I recently refactored code for getting posts from a Postgres database from this:

const getPostByPk = async (token, post_id) => {
  const requestor_id = await verifyToken(token)

  const post = await Posts.findByPk(post_id, { raw: true });

  const isLiked = await Likes.findOne({
    where: {
      [Op.and]: [{ user_id: requestor_id }, { post_id: post_id }],
    },
  });
  
  return {
    ...post,
    isLiked: isLiked != null,
    isAuthor: (user_id == requestor_id),
  };
};

const getPostByLoc = async (token, college) => {
  const post_ids = await Posts.findAll({
    where: {
      college: college,
      public: true
    },
    attributes: ["post_id"],
  })

  const posts = await Promise.all(
    post_ids.map((post) => getPostByPk(token, post.post_id))
  );

  return posts;

};

This became painfully slow after more than a few hundred posts, so I switched to eager loading w/ sequelize associations:

async function getCleanedPosts(requester_id, queryObject) {
    const posts = await Posts.findAll({
      where: queryObject,
      include: [
        {
          model: User,
        },
        {
          model: Loops,
          required: false
        },
        {
          model: Likes,
          where: {
            user_id: requester_id
          },
          required: false 
        }
      ]
    });


    return posts.map(post => {
        const {torus_user, like_relationships, loop, ...cleanedPost} = post.toJSON()

        const isLiked = like_relationships.length > 0;

        return {
          ...cleanedPost,
          isLiked,
          loop_name: loop?.name,
          loop_id: loop?.loop_id,
          isAuthor: torus_user.user_id === requester_id,
        };
    });
}

Though this is much faster, I’m now often encountering some pretty unsettling errors with just a few active users at a time.

ConnectionAcquireTimeoutError [SequelizeConnectionAcquireTimeoutError]: Operation timeout
Causes all requests to fail often but then goes away after a few minutes or a restart

I tried updating the Sequelize pool configuration

const sequelize = new Sequelize(
  process.env.DB_DATABASE,
  process.env.DB_USERNAME,
  process.env.DB_PASSWORD,
  {
    host: process.env.DB_HOST,
    dialect: "postgres",
    pool: {
      max: 30,
      min: 0,
      acquire: 60000,
      idle: 10000
    }
  },

);

But this just caused numerous ConnectionError [SequelizeConnectionError]: remaining connection slots are reserved for non-replication superuser connections errors

Any help is much appreciated!