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MySQL vs Alopex DB

MySQL's VECTOR type, vector functions, and embedded library status. Also explains how it differs from Alopex DB.

Updated: Oct 12, 2026

What MySQL is

MySQL is a server-based relational database. It has a VECTOR type.

How it works

  • VECTOR type: elements are 4-byte floating-point numbers. The default is 2048 elements and the maximum is 16383.
  • Vector functions: there are four: DISTANCE(), STRING_TO_VECTOR(), VECTOR_DIM(), and VECTOR_TO_STRING().
  • HNSW index: from 9.5.0, MySQL HeatWave GenAI automatically creates indexes such as HNSW on frequently queried VECTOR columns in vector store and embedding tables. The HeatWave vector store ingests documents from Object Storage.
  • MySQL HeatWave: a fully managed cloud service. It consists of a DB System running MySQL Enterprise Edition and a HeatWave Cluster that holds data in memory in a hybrid columnar format and processes it in parallel. It is available on OCI, AWS, and Azure.

Main features

SQL tables can hold VECTOR columns. HeatWave GenAI provides an HNSW vector index.

Limits

  • A VECTOR column cannot be a primary key, foreign key, unique key, or partition key.
  • A VECTOR column cannot be an argument to numeric, JSON, or full-text functions. COUNT [DISTINCT] is the only aggregate or window function it supports.
  • The embedded server library libmysqld was removed in 8.0.1. The replacement is a standalone mysqld server with libmysqlclient.
  • HeatWave’s vector store and automatic HNSW indexes are features of the MySQL HeatWave cloud service.

How it differs from Alopex DB

Both can hold vectors in SQL tables.

Alopex DB has the vector type and HNSW index in the core. Choose the distance from cosine, L2, and inner product. It embeds in your application as a single file. When you need a server, the same file opens in the HTTP and gRPC server.

Alopex DB embeds in the app and runs vector search in the core. Give it a try for your next app, starting with the quickstart.

References