Database Selection Guide: PostgreSQL vs MySQL vs MariaDB vs SQLite vs CockroachDB

Configuration Requirements for Production

PostgreSQL Production Settings

• Critical Config: max_connections = 100 (pathetically low default)
• Memory Management: Start with shared_buffers = 256MB, increase gradually
• Vacuum Settings: Requires manual tuning of autovacuum_work_mem and maintenance_work_mem
• Connection Pooling: PgBouncer is mandatory - PostgreSQL uses 1 process per connection
• Version-Specific Issue: PostgreSQL 17.0 has parallel query deadlock bug - add max_parallel_workers_per_gather = 0

MySQL Production Settings

• Critical Config: sql_mode = 'STRICT_TRANS_TABLES,NO_ZERO_DATE,NO_ZERO_IN_DATE,ERROR_FOR_DIVISION_BY_ZERO'
• Connection Handling: Default max_connections = 151, thread-based (more efficient than PostgreSQL)
• Binary Log Management: MySQL 8.4.0 disk fill issue - set binlog_expire_logs_seconds = 604800 (7 days)
• Memory Usage: Reasonable defaults, minimal tuning required

MariaDB Production Settings

• Compatibility Warning: "MySQL compatibility" breaks in subtle ways during upgrades
• Charset Issues: UTF-8 handling changed between versions, causes data corruption
• Galera Cluster: Split-brain scenarios require manual intervention with galera_new_cluster

SQLite Production Settings

• Concurrency: Enable PRAGMA journal_mode=WAL for better concurrent writes
• Maintenance: Run VACUUM manually to reclaim space after deletions
• Auto-cleanup: Set PRAGMA auto_vacuum = INCREMENTAL with periodic PRAGMA incremental_vacuum

CockroachDB Production Settings

• Clock Sync: Requires NTP synchronization within 500ms across all nodes
• Enterprise Features: Production features require expensive enterprise licensing
• Complex Config: Distributed cluster configuration demands specialized expertise

Resource Requirements and Real Costs

Personnel Costs (Annual)

• PostgreSQL Expert: $150k-250k salary, 3-6 months to find qualified candidate
• MySQL Developer: Standard full-stack developer salary, 1 week learning curve
• MariaDB Skills: Mid-level between MySQL and PostgreSQL complexity
• SQLite: Zero specialized knowledge until migration needed
• CockroachDB Expert: $200k+ salary, requires distributed systems background

Hidden First-Year Costs

• PostgreSQL: $15k-50k (consultants $200-400/hour, monitoring tools $500-2000/month)
• MySQL: $5k-20k (managed service premiums, backup automation)
• MariaDB: $8k-25k (smaller ecosystem, custom tooling, compatibility testing)
• SQLite: $2k-15k (plus inevitable migration costs)
• CockroachDB: $50k-200k+ (enterprise licensing, specialized training, complex monitoring)

Monthly Cloud Costs

• PostgreSQL Managed: $200-2000+
• MySQL Managed: $150-1500+
• MariaDB Managed: $200-1800+
• SQLite: $0 (embedded)
• CockroachDB: $3000-15000+ (starts at $3k/month for production)

Critical Failure Modes and Recovery

PostgreSQL Failure Scenarios

• Autovacuum Falls Behind: Query slowdown → manual vacuum tuning → consultant fees
• Connection Exhaustion: Application errors → PgBouncer installation → restart required
• Memory Issues: shared_buffers too high → OOM kills → requires expert tuning
• Recovery Difficulty: High - requires PostgreSQL expertise

MySQL Failure Scenarios

• Silent Data Truncation: Default permissive mode corrupts data → requires strict sql_mode
• Binary Log Disk Fill: Write blockage → manual cleanup → proper retention settings
• Slave Lag: Read inconsistency → identify blocking queries → restart replication
• Recovery Difficulty: Medium - well-documented solutions exist

SQLite Failure Scenarios

• Database Locked (SQLITE_BUSY): Too many concurrent writes → enable WAL mode or migrate
• File Growth: Doesn't auto-shrink → manual VACUUM → space reclaimed
• Recovery Difficulty: Low - copy file and restart application

CockroachDB Failure Scenarios

• Clock Skew: Transaction failures → NTP configuration → distributed coordination
• Network Partitions: Consistency delays → automatic resolution (usually)
• Recovery Difficulty: Low for common issues, impossible for edge cases without expertise

Performance Thresholds and Breaking Points

PostgreSQL Breaking Points

• Connection Limit: 100 default connections (process-based model)
• Memory Requirements: Minimum 4GB RAM for production, scales linearly
• Vacuum Performance: Falls behind on high-update workloads without tuning

MySQL Breaking Points

• Connection Limit: 151 default connections (thread-based model, more efficient)
• Memory Requirements: 2GB RAM sufficient for most workloads
• Replication Lag: Becomes problematic with large transactions or long-running queries

SQLite Breaking Points

• Concurrency: Single writer, multiple readers maximum
• File Size: Performance degrades after 1GB, unusable after 10GB
• Write Throughput: Becomes bottleneck with >10 concurrent write attempts

CockroachDB Breaking Points

• Cost Threshold: $3k/month minimum for production workloads
• Complexity: Requires distributed systems expertise for troubleshooting
• Network Requirements: High bandwidth between nodes, low latency critical

Migration Timeline Reality

SQLite → Other Databases: 2-4 weeks

• Export data (trivial)
• Schema modifications (minor)
• Connection code updates (straightforward)
• Concurrency testing (new bottlenecks discovered)

PostgreSQL ↔ MySQL/MariaDB: 3-6 months

• Schema differences (data types, constraints)
• Query compatibility (different SQL dialects)
• Application code changes (drivers, behaviors)
• Performance regression testing
• Always double timeline estimates, triple budget

Any Database → CockroachDB: 6-12 months minimum

• Complete architecture review
• Transaction model changes
• Distributed-friendly query patterns
• Team training on distributed concepts
• Probably hiring specialized personnel

Decision Framework Based on Team Reality

Choose SQLite When:

• Prototyping or single-user applications
• Data size < 1GB realistically
• Zero operational overhead required
• Can migrate later when growth demands it

Choose MySQL When:

• Team has limited database expertise
• Need reliability over advanced features
• Building typical web applications
• Want "boring" technology that works

Choose PostgreSQL When:

• Need advanced SQL features (window functions, CTEs, JSON)
• Have or can hire database expertise ($150k+ salary)
• Analytics/reporting workloads
• Data integrity more important than operational simplicity

Choose MariaDB When:

• Already on MySQL and need specific features
• Want better defaults than MySQL
• Acceptable to work with smaller ecosystem

Choose CockroachDB When:

• Actually need multi-continent distribution
• Unlimited budget and specialized team
• Exhausted all PostgreSQL scaling options
• Compliance requires specific consistency guarantees

Essential Troubleshooting Commands

PostgreSQL Emergency Commands

-- Memory issues
SELECT * FROM pg_stat_activity;
-- Statistics refresh
ANALYZE;
-- WAL log rotation when disk full
SELECT pg_switch_wal();
-- Query plan analysis
EXPLAIN (ANALYZE, BUFFERS) SELECT ...;

MySQL Emergency Commands

-- Connection debugging
SHOW PROCESSLIST;
-- Replication status
SHOW SLAVE STATUS\G;
-- Kill blocking queries
KILL QUERY [thread_id];
-- Binary log cleanup
PURGE BINARY LOGS BEFORE '2025-08-20 00:00:00';

SQLite Emergency Commands

-- Enable WAL mode for better concurrency
PRAGMA journal_mode=WAL;
-- Reclaim space after deletions
VACUUM;
-- Incremental cleanup
PRAGMA incremental_vacuum;

Version-Specific Warnings

Current Stable Versions (2024)

• PostgreSQL: 17.0 (parallel query deadlock bug)
• MySQL: 8.4.2 (binary log disk fill issue)
• MariaDB: 11.4.2 (JOIN operation changes)
• SQLite: 3.46.0 (improved WAL performance)
• CockroachDB: 24.1.4 (rapid release cycle)

Upgrade Risks

• PostgreSQL: Statistics targets changed, may need ANALYZE
• MySQL: Binary log retention settings critical
• MariaDB: Charset handling changes cause corruption
• SQLite: Generally backward compatible
• CockroachDB: Breaking changes common, enterprise support required

The Uncomfortable Truth

Most applications work fine on any of these databases. The choice matters less than:

• Proper implementation practices
• Adequate monitoring and alerting
• Team operational capabilities
• Realistic budget planning

Pick the database your team can operate successfully, not the one that wins benchmarks or has the coolest features.