mysqljs/mysql

Connection error details with a pool cluster with canRetry=true

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#1612 opened on Dec 26, 2016

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help wanted

Description

When using pool cluster with canRetry=true, it would be nice to log all node connection errors to later investigate what was the problem. But while it is possible to subscribe to 'offline' event on PoolCluster, it does not provide error details why node was put offline.

Is there any way to get connection errors info from PoolCluster other than not using "canRetry=true" and doing re-tries manually?

Emitting something like 'node-error' event on PoolCluster with node and error details would be nice. Another way can be accumulating errors in node object and passing them into 'offline' event.

Contributor guide

Tech stack
javascriptnodejs
Domain
backenddatabase
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
basic understanding of MySQL pool clusterNode.js event system
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40
Research direction
Investigate the PoolCluster class in lib/pool cluster.js, specifically the handling of node errors and the 'offline' event. Consider adding a new 'node error' event that emits error details when a node connection fails, or alternatively modifying the 'offline' event to include accumulated errors. Ensure backward compatibility.