Query ends, but no callback

I found a class of queries where when I run them, and they end (I’m looking in the processlist of the database) they never return any value, error, or “end” event.

This query checks if a column has all NULL values, by checking if at least one row is not NULL. If the column has all NULL values, this query never ends.

SELECT 1 FROM table WHERE column IS NOT NULL LIMIT 1

I wrapped the db query to be a promise, as well as added an “on end” callback:

  query(rawSql: string, values: any[][] = []): Promise<any[]> {
    const that = this;
    return new Promise((resolve, reject) => {
      const query = this.db.query(rawSql, values, function (err: MysqlError | null, res?: any) {
        if (err) {
            reject(err);
          } else {
            resolve(res);
          }
      });

      query.on('end', () => console.log("end"));
    });
  }

[bugfixman]

Me too occurred this error. I have 3 queries. Two queries insert and update executes in the transaction. And select query will be executed after that the transaction is completed.

After has been executed about 10 queries the function query will not called the callback. No any errors. Just the callback is not executed. Only reload the nodeJs app could help fix a bug. But after will made 10 queries the callback will not called. Have any idea?

Sorry. I’m not native speaker. I hope that not made too much mistakes.

[jarikoff]

@dougwilson Small update: once i set queueLimit: conncetionLimit - 1 to force error if queue > than possible connections - everything works good except error Queue limit reached. Expected behavior - if trying to get connections more than available - wait for released one instead of locking for no reason. I hope it will help you to make it work 😃