eventsourcing/es4j

Problem: PostgreSQL database provisioning contention

Open

#208 opened on Jan 27, 2017

View on GitHub
 (0 comments) (0 reactions) (0 assignees)Java (406 stars) (27 forks)batch import
bughelp wanted

Description

PostgreSQL-backed journal & indices will create necessary tables and types without consideration for others — meaning there might be a conflict and two nodes might attempt to do the same thing at the same time.

Proposed solution: ensure these storages are locking these initialization routines. PostgreSQL advisory locks can be used to easily accomplish this.

Contributor guide

Tech stack
javapostgresql
Domain
backenddatabase
Issue type
bug
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.
1-3 hours
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
Java programmingPostgreSQL basicsConcurrency concepts
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
50
Research direction
The issue describes a race condition when multiple nodes initialize PostgreSQL tables simultaneously. The proposed solution is to use PostgreSQL advisory locks. To implement this, look at the code that creates tables and types (likely in the Journal and Index classes) and wrap those initialization routines with advisory lock acquisition and release. The locks should be taken with a unique identifier, e.g., the table name or a constant. Ensure proper error handling and lock release. No additional context from maintainers is available as the issue has no comments.