在 Django 中为 Postgres 存储生成的列创建 Gin 索引

Question

我想设置一个 Postgres "stored generated columns" with indexing to have full text search on two fields of a model. I created the generated column getting help from this tutorial，但是在列上设置 gin 索引时，我得到这个：

django.core.exceptions.FieldDoesNotExist: Article has no field named 'vector_column'. The app cache isn't ready yet, so if this is an auto-created related field, it won't be available yet.

这是我的 Article 模型：

class Article(models.Model):
    title = models.CharField(...)
    content = models.TextField(...)
    class Meta:
        indexes = [GinIndex(fields=['vector_column'])]

和我在迁移文件中的自定义 sql：

    operations = [
        migrations.RunSQL(
            sql='''
              ALTER TABLE articles_article ADD COLUMN vector_column tsvector GENERATED ALWAYS AS (
                setweight(to_tsvector('english', coalesce(title, '')), 'A') ||
                setweight(to_tsvector('english', coalesce(content,'')), 'B')
              ) STORED;
            ''',

            reverse_sql='''
              ALTER TABLE articles_article DROP COLUMN vector_column;
            '''
        ),
    ]

是否可以从 Django 设置索引？似乎 Django 需要在模型上定义字段，但这不是生成列的工作方式。如果不是，那么在迁移文件中设置正确索引的正确方法是什么（在此 Postgres doc 中提到，页面末尾的索引）？

Answer 1

正如 Iain 在评论中所说，索引必须在迁移中处理。我刚刚向 operations 数组添加了另一个迁移：

    operations = [
        migrations.RunSQL(
            sql='''
              ALTER TABLE articles_article ADD COLUMN vector_column tsvector GENERATED ALWAYS AS (
                setweight(to_tsvector('english', coalesce(title, '')), 'A') ||
                setweight(to_tsvector('english', coalesce(content,'')), 'B')
              ) STORED;
            ''',

            reverse_sql='''
              ALTER TABLE articles_article DROP COLUMN vector_column;
            '''
        ),
        migrations.RunSQL(
            sql='''
                CREATE INDEX textsearch_idx ON articles_article USING GIN (vector_column);
            ''',

            reverse_sql='''
                DROP INDEX IF EXISTS textsearch_idx;
            '''
        ),
    ]

在 Django 中为 Postgres 存储生成的列创建 Gin 索引

Creating Gin index for Postgres stored generated column in Django

django

postgresql

django-migrations