---
task_id: sprint_2_story_1_task_1
story: sprint_2_story_1
status: not_started
estimated_hours: 4
created_date: 2025-11-05
assignee: Backend Team
---

# Task 1: Design AuditLog Database Schema and Create Migration

**Story**: Story 1 - Audit Log Foundation (Phase 1)
**Estimated**: 4 hours

## Description

Design and implement the AuditLog database table schema with proper columns, data types, and indexes to support efficient audit querying and multi-tenant isolation.

## Acceptance Criteria

- [ ] Database migration created with AuditLog table
- [ ] All required columns defined with correct data types
- [ ] Composite indexes created for query optimization
- [ ] Multi-tenant isolation enforced (TenantId column)
- [ ] Migration applied successfully

## Implementation Details

**Table Schema**:
```sql
CREATE TABLE AuditLogs (
    Id UUID PRIMARY KEY,
    TenantId UUID NOT NULL,
    EntityType VARCHAR(100) NOT NULL,
    EntityId UUID NOT NULL,
    Action VARCHAR(20) NOT NULL, -- 'Create', 'Update', 'Delete'
    UserId UUID NULL,
    Timestamp TIMESTAMPTZ NOT NULL DEFAULT NOW(),
    OldValues JSONB NULL,
    NewValues JSONB NULL,

    CONSTRAINT FK_AuditLogs_Tenants FOREIGN KEY (TenantId) REFERENCES Tenants(Id) ON DELETE CASCADE
);

-- Indexes for query performance
CREATE INDEX IX_AuditLogs_TenantId_EntityType_EntityId ON AuditLogs(TenantId, EntityType, EntityId);
CREATE INDEX IX_AuditLogs_Timestamp ON AuditLogs(Timestamp DESC);
CREATE INDEX IX_AuditLogs_UserId ON AuditLogs(UserId);
```

**Files to Modify**:
- Create: `colaflow-api/src/ColaFlow.Infrastructure/Data/Migrations/{timestamp}_AddAuditLogTable.cs`

## Technical Notes

- Use PostgreSQL JSONB for `OldValues`/`NewValues` (flexible schema, indexed queries)
- Composite index on `(TenantId, EntityType, EntityId)` for efficient entity history queries
- `Timestamp` index with DESC order for recent logs queries
- Consider table partitioning for future scalability (Phase 4)

## Testing

- Verify migration runs without errors
- Check indexes are created
- Verify foreign key constraints work

---

**Created**: 2025-11-05 by Backend Agent