI()

user_query = "What is the return policy?"

results = client.vector_stores.search(
    vector_store_id=vector_store.id,
    query=user_query,
)

    import OpenAI from "openai";
const client = new OpenAI();

const userQuery = "What is the return policy?";

const results = await client.vectorStores.search({
    vector_store_id: vector_store.id,
    query: userQuery,
});

    Synthesize a response based on results

    formatted_results = format_results(results.data)

'\n'.join('\n'.join(c.text) for c in result.content for result in results.data)

completion = client.chat.completions.create(
    model="gpt-5.6",
    messages=[
        {
            "role": "developer",
            "content": "Produce a concise answer to the query based on the provided sources."
        },
        {
            "role": "user",
            "content": f"Sources: {formatted_results}\n\nQuery: '{user_query}'"
        }
    ],
)

print(completion.choices[0].message.content)

    const formattedResults = formatResults(results.data);
// Join the text content of all results
const textSources = results.data.map(result => result.content.map(c => c.text).join('\n')).join('\n');

const completion = await client.chat.completions.create({
    model: "gpt-5.6",
    messages: [
        {
            role: "developer",
            content: "Produce a concise answer to the query based on the provided sources."
        },
        {
            role: "user",
            content: `Sources: ${formattedResults}\n\nQuery: '${userQuery}'`
        }
    ],
});

console.log(completion.choices[0].message.content);

    "Our return policy allows returns within 30 days of purchase."

    This uses a sample format_results function, which could be implemented like so:

    Sample result formatting function

    def format_results(results):
    formatted_results = ''
    for result in results.data:
        formatted_result = f"<result file_id='{result.file_id}' file_name='{result.file_name}'>"
        for part in result.content:
            formatted_result += f"<content>{part.text}</content>"
        formatted_results += formatted_result + "</result>"
    return f"<sources>{formatted_results}</sources>"

    function formatResults(results) {
    let formattedResults = '';
    for (const result of results.data) {
        let formattedResult = `<result file_id='${result.file_id}' file_name='${result.file_name}'>`;
        for (const part of result.content) {
            formattedResult += `<content>${part.text}</content>`;
        }
        formattedResults += formattedResult + "</result>";
    }
    return `<sources>${formattedResults}</sources>`;
}