Qtopology-mysql NPM

qtopology-mysql

This package contains coordination-storage plugin for QTopology that uses MySQL database to store and manipulate coordination data.

npm install qtopology-mysql

The database doesn't need to be prepared in advance. All the objects will be created automatically, using the scripts in the db directory:

init.sql - create initial database state that will be used to upgrade schema to latest version.
reset.sql - resets database schema to the initial state. Removes all data, tables and stored procedures.
clear.sql - just erases all data, but leaves schema in tact. Should be used on the latest schema.
vX.sql - version upgrades.

Each time the coordinator is instantiated, it first peforms database initialization by executing these steps:

run init.js
fetch version from database
detect version-upgrade files that need to be run
for each upgrade file
    run file
    update version

If database schema is already at the latest version, then nothing happens.

Table	Description
qtopology_settings	Simple settings, also contains version information
qtopology_worker	List of workers, their statuses and latest pings
qtopology_topology	List of topologies, their statuses and latest pings
qtopology_message	Message queue for workers
qtopology_worker_history	List of important changes inside `qtopology_worker` table
qtopology_topology_hostory	List of important changes inside `qtopology_topology` table

Table	Description
qtopology_sp_add_topology_history	Enters new historical record for topology
qtopology_sp_add_worker_history	Enters new historical record for worker
qtopology_sp_announce_leader_candidacy	Sets status for given worker that it is a candidate for leadership
qtopology_sp_check_leader_candidacy	Checks if leadership candidacy succeeded for given worker
qtopology_sp_disable_defunct_leaders	Disables leaders that have been inactive too long or are marked as dead
qtopology_sp_disable_defunct_workers	Disables workers that have been inactive too long or are marked as dead
qtopology_sp_leader_ping	Updates last ping for given leader
qtopology_sp_worker_ping	Updates last ping for given worker, doesn't change status
qtopology_sp_messages_for_worker	Retrieves messages for single worker
qtopology_sp_refresh_statuses	Refreshes all statuses by calling other stored procedures that update inactive workers etc.
qtopology_sp_register_topology	Registers new topology. If topology exists, it is overwritten.
qtopology_sp_register_worker	Registers new worker. If worker exists, it is overwritten.
qtopology_sp_unassign_waiting_topologies	Sets topologies that have been assigned a while ago but are not running as unassigned.
qtopology_sp_worker_statuses	Counts how many workers are in certain leadership status.