在JPA + Hibernate 6中使用pgvector向量扩展

Question

使用 Spring-Boot 3 和 Hibernate 6 在 PostgreSQL 数据库中支持 pgvector 向量扩展的最佳方法是什么，这样我就可以使用 JPA 实体创建向量嵌入？

CREATE TABLE items (id bigserial PRIMARY KEY, embedding vector(5));

虽然我确实找到了适用于以前的 Hibernate 版本的解决方案，但它们不适用于 Hibernate 6，因为它需要 jakarta.persistence.* 包而不是 javax.persistence.*。我尝试使用自定义转换器类，但这没有成功（而且我什至不确定这是否是正确的方向）：

项目.java

import com.fasterxml.jackson.annotation.JsonInclude;
import jakarta.persistence.*;
import lombok.Data;
import lombok.NoArgsConstructor;
import org.springframework.data.annotation.TypeAlias;

import java.util.List;

@Data
@NoArgsConstructor
@Entity
@Table(name = "items")
@JsonInclude(JsonInclude.Include.NON_NULL)
@TypeAlias("json")
public class Item {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    @Convert(converter = VectorConverter.class)
    @Column(columnDefinition = "vector(5)")
    private List<Double> embedding;
}

VectorConverter.java：

import jakarta.persistence.AttributeConverter;
import jakarta.persistence.Converter;

import java.util.ArrayList;
import java.util.List;

@Converter
public class VectorConverter implements AttributeConverter<List<Double>, String> {

    @Override
    public String convertToDatabaseColumn(List<Double> attribute) {
        if (attribute == null || attribute.isEmpty()) {
            return "'[]'";
        }

        StringBuilder stringBuilder = new StringBuilder();
        stringBuilder.append("[");

        for (int i = 0; i < attribute.size(); i++) {
            stringBuilder.append(attribute.get(i));
            if (i < attribute.size() - 1) {
                stringBuilder.append(",");
            }
        }

        stringBuilder.append("]");
        return stringBuilder.toString();
    }

    public List<Double> convertToEntityAttribute(String dbData) {
        if (dbData == null || dbData.isEmpty()) {
            return new ArrayList<>();
        }

        String[] values = dbData.substring(1, dbData.length() - 1).split(",");

        List<Double> embeddingList = new ArrayList<>();
        for (String value : values) {
            embeddingList.add(Double.valueOf(value.trim()));
        }

        return embeddingList;
    }
}

导致以下错误：

  Hint: You will need to rewrite or cast the expression.
  Position: 39] [insert into items (embedding) values (?)]; SQL [insert into items (embedding) values (?)]] with root cause

org.postgresql.util.PSQLException: ERROR: column "embedding" is of type vector but expression is of type character varying
  Hint: You will need to rewrite or cast the expression.
  Position: 39

Answer 1

从 6.4 开始，我认为 Hibernate 发布了一个向量模块：https://docs.jboss.org/hibernate/orm/current/userguide/html_single/Hibernate_User_Guide.html#vector-module

您导入 hibernate-vector 库（您不再需要转换器），然后这应该可以工作：

@Column( name = "the_vector" )
@JdbcTypeCode(SqlTypes.VECTOR)
@Array(length = 3)
private float[] theVector;