Sequelize Migration addIndex不按降序添加索引答案

【问题标题】：Sequelize Migration addIndex not adding index in descending orderSequelize Migration addIndex不按降序添加索引
【发布时间】：2020-01-23 09:05:42
【问题描述】：

我正在尝试在日期列的现有表 (Postgres) 上创建索引，以便我可以首先获取最新帖子

模型文件 feeditem.js

module.exports = (sequelize, DataTypes) => {
  const FeedItem = sequelize.define('FeedItem', {
    feedItemId: {
      //...
    },
    pubdate: {
      allowNull: false,
      type: DataTypes.DATE,
      validate: {
        isDate: true,
        notEmpty: true,
      },
    },
    link: {
      //...
    },
    title: {
      //...
    },
    description: {
      //...
    },
    summary: {
      //...
    },
    author: {
      //...
    },
    hash: {
      //...
    },
  }, {
    timestamps: false,
    underscored: true,
    indexes: [
      {
        fields: [{ attribute: 'pubdate', order: 'DESC' }],
        unique: false,
      },
    ],
  });

  FeedItem.associate = (models) => {
    // associations can be defined here
    //...
  };
  return FeedItem;
};

迁移文件 create-feed-item.js

module.exports = {
  up: (queryInterface, Sequelize) => queryInterface.createTable('feed_items', {
    feed_item_id: {
      allowNull: false,
      autoIncrement: true,
      primaryKey: true,
      type: Sequelize.INTEGER,
    },
    pubdate: {
      allowNull: false,
      type: Sequelize.DATE,
    },
    link: {
      allowNull: false,
      type: Sequelize.STRING,
    },
    title: {
      allowNull: false,
      type: Sequelize.STRING,
    },
    description: {
      type: Sequelize.TEXT,
    },
    summary: {
      type: Sequelize.TEXT,
    },
    author: {
      type: Sequelize.STRING,
    },
    hash: {
      allowNull: false,
      type: Sequelize.UUID,
      unique: true,
    },
  }),
  // eslint-disable-next-line no-unused-vars
  down: (queryInterface, Sequelize) => queryInterface.dropTable('feed_items'),
};

迁移文件 add-index.js

module.exports = {
  /*
    Add altering commands here.
    Return a promise to correctly handle asynchronicity.
    Example:
    return queryInterface.createTable('users', { id: Sequelize.INTEGER });
  */
  // eslint-disable-next-line no-unused-vars
  up: (queryInterface, Sequelize) => queryInterface.addIndex('feed_items', ['pubdate'], {
    fields: [{
      attribute: 'pubdate', order: 'DESC',
    }],
    unique: false,
    name: 'feed_items_pubdate_index',
  }),
  /*
    Add reverting commands here.
    Return a promise to correctly handle asynchronicity.
    Example:
    return queryInterface.dropTable('users');
  */
  // eslint-disable-next-line no-unused-vars
  down: (queryInterface, Sequelize) => queryInterface.removeIndex('feed_items', 'feed_items_pubdate_index'),
};

迁移以完美的顺序运行，首先创建表，然后添加索引。日志记录已启用，当我检查日志时

预期：它应该在 pubdate 上创建一个 DESC 索引，类似于

CREATE INDEX "feed_items_pubdate_index" ON "feed_items" ("pubdate" DESC)

实际输出

Executing (default): CREATE INDEX "feed_items_pubdate_index" ON "feed_items" ("pubdate")

你知道这里出了什么问题吗？

【问题讨论】：

标签： postgresql sequelize.js database-migration

【解决方案1】：

使用唯一键：

'use strict';
module.exports = {
  up: (queryInterface, Sequelize) => {
    return queryInterface.createTable('Users', {
      id: {
        allowNull: false,
        autoIncrement: true,
        primaryKey: true,
        type: Sequelize.INTEGER
      },
      name: {
        allowNull: true,
        type: Sequelize.STRING
      },
      order: {
        allowNull: false,
        type: Sequelize.INTEGER
      },
      createdAt: {
        allowNull: false,
        type: Sequelize.DATE
      },
      updatedAt: {
        allowNull: false,
        type: Sequelize.DATE
      }
    },
    {
      uniqueKeys: {
        actions_unique: {
          fields: ["name", "order"],
        },
      },
    }
    );
  },
  down: (queryInterface, Sequelize) => {
    return queryInterface.dropTable('Users');
  }
};

【讨论】：

【解决方案2】：

您的问题仍然相关，因为它没有记录在案。

按降序定义索引的正确方法是在fields参数中扩展定义。

所以迁移文件add-index.js 应该是这样的：

module.exports = {
  ...
  up: (queryInterface, Sequelize) => queryInterface.addIndex(
    'feed_items', 
    [{
      attribute: 'pubdate', order: 'DESC',
    }], 
    {
      unique: false,
      name: 'feed_items_pubdate_index',
    }
  ),
  ...
};

已解决issue reference。

【讨论】：