knexjs promise release pool connection - mysql

Question

I currently use knexjs.org, promise instead of regular callback and use pool connection for SQL query. At the first time, it run smoothly. But now i usually face pool connection error. The code something like this
knex('user_detail')
.select('id','full_name','phone','email')
.where('id', id_user)
.then((result) => {
resolve(result);
})
.catch((error) => {
reject(error);
})
But now i usually get error connection timeout and error pool connection in it. The first thing why it gets an error maybe because i haven't release the connection, but i have code like this,
knex('user_detail')
.select('id','full_name','phone','email')
.where('id', id_user)
.then((result) => {
resolve(result);
})
.catch((error) => {
reject(error);
})
.finally(() => {
knex.destroy()
})
It works for the first try, but failed at second try and get an error There is no pool defined on the current client and sometimes error The pool is probably full
Can someone explain to me what's going on and how i solve it? thanks.

Answer 1

There is not enough information in question to be able to tell why you are running out of pool connections in the first place.
The way you are calling some resolve()and reject() functions gives a hunch that you are using promises inefficiently or completely wrong...
If you add complete code example how are you able to get the the pool is probably full error I can edit the answer and be able to help more. For example by creating multiple transactions by accident which are not resolved the pool will fill up.
In the second code example you are calling knex.destroy() which doesn't destroy single pool connection, but completely destroys the knex instance and the pool you are using.
So after knex.destroy() you won't be able to use that knex instance anymore and you have to create completely new instance by giving database connection configuration again.

Answer 2

This way you don't need to handle connection it will automatically commit+release to pool back on return and rollback on throw error.
const resultsAfterTransactionIsComplete = await knex.transaction(async trx => {
const result = await trx('insert-table').insert(req.list).returning('*');
// insert logs in the same transaction
const logEntries = result.map(o=> ({event_id: 1, resource: o.id}));
await trx('log-table').insert(logEntries);
// returning from transaction handler automatically commits and frees connection back to the pool
return results;
});