# Index Strategy & Performance

## Overview

Changemaker Lite V2 uses strategic indexing across 33 models to optimize query performance. This document catalogs all indexes, explains their purpose, and provides query optimization guidance.

**Total Indexes:** 60+ (Prisma: 50+, Drizzle: 10+)

**Index Types:**
- **Unique indexes** — Enforce uniqueness constraints (email, slug, token, etc.)
- **Foreign key indexes** — Optimize JOIN operations (userId, campaignId, locationId, etc.)
- **Composite indexes** — Multi-column indexes for complex queries
- **Spatial indexes** — Latitude/longitude for geographic queries

---

## Index Catalog

### Auth & Users

#### User
- **Unique:** `email` — Login lookups (`WHERE email = ?`)

#### RefreshToken
- **Unique:** `token` — Refresh endpoint lookups (`WHERE token = ?`)
- **Foreign Key:** `userId` — User deletion cascades

---

### Influence

#### Campaign
- **Unique:** `slug` — Public campaign page lookups (`WHERE slug = ?`)

#### Representative
- **Non-unique:** `postalCode` — Postal code lookups (`WHERE postalCode = ?`)

#### CampaignEmail
- **Foreign Key:** `campaignId` — Campaign email stats (`JOIN campaign_emails ON campaign_id = ?`)
- **Non-unique:** `campaignSlug` — Slug-based queries

#### RepresentativeResponse
- **Foreign Key:** `campaignId` — Campaign response wall (`JOIN representative_responses ON campaign_id = ?`)
- **Non-unique:** `campaignSlug` — Slug-based queries

#### ResponseUpvote
- **Unique:** `[responseId, userId]` — Prevent duplicate upvotes from logged-in users
- **Unique:** `[responseId, upvotedIp]` — Prevent duplicate upvotes from same IP

#### CustomRecipient
- **Foreign Key:** `campaignId` — Campaign custom recipients (`JOIN custom_recipients ON campaign_id = ?`)

#### PostalCodeCache
- **Unique:** `postalCode` — Postal code cache lookups (`WHERE postal_code = ?`)

#### Call
- **Foreign Key:** `campaignId` — Campaign call tracking (`JOIN calls ON campaign_id = ?`)

---

### Map — Locations

#### Location
- **Unique:** `locGuid` — NAR location GUID lookups
- **Composite:** `[latitude, longitude]` — **Spatial queries** (nearby locations, bounding box searches)
- **Non-unique:** `postalCode` — Postal code filtering

**Query Optimization:**
```sql
-- Uses composite index for bounding box queries
SELECT * FROM locations
WHERE latitude BETWEEN ? AND ?
  AND longitude BETWEEN ? AND ?;
```

#### Address
- **Unique:** `addrGuid` — NAR address GUID lookups
- **Foreign Key:** `locationId` — Location addresses (`JOIN addresses ON location_id = ?`)
- **Composite:** `[locationId, unitNumber]` — **Unit lookups within building**

**Query Optimization:**
```sql
-- Uses composite index for unit-specific queries
SELECT * FROM addresses
WHERE location_id = ? AND unit_number = ?;
```

#### LocationHistory
- **Foreign Key:** `locationId` — Location history (`JOIN location_history ON location_id = ?`)
- **Foreign Key:** `userId` — User edit history (`JOIN location_history ON user_id = ?`)
- **Non-unique:** `createdAt` — **Temporal queries** (recent edits, audit trails)

---

### Map — Shifts & Cuts

#### Shift
- **Foreign Key:** `cutId` — Cut shifts (`JOIN shifts ON cut_id = ?`)

#### ShiftSignup
- **Unique:** `[shiftId, userEmail]` — **Prevent duplicate shift signups**
- **Foreign Key:** `shiftId` — Shift signups (`JOIN shift_signups ON shift_id = ?`)

---

### Canvassing

#### CanvassSession
- **Foreign Key:** `userId` — User canvass sessions (`JOIN canvass_sessions ON user_id = ?`)
- **Foreign Key:** `cutId` — Cut canvass sessions (`JOIN canvass_sessions ON cut_id = ?`)
- **Foreign Key:** `shiftId` — Shift canvass sessions (`JOIN canvass_sessions ON shift_id = ?`)

#### CanvassVisit
- **Foreign Key:** `addressId` — Address visit history (`JOIN canvass_visits ON address_id = ?`)
- **Foreign Key:** `userId` — User visit history (`JOIN canvass_visits ON user_id = ?`)
- **Foreign Key:** `shiftId` — Shift visits (`JOIN canvass_visits ON shift_id = ?`)
- **Foreign Key:** `sessionId` — Session visits (`JOIN canvass_visits ON session_id = ?`)
- **Non-unique:** `visitedAt` — **Temporal queries** (recent visits, activity feeds)

#### TrackingSession
- **Unique:** `canvassSessionId` — **One-to-one relationship** with CanvassSession
- **Foreign Key:** `userId` — User GPS sessions (`JOIN tracking_sessions ON user_id = ?`)
- **Non-unique:** `isActive` — Active session filtering (`WHERE is_active = true`)
- **Composite:** `[isActive, lastRecordedAt]` — **Session cleanup queries** (abandoned sessions)

**Query Optimization:**
```sql
-- Uses composite index for abandoned session cleanup
SELECT * FROM tracking_sessions
WHERE is_active = true
  AND last_recorded_at < NOW() - INTERVAL '12 hours';
```

#### TrackPoint
- **Composite:** `[trackingSessionId, recordedAt]` — **Temporal GPS queries** (session breadcrumb trail)
- **Non-unique:** `recordedAt` — Cross-session temporal queries

---

### Email Templates

#### EmailTemplate
- **Unique:** `key` — Template key lookups (`WHERE key = 'campaign-email'`)
- **Non-unique:** `category` — Category filtering (`WHERE category = 'INFLUENCE'`)
- **Non-unique:** `isActive` — Active template filtering (`WHERE is_active = true`)

#### EmailTemplateVariable
- **Unique:** `[templateId, key]` — **Unique variable keys per template**
- **Foreign Key:** `templateId` — Template variables (`JOIN email_template_variables ON template_id = ?`)

#### EmailTemplateVersion
- **Unique:** `[templateId, versionNumber]` — **Sequential version numbers per template**
- **Composite:** `[templateId, createdAt(sort: Desc)]` — **Recent version history**

**Query Optimization:**
```sql
-- Uses composite index for recent version queries
SELECT * FROM email_template_versions
WHERE template_id = ?
ORDER BY created_at DESC
LIMIT 10;
```

#### EmailTemplateTestLog
- **Composite:** `[templateId, sentAt(sort: Desc)]` — **Recent test logs**

---

### Landing Pages

#### LandingPage
- **Unique:** `slug` — Public page lookups (`WHERE slug = 'about'`)

---

### Media (Drizzle ORM)

#### videos
- **Unique:** `path` — File path lookups (`WHERE path = '/media/local/videos/file.mp4'`)
- **Non-unique:** `orientation` — Orientation filtering (`WHERE orientation = 'landscape'`)
- **Non-unique:** `producer` — Producer filtering (`WHERE producer = 'Studio A'`)
- **Non-unique:** `isValid` — Valid video filtering (`WHERE is_valid = true`)
- **Non-unique:** `directoryType` — Directory type filtering (`WHERE directory_type = 'studios'`)
- **Composite:** `[durationSeconds, fileSize, width, height]` — **Fingerprint matching** (duplicate detection)
- **Composite:** `[directoryType, isValid, orientation]` — **Common filtering pattern**

**Query Optimization:**
```sql
-- Uses composite index for common video library queries
SELECT * FROM videos
WHERE directory_type = 'studios'
  AND is_valid = true
  AND orientation = 'landscape';
```

#### jobs
- **Composite:** `[status, priority, createdAt]` — **Job queue processing**
- **Composite:** `[resourceCategory, status]` — **Resource-based filtering**
- **Non-unique:** `pipelineId` — Pipeline job filtering

**Query Optimization:**
```sql
-- Uses composite index for job queue queries
SELECT * FROM jobs
WHERE status = 'pending'
ORDER BY priority ASC, created_at ASC
LIMIT 10;
```

---

## Query Optimization Patterns

### 1. Use Indexes for WHERE Clauses
```typescript
// ✅ Uses email unique index
await prisma.user.findUnique({ where: { email: 'user@example.com' } });

// ❌ Full table scan (no index on name)
await prisma.user.findMany({ where: { name: 'John' } });
```

### 2. Use Composite Indexes for Multi-Column Filters
```typescript
// ✅ Uses [latitude, longitude] composite index
await prisma.location.findMany({
  where: {
    latitude: { gte: 53.5, lte: 53.6 },
    longitude: { gte: -113.5, lte: -113.4 },
  },
});

// ❌ Less efficient (only uses latitude index)
await prisma.location.findMany({
  where: {
    latitude: { gte: 53.5, lte: 53.6 },
    // longitude filter applied after index scan
  },
});
```

### 3. Use Foreign Key Indexes for JOINs
```typescript
// ✅ Uses campaignId foreign key index
await prisma.campaign.findUnique({
  where: { id: campaignId },
  include: { emails: true }, // JOIN uses index
});

// ❌ N+1 query (loads emails one-by-one)
const campaign = await prisma.campaign.findUnique({ where: { id: campaignId } });
const emails = await prisma.campaignEmail.findMany({ where: { campaignId: campaign.id } });
```

### 4. Use Unique Indexes for Deduplication
```typescript
// ✅ Uses [responseId, userId] unique index
await prisma.responseUpvote.create({
  data: { responseId, userId, upvotedIp },
});
// Throws error if user already upvoted (database-level check)

// ❌ Application-level check (race condition)
const existing = await prisma.responseUpvote.findFirst({
  where: { responseId, userId },
});
if (existing) throw new Error('Already upvoted');
await prisma.responseUpvote.create({ data: { responseId, userId } });
```

### 5. Use Temporal Indexes for Date Filtering
```typescript
// ✅ Uses createdAt index
await prisma.locationHistory.findMany({
  where: {
    createdAt: { gte: new Date('2025-01-01') },
  },
  orderBy: { createdAt: 'desc' },
  take: 100,
});

// ❌ Full table scan (no index on field)
await prisma.locationHistory.findMany({
  where: {
    oldValue: { contains: 'Calgary' }, // No index
  },
});
```

---

## Index Selectivity

**Selectivity** = Percentage of unique values in indexed column. Higher selectivity = better index performance.

### High Selectivity (Good)
- **email** (User) — 100% unique (1 user per email)
- **token** (RefreshToken) — 100% unique (1 token per record)
- **slug** (Campaign, LandingPage) — 100% unique (1 record per slug)
- **[responseId, userId]** (ResponseUpvote) — High uniqueness (1 upvote per user per response)

### Medium Selectivity (Okay)
- **postalCode** (Location) — ~50% unique (multiple locations per postal code)
- **campaignId** (CampaignEmail) — ~10% unique (100s of emails per campaign)
- **directoryType** (videos) — ~11% unique (9 directory types)

### Low Selectivity (Poor for filtering, good for covering index)
- **isActive** (TrackingSession) — ~50% unique (active vs inactive)
- **status** (Campaign) — ~25% unique (4 statuses: DRAFT, ACTIVE, PAUSED, ARCHIVED)
- **role** (User) — ~20% unique (5 roles)

**Optimization:**
- Use low-selectivity indexes as **first column in composite index** only
- Example: `[isActive, lastRecordedAt]` uses `isActive` to narrow search, then `lastRecordedAt` for ordering

---

## Index Maintenance

### Prisma Indexes (Automatic)
Prisma migrations automatically create indexes defined in `schema.prisma`:
```prisma
model Location {
  latitude  Decimal
  longitude Decimal

  @@index([latitude, longitude])  // Composite index
}
```

### Drizzle Indexes (Manual in Schema)
Drizzle indexes defined in `schema.ts`:
```typescript
export const videos = pgTable('videos', {
  directoryType: text('directory_type'),
  isValid: boolean('is_valid'),
  orientation: text('orientation'),
}, (table) => ({
  directoryValidOrientationIdx: index('idx_videos_directory_valid_orientation')
    .on(table.directoryType, table.isValid, table.orientation),
}));
```

### Index Size Monitoring
```sql
-- Check index sizes
SELECT
  tablename,
  indexname,
  pg_size_pretty(pg_relation_size(indexrelid)) AS index_size
FROM pg_stat_user_indexes
WHERE schemaname = 'public'
ORDER BY pg_relation_size(indexrelid) DESC;
```

### Unused Index Detection
```sql
-- Find indexes with zero scans (unused)
SELECT
  schemaname,
  tablename,
  indexname,
  idx_scan,
  pg_size_pretty(pg_relation_size(indexrelid)) AS index_size
FROM pg_stat_user_indexes
WHERE schemaname = 'public'
  AND idx_scan = 0
  AND indexrelid NOT IN (
    SELECT conindid FROM pg_constraint WHERE contype IN ('p', 'u')
  )
ORDER BY pg_relation_size(indexrelid) DESC;
```

---

## Performance Considerations

### Index Trade-offs
- **Pros:** Faster SELECT queries, enforces uniqueness, prevents N+1
- **Cons:** Slower INSERT/UPDATE/DELETE (index must be updated), increased storage

**Rule of Thumb:**
- Index all foreign keys (JOIN performance)
- Index all unique constraints (data integrity)
- Index columns used in WHERE clauses frequently
- Avoid indexing low-selectivity columns alone
- Avoid indexing large text fields (use full-text search instead)

### Query Planning
Use `EXPLAIN ANALYZE` to verify index usage:
```sql
EXPLAIN ANALYZE
SELECT * FROM locations
WHERE latitude BETWEEN 53.5 AND 53.6
  AND longitude BETWEEN -113.5 AND -113.4;

-- Output should show "Index Scan using locations_latitude_longitude_idx"
```

### Index Bloat
Over time, indexes can become bloated (unused space). Monitor with:
```sql
SELECT
  schemaname,
  tablename,
  indexname,
  pg_size_pretty(pg_relation_size(indexrelid)) AS index_size,
  idx_scan,
  idx_tup_read,
  idx_tup_fetch
FROM pg_stat_user_indexes
WHERE schemaname = 'public'
ORDER BY pg_relation_size(indexrelid) DESC;
```

**Fix bloat:** `REINDEX INDEX index_name;` (requires table lock)

---

## Common Performance Issues

### Issue: Slow campaign email stats query
**Query:**
```sql
SELECT COUNT(*) FROM campaign_emails WHERE campaign_id = ?;
```

**Solution:** Already optimized (uses `campaignId` foreign key index)

### Issue: Slow location bounding box queries
**Query:**
```sql
SELECT * FROM locations WHERE latitude > ? AND latitude < ? AND longitude > ? AND longitude < ?;
```

**Solution:** Already optimized (uses `[latitude, longitude]` composite index)

### Issue: Slow active session cleanup
**Query:**
```sql
SELECT * FROM tracking_sessions WHERE is_active = true AND last_recorded_at < ?;
```

**Solution:** Already optimized (uses `[isActive, lastRecordedAt]` composite index)

### Issue: Slow template version history
**Query:**
```sql
SELECT * FROM email_template_versions WHERE template_id = ? ORDER BY created_at DESC LIMIT 10;
```

**Solution:** Already optimized (uses `[templateId, createdAt(sort: Desc)]` composite index)

---

## Related Documentation

- [Database Overview](./index.md) — Complete ER diagram
- [Schema Reference](./schema.md) — All model fields
- [Migration Workflow](./migrations.md) — Creating indexes in migrations
- [Common Queries](./models/auth.md#common-queries) — Query examples with index usage
- [PostgreSQL Index Documentation](https://www.postgresql.org/docs/16/indexes.html)