# Phase 4 Implementation Roadmap
## Advanced Database & Issue Pattern Checks

**Date**: February 26, 2026
**Current Status**: Ready for implementation
**Target Coverage**: 92% → 93%
**Estimated Effort**: 30-40 hours
**Total New Checks**: 22 functions

---

## PHASE 4 SCOPE

Phase 4 adds the highest-impact checks from the 40+ additional opportunities:
- **Advanced Database Tuning** (12 checks)
- **Issue Pattern Detection** (10 checks)

---

## TIER 1: QUICK WINS (Implement First - 15 hours)

These 12 checks have clear implementation paths and high impact.

### Database Quick Wins (6 checks)

#### 1. `analyze_table_engine_mismatch()` [Database]
**Impact**: HIGH | **Difficulty**: EASY | **Time**: 1.5 hours

Detects MyISAM tables on InnoDB-configured servers (inconsistency increases query time).

```bash
# Implementation approach:
# Query: SELECT DISTINCT ENGINE FROM information_schema.TABLES WHERE TABLE_SCHEMA = DATABASE()
# Look for ENGINE != 'InnoDB' when SYS_DB_TYPE is InnoDB
# Remediation: ALTER TABLE {table} ENGINE=InnoDB;
```

**Performance Impact**: 5-20% improvement if tables converted

---

#### 2. `analyze_table_statistics_age()` [Database]
**Impact**: HIGH | **Difficulty**: EASY | **Time**: 1.5 hours

Checks if table statistics are stale (causes query optimizer to make poor decisions).

```bash
# Implementation approach:
# Query: SELECT * FROM mysql.innodb_table_stats
# Check STAT_MODIFIED > CURRENT_DATE - INTERVAL 30 DAY
# Remediation: ANALYZE TABLE {table};
```

**Performance Impact**: 10-30% improvement with fresh statistics

---

#### 3. `analyze_index_cardinality()` [Database]
**Impact**: HIGH | **Difficulty**: MEDIUM | **Time**: 2 hours

Identifies indexes with poor cardinality that won't be used by optimizer.

```bash
# Implementation approach:
# Query: SELECT * FROM information_schema.STATISTICS
# Calculate cardinality ratio: SEQ_IN_INDEX / CARDINALITY
# Flag if ratio > 0.95 (poor selectivity)
```

**Performance Impact**: 15-40% improvement from index optimization

---

#### 4. `analyze_query_cache_memory_waste()` [Database]
**Impact**: MEDIUM | **Difficulty**: EASY | **Time**: 1 hour

Detects query cache fragmentation (MySQL 5.7).

```bash
# Implementation approach:
# SHOW STATUS LIKE 'Qcache%'
# Calculate waste: (Qcache_free_blocks / Qcache_total_blocks) * 100
# Alert if > 30% fragmentation
```

**Performance Impact**: Better cache efficiency

---

#### 5. `analyze_replication_lag()` [Database]
**Impact**: HIGH | **Difficulty**: MEDIUM | **Time**: 2 hours

For replicated databases, check if replica is lagging (read performance impacts).

```bash
# Implementation approach:
# SHOW SLAVE STATUS\G
# Check Seconds_Behind_Master
# Alert if > 10 seconds
```

**Performance Impact**: Critical for multi-server setups

---

#### 6. `analyze_table_size_growth()` [Database]
**Impact**: MEDIUM | **Difficulty**: MEDIUM | **Time**: 2 hours

Compares growth rate of tables to identify runaway logging tables.

```bash
# Implementation approach:
# Track table size from INFORMATION_SCHEMA
# Compare to 30 days ago (if accessible)
# Alert if growth > 1GB/month
```

**Performance Impact**: Prevent disk exhaustion

---

### Issue Pattern Quick Wins (6 checks)

#### 7. `analyze_timeout_errors()` [Error Patterns]
**Impact**: HIGH | **Difficulty**: EASY | **Time**: 1 hour

Counts timeout errors in error logs (indicates slowness issues).

```bash
# Implementation approach:
# Parse error_log for "timeout" / "timed out"
# Count in last 24 hours
# Alert if count > 10
```

**Performance Impact**: Identifies actual customer impact

---

#### 8. `analyze_memory_exhaustion_attempts()` [Error Patterns]
**Impact**: HIGH | **Difficulty**: EASY | **Time**: 1 hour

Detects when PHP processes hit memory limits.

```bash
# Implementation approach:
# Parse error_log for "Allowed memory size"
# Count in last 24 hours
# Remediation: Increase PHP memory_limit
```

**Performance Impact**: Prevents request failures

---

#### 9. `analyze_disk_inode_usage()` [System Resources]
**Impact**: MEDIUM | **Difficulty**: EASY | **Time**: 1 hour

Checks inode usage (filesystem performance degrades at high usage).

```bash
# Implementation approach:
# df -i
# Alert if usage > 80%
# Remediation: Find and delete old logs, tmp files
```

**Performance Impact**: Filesystem performance impact

---

#### 10. `analyze_zombie_processes()` [System Resources]
**Impact**: MEDIUM | **Difficulty**: EASY | **Time**: 1 hour

Detects zombie PHP/MySQL processes (resource leak).

```bash
# Implementation approach:
# ps aux | grep -c "Z "
# Alert if count > 5
# Remediation: Restart PHP-FPM / MySQL
```

**Performance Impact**: Frees up process slots

---

#### 11. `analyze_swap_usage()` [System Resources]
**Impact**: HIGH | **Difficulty**: EASY | **Time**: 1 hour

Detects if system is using swap (massive performance killer).

```bash
# Implementation approach:
# free | grep Swap
# If Swap_used > 0, alert CRITICAL
# Remediation: Add more RAM or reduce memory usage
```

**Performance Impact**: 50-100x slower if using swap

---

#### 12. `analyze_load_average_trend()` [System Resources]
**Impact**: MEDIUM | **Difficulty**: MEDIUM | **Time**: 1.5 hours

Compares load average across 1/5/15 minute windows to detect trends.

```bash
# Implementation approach:
# uptime command parsing
# Calculate: load_5min / load_1min ratio
# Alert if increasing trend (> 1.2x)
```

**Performance Impact**: Early warning system

---

## TIER 2: MEDIUM PRIORITY (Implement Second - 15 hours)

Additional 10 checks with slightly more complex implementation.

### Advanced Database (4 additional checks)

#### 13. `analyze_foreign_key_validation()` [Database]
**Impact**: MEDIUM | **Difficulty**: MEDIUM | **Time**: 2 hours

Checks if foreign key constraints are impacting insert/update performance.

#### 14. `analyze_trigger_count()` [Database]
**Impact**: MEDIUM | **Difficulty**: MEDIUM | **Time**: 2 hours

Detects excessive database triggers that slow down writes.

#### 15. `analyze_procedure_optimization()` [Database]
**Impact**: LOW | **Difficulty**: HARD | **Time**: 3 hours

Analyzes stored procedures for performance issues.

#### 16. `analyze_column_charset_consistency()` [Database]
**Impact**: LOW | **Difficulty**: MEDIUM | **Time**: 2 hours

Checks for charset inconsistencies causing query slowdowns.

---

### Issue Patterns (6 additional checks)

#### 17. `analyze_gateway_timeout_patterns()` [Error Patterns]
**Impact**: HIGH | **Difficulty**: EASY | **Time**: 1 hour

Detects 504 Gateway Timeout errors in access log.

#### 18. `analyze_database_connection_rejections()` [Error Patterns]
**Impact**: HIGH | **Difficulty**: EASY | **Time**: 1 hour

Counts "too many connections" errors in MySQL error log.

#### 19. `analyze_plugin_fatal_errors()` [Error Patterns]
**Impact**: MEDIUM | **Difficulty**: MEDIUM | **Time**: 2 hours

Detects PHP fatal errors from specific plugins.

#### 20. `analyze_dns_resolution_failures()` [Network]
**Impact**: MEDIUM | **Difficulty**: MEDIUM | **Time**: 2 hours

Checks for DNS timeout errors in logs.

#### 21. `analyze_file_descriptor_exhaustion()` [System Resources]
**Impact**: HIGH | **Difficulty**: MEDIUM | **Time**: 2 hours

Detects when file descriptors are exhausted.

#### 22. `analyze_concurrent_request_backlog()` [System Resources]
**Impact**: MEDIUM | **Difficulty**: MEDIUM | **Time**: 2 hours

Analyzes request queue depth from Apache/Nginx logs.

---

## IMPLEMENTATION ORDER

**Day 1-2**: Implement Tier 1 Quick Wins (12 checks)
- 6 Database checks (1.5-2 hours each)
- 6 Issue Pattern checks (1-1.5 hours each)

**Day 3-4**: Implement Tier 2 Medium Priority (10 checks)
- 4 Advanced database checks (2-3 hours each)
- 6 Issue pattern checks (1-2 hours each)

**Day 5**: Integration & Testing (8 hours)
- Add all 22 functions to extended-analysis-functions.sh
- Add function calls to run_diagnostics()
- Update remediation engine with new check patterns
- Syntax validation & testing
- Documentation update

---

## CODE STRUCTURE FOR TIER 1 QUICK WINS

All new functions follow this pattern:

```bash
analyze_table_engine_mismatch() {
    local check_name="table_engine_mismatch"
    local finding_value=""
    local finding_severity="INFO"

    # Execute check
    local mismatched=$(mysql -e "SELECT DISTINCT ENGINE FROM information_schema.TABLES" 2>/dev/null | grep -vc "InnoDB")

    if [ "$mismatched" -gt 0 ]; then
        finding_value="Found $mismatched tables with non-InnoDB engine"
        finding_severity="WARNING"
        print_warning "Database: $finding_value"
        echo "$check_name|$finding_value|$finding_severity" >> "$TEMP_DIR/findings.tmp"
    fi
}

# Export function
export -f analyze_table_engine_mismatch
```

---

## INTEGRATION POINTS

### 1. Add to extended-analysis-functions.sh
- All 22 new functions after existing 32 functions
- Maintain same naming convention
- Add proper error handling

### 2. Add to website-slowness-diagnostics.sh
In the `run_diagnostics()` function, add new calls:

```bash
# Phase 4: Advanced Database Analysis (12 checks)
print_section "ADVANCED DATABASE ANALYSIS"
analyze_table_engine_mismatch
analyze_table_statistics_age
analyze_index_cardinality
analyze_query_cache_memory_waste
analyze_replication_lag
analyze_table_size_growth
analyze_foreign_key_validation
analyze_trigger_count
analyze_procedure_optimization
analyze_column_charset_consistency

# Phase 4: Issue Pattern Detection (10 checks)
print_section "ERROR PATTERN & SYSTEM RESOURCE ANALYSIS"
analyze_timeout_errors
analyze_memory_exhaustion_attempts
analyze_disk_inode_usage
analyze_zombie_processes
analyze_swap_usage
analyze_load_average_trend
analyze_gateway_timeout_patterns
analyze_database_connection_rejections
analyze_plugin_fatal_errors
analyze_dns_resolution_failures
analyze_file_descriptor_exhaustion
analyze_concurrent_request_backlog
```

### 3. Remediation Engine Updates
Add new case statements to `generate_remediation()` for:
- table_engine_mismatch
- swap_usage (CRITICAL)
- zombie_processes
- timeout_errors
- memory_exhaustion_attempts
- file_descriptor_exhaustion

Each with specific remediation commands.

---

## TESTING CHECKLIST

- [ ] All 22 functions pass syntax validation
- [ ] Database functions work with MySQL 5.7, 8.0, MariaDB 10.5
- [ ] Error log parsing works with Apache, Nginx, PHP-FPM
- [ ] System resource checks work on CentOS/Ubuntu/Debian
- [ ] All remediation recommendations are accurate
- [ ] No false positives on clean systems
- [ ] Performance impact < 5 seconds for all checks
- [ ] Proper error handling when databases/logs unavailable

---

## DOCUMENTATION UPDATES

After implementation:
1. Update REMEDIATION_MAPPING.md to include 22 new checks
2. Update REMEDIATION_MASTER_INDEX.md with new coverage: 86+ checks (93%)
3. Update IMPLEMENTATION_COMPLETE.md with Phase 4 status
4. Create PHASE_4_COMPLETION.md with detailed results

---

## COMMIT STRATEGY

```bash
git add modules/website/lib/extended-analysis-functions.sh
git add modules/website/website-slowness-diagnostics.sh
git add modules/website/lib/remediation-engine.sh
git add docs/PHASE_4_ROADMAP.md

git commit -m "Phase 4: Add 22 advanced database and issue pattern checks

- Added 12 database analysis functions
- Added 10 error pattern detection functions
- Coverage: 92% -> 93% (86+ total checks)
- All functions follow existing patterns
- Comprehensive remediation recommendations
"
```

---

## NEXT: Phase 5 & 6

After Phase 4 completion:
- **Phase 5** (18 checks): Content & Network analysis (95% coverage) - 30 hours
- **Phase 6** (22 checks): Framework-specific & System (97%+ coverage) - 40 hours

Full implementation: ~110 hours additional effort from Phase 4 baseline

---

**Status**: Ready to implement
**Recommendation**: Start with Tier 1 Quick Wins (12 checks) for quick 1-2 day implementation
