Alternative to "master" and "slave" in entity relationship?

Beyond 'Master/Slave': Inclusive Terminology in Entity Relationships

Explore modern, inclusive alternatives to 'master' and 'slave' in database and system architecture, focusing on clear, respectful, and technically accurate terminology for entity relationships.

The terms "master" and "slave" have historically been used in computing to describe hierarchical relationships between components, particularly in database replication, distributed systems, and hardware configurations. However, these terms carry problematic connotations rooted in human history and can be alienating or offensive. As the tech industry strives for greater inclusivity, there's a growing consensus to adopt more neutral, descriptive, and respectful language. This article explores why this shift is important and provides practical alternatives for describing various entity relationships in your technical documentation and discussions.

Why Change Terminology?

The primary motivation for moving away from "master/slave" terminology is inclusivity. Language shapes perception, and using terms associated with oppressive historical practices can create an unwelcoming environment for many. Beyond the ethical considerations, adopting clearer, more descriptive terms can also improve technical communication by focusing on the functional roles rather than loaded metaphors. For instance, describing a database as a 'primary' and its replicas as 'secondaries' immediately conveys their roles in data consistency and availability without relying on potentially offensive analogies.

Common Scenarios and Alternatives

Different contexts require different alternative terms. Here's a breakdown of common scenarios where 'master/slave' is used and suitable replacements:

erDiagram
    PRIMARY ||--o{ REPLICA : replicates
    LEADER ||--o{ FOLLOWER : leads
    CONTROLLER ||--o{ AGENT : manages
    SOURCE ||--o{ TARGET : sends_data_to
    PUBLISHER ||--o{ SUBSCRIBER : publishes_to

Entity Relationship Diagram showing inclusive terminology alternatives

Database Replication and High Availability

In database systems, one instance often handles writes while others maintain copies of the data. This is a classic 'master/slave' scenario. Here are better options:

• Primary/Replica: This is perhaps the most common and widely accepted alternative. The 'primary' handles writes and is the authoritative source, while 'replicas' maintain copies and can serve read requests.
• Primary/Secondary: Similar to primary/replica, clearly indicating the main instance and its backups.
• Source/Target: Describes the direction of data flow, where the 'source' provides data to the 'target' instances.
• Leader/Follower: Often used in distributed consensus algorithms (e.g., Raft, Paxos) where a 'leader' coordinates operations among 'followers'.

-- Example: Setting up a PostgreSQL primary-replica configuration
-- On the primary server:
CREATE ROLE replication_user WITH REPLICATION LOGIN PASSWORD 'your_password';

-- On the replica server:
SELECT pg_basebackup(
    'host=primary_ip port=5432 user=replication_user password=your_password',
    'pg_data_directory',
    'stream', 'wal', 'fast', 'progress'
);

-- In recovery.conf (or postgresql.conf for newer versions):
-- primary_conninfo = 'host=primary_ip port=5432 user=replication_user password=your_password application_name=replica1'
-- restore_command = 'cp /path/to/wal_archive/%f %p'

Illustrative SQL for setting up a primary-replica database.

Distributed Systems and Control Flow

In distributed systems, one component might orchestrate tasks or manage resources for others. Alternatives include:

• Controller/Agent: A 'controller' manages or orchestrates tasks performed by 'agents'.
• Orchestrator/Worker: An 'orchestrator' assigns and coordinates work among 'worker' nodes.
• Host/Client: Common in network protocols where a 'host' provides services to 'clients'.
• Server/Client: The ubiquitous model for request-response interactions.
• Main/Auxiliary: For components that play a supporting role to a central 'main' component.

Practical Implementation and Communication

Implementing this change requires more than just updating code comments. It involves:

1. Auditing Existing Documentation: Review all internal and external documentation, codebases, and configuration files for problematic terms.
2. Updating Code and Configuration: Rename variables, functions, and configuration parameters where appropriate. This might be a larger refactoring effort for older systems.
3. Educating Teams: Ensure all team members understand the rationale behind the change and consistently use the new terminology.
4. Community Engagement: Participate in discussions within open-source projects or standards bodies to advocate for and adopt inclusive language.

While the initial effort might seem significant, the long-term benefits of fostering an inclusive environment and improving clarity in technical communication far outweigh the costs.