API Reference

Note

The C++ APIs of the Index SDK feature retrieval component follow the exception handling mechanism of the open-source Faiss API. Therefore, you must call them within try/catch blocks and handle exceptions there. For a detailed example, see the handling method in Code Reference. This prevents program exits caused by exceptions during use.

Note

• Because some feature retrieval inputs use pointer types, ensure that these pointers are valid. Otherwise, potential issues such as out-of-bounds reads or writes may occur during feature retrieval. In addition, feature retrieval helps the Ascend AI Processor perform vector retrieval computation, so you must ensure that the input Device ID is valid. Otherwise, the function may fail because the device connection fails.
• Faiss is a widely used vector retrieval acceleration library in the industry. To help ecosystem users quickly migrate vector retrieval clustering services from CPU/GPU platforms to the Ascend platform, the AscendIndex base class for many algorithms on the Ascend platform inherits from the faiss::Index class. The member variables d and ntotal in faiss::Index are public. When you use AscendIndex and its AscendIndexInt8 subclasses, do not modify these public member variables directly.
• This document no longer describes the member functions and variables of the base class faiss::Index.
• For the resourceSize variable in the Config class, its purpose is to reserve memory for intermediate results during feature retrieval. The unit is bytes. You are advised to increase it when the base-library features are large, for example, more than 3 million, and the number of query requests is large. This helps avoid performance fluctuations caused by temporary memory allocation during retrieval. You are advised to set it to 1024 * 1024 * 1024 bytes.
• When you create a new Index, the system compares it with the requested resources. If there is a difference, it releases the original memory resources and requests new ones according to the latest Index resources. You are advised to keep the overall resources value of the Index consistent.
• You can set the operator execution timeout by setting the MX_INDEX_SYNCHRONIZE_STREAM_TIME environment variable. The unit is ms, and the value range is [60000, 1800000]. The default value is 300000.

Note

${mxIndex_install_path} indicates the installation path of Index SDK.