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OpenSearch:Service customization

Last Updated:Aug 20, 2026

Model customization allows you to fine-tune a text embedding model with your business data to enhance its performance. You can also train a custom embedding dimensionality reduction model by using vector data that you provide. In a typical business scenario, you first generate embeddings from text or queries by using a text embedding model, and then use an embedding dimensionality reduction model to reduce the dimensionality of the embeddings.

Background information

In intelligent search and RAG scenarios, vector model performance is crucial to business outcomes. However, the effectiveness of general-purpose vector models is often limited by their training data in specific domains. To improve retrieval performance, you can fine-tune a general-purpose model with your business data. Additionally, higher vector dimensionality significantly increases storage and computation costs for large-scale data. To address this, AI Search Open Platform provides an embedding dimensionality reduction service. This service allows you to train a custom model that converts high-dimensional vectors into lower-dimensional ones, helping you save costs without a significant loss in performance.

Billing

You are charged for training based on the computing units (CUs) consumed. Each CU is priced at CNY 3.87. The actual number of CUs consumed depends on the volume and dimensionality of your training data. For example, training with a minimum of 100,000 records of 1,024 dimensions consumes approximately 250 CUs, for a total cost of 250 × 3.87 = CNY 967.50.

Customize embedding dimensionality reduction

  1. In the AI Search Open Platform console, navigate to Model Service > Model Customization, and then click Create.

    A RAM user must have the required model service permissions to create a model, modify its configuration, or view its details.

  2. On the Model Customization page, configure the following parameters.

    Parameter

    Description

    Model name

    The name used to invoke the embedding dimensionality reduction service.

    Model type

    The type of model to train. Select Vector Dimensionality Reduction (embedding-dim-reduction).

    Model service

    The base model for training, such as ops-embedding-dim-reduction-001.

    Training data source

    MaxCompute or OSS

    MaxCompute data source

    Parameter

    Description

    Training data source

    MaxCompute.

    Region

    The region where your MaxCompute project is located.

    Project name

    The name of your project in MaxCompute.

    AccessKey ID

    The AccessKey ID of the Alibaba Cloud account or RAM user with read and write permissions for MaxCompute.

    You can obtain an AccessKey ID from the AccessKey Management page.

    AccessKey secret

    The AccessKey secret that corresponds to the AccessKey ID.

    Table name

    The name of the table in MaxCompute that stores your training data.

    Table partition

    The partition information of the table.

    Training fields

    To select the primary key field and String-type vector fields, grant the GetTableFields (get MaxCompute table schema) permission to the RAM user with read and write permissions on the MaxCompute table schema. The vector dimensionality must be between 1,024 and 4,096.

    OSS data source

    Parameter

    Description

    Training data source

    OSS

    Region

    The region where your OSS Bucket is located.

    OSS Bucket

    The name of your OSS Bucket.

    Doc data

    The data in OSS used for training.

    OSS Endpoint

    This value is automatically generated after you configure the preceding parameters.

  3. In the confirmation dialog, click OK. In the confirmation dialog box that appears, click Create and Train. The model enters a pre-processing state. Training starts after pre-processing is complete.

    Alternatively, click Confirm Creation. You can then find the model with the Pending Training status in the model customization list and start the training job later.

    In the model list, a model with the Available status is fully trained and ready for invocation. Click Try Now to test the performance of the fine-tuned embedding model.

Customize text embedding

  1. In the AI Search Open Platform console, navigate to Model Service > Model Customization, and then click Create.

    A RAM user must have the required model service permissions to create a model, modify its configuration, or view its details.

  2. On the Model Customization page, configure the following parameters.

    Parameter

    Description

    Model name

    A custom name for the model.

    Model type

    The type of model to train. Select Text Embedding.

    Base model

    The base model for training, such as ops-text-embedding-001.

    Embedding dimensionality reduction

    If you enable this option, an embedding dimensionality reduction training job also runs.

    Base model for dimensionality reduction

    Specifies the model for dimensionality reduction. This parameter is available only if you enable Embedding Dimensionality Reduction.

    Training data source

    MaxCompute or OSS.

    MaxCompute data source

    Parameter

    Description

    Training data source

    MaxCompute.

    Region

    The region where your MaxCompute project is located.

    Project name

    The name of your project in MaxCompute.

    AccessKey ID

    The AccessKey ID of the Alibaba Cloud account or RAM user with read and write permissions for MaxCompute.

    You can obtain an AccessKey ID from the AccessKey Management page.

    AccessKey secret

    The AccessKey secret that corresponds to the AccessKey ID.

    Table name

    The name of the table in MaxCompute that stores your training data.

    Table partition

    The partition information of the table.

    Training fields

    To select the primary key field and String-type text data, grant the GetTableFields (get MaxCompute table schema) permission to the RAM user with read and write permissions on the MaxCompute table schema.

    Query-doc pairs

    For the required data format, see the sample data in the console.

    OSS data source

    Parameter

    Description

    Training data source

    OSS

    Region

    The region where your OSS Bucket is located.

    OSS Bucket

    The name of your OSS Bucket.

    Doc data

    The data in OSS used for training.

    Query-doc pairs

    For the required data format, see the sample data in the console.

    OSS Endpoint

    This value is automatically generated after you configure the preceding parameters.

  3. Click OK. In the confirmation dialog box that appears, click Create and Train. The model enters a pre-processing state. Training starts after pre-processing is complete.

    Alternatively, click Confirm Creation. You can then find the model with the Pending Training status in the model customization list and start the training job later.

    In the model list, a model with the Available status is ready for deployment.

Service invocation

When the model's performance is satisfactory, you can invoke the service by using an API. For more information, see Embedding Dimensionality Reduction API and Custom Deployment Service API.