Multi-Tenancy & Sharding Documentation

This directory contains documentation for PropertyWebBuilder's multi-tenancy architecture and database sharding system.

Core Documentation

Architecture & Reference

• MULTI_TENANCY_DATABASE_REFERENCE.md - Complete database architecture reference
• MULTI_TENANCY_EXPLORATION_SUMMARY.md - System exploration summary
• MULTI_TENANCY_QUICK_START.md - Quick start guide

Sharding

• PREMIUM_ENTERPRISE_SHARDING_PLAN.md - Enterprise sharding plan
• DEMO_SHARD_GUIDE.md - Demo shard setup guide

Shard Admin Implementation (NEW - 2026-01-08)

• SHARD_ADMIN_IMPLEMENTATION_PLAN.md - Complete implementation plan (48KB)
• SHARD_ADMIN_IMPLEMENTATION_UPDATES.md - Codebase-aligned updates (28KB)

Shard Admin Implementation

Overview

The Shard Admin project adds a complete UI for managing database shards in the Tenant Admin interface.

Status: Planning Complete ✅
Implementation: Not Started
Estimated Effort: 2-3 weeks

What Will Be Built

Phase 1 (Week 1): Foundation

• Shard dashboard showing all configured shards
• Website shard assignment UI
• Audit logging for all changes
• Health monitoring basics

Phase 2 (Week 2): Advanced Features

• Detailed health monitoring with PgHero
• Bulk shard assignment
• Statistics & capacity tracking
• Turbo/Stimulus dynamic UI

Phase 3 (Week 3): Migration Tools

• Background migration jobs
• Progress tracking
• Verification & rollback
• Email notifications

Key Features

✅ Read from Actual Codebase

• Uses Pwb::ShardRegistry (not invented API)
• Uses Pwb::TenantShardMigrator (actual class name)
• Integrates with existing PgHero installation

✅ Modern Rails 8

• Turbo Streams for instant updates
• Stimulus controllers for interactivity
• Solid Queue for background jobs
• Feature flags for gradual rollout

✅ Production Ready

• Comprehensive validation
• Risk mitigation strategies
• Audit trail for all operations
• CLI tools (Rake tasks)
• API endpoints for monitoring

Quick Reference

Access: /tenant_admin/shards (requires TENANT_ADMIN_EMAILS)

CLI Commands:

# Status check
bin/rails pwb:shards:status

# Assign website to shard
bin/rails pwb:shards:assign[42,shard_1]

# Health check
bin/rails pwb:shards:health

Feature Flags (Progressive Rollout):

SHARD_ADMIN_ENABLED=true          # Enable dashboard
SHARD_ASSIGNMENT_ENABLED=true     # Enable assignment
SHARD_MIGRATIONS_ENABLED=true     # Enable data migration

Getting Started

1. Read the Plan:

   • Start with SHARD_ADMIN_IMPLEMENTATION_PLAN.md
   • Review SHARD_ADMIN_IMPLEMENTATION_UPDATES.md for codebase-specific details

2. Understand Dependencies:

   • Existing: Pwb::ShardRegistry, Pwb::TenantShardMigrator, PgHero
   • New: Pwb::ShardService, Pwb::ShardHealthCheck, Pwb::ShardAuditLog

3. Phase 1 Implementation:

   • Create database migration for pwb_shard_audit_logs
   • Create routes in tenant_admin namespace
   • Create ShardsController
   • Create views with Tailwind CSS
   • Add shard column to websites index

Risk Assessment

Risk	Mitigation
Unconfigured shard assignment	Validate with ShardRegistry.configured?
Data loss during migration	Transactions, verification, source preservation
Concurrent operations	Database locks, single-queue processing
Permission escalation	Strict TENANT_ADMIN_EMAILS validation

Success Criteria

• All tests passing (unit, controller, integration)
• Can view all configured shards
• Can assign websites to shards
• Audit logs created for all changes
• Health monitoring working
• Documentation complete

Additional Resources

• Database configuration: config/database.yml
• Shard registry: app/lib/pwb/shard_registry.rb
• Migrator service: app/services/pwb/tenant_shard_migrator.rb
• Application record: app/models/pwb_tenant/application_record.rb

Questions?

See the implementation plan for detailed answers on:

• Architecture decisions
• Security model
• Testing strategy
• Deployment procedures
• Troubleshooting guide