HeliosDB Performance Tuning Playbook¶

Version: 1.0 Last Updated: 2025-11-30

Performance Assessment¶

-- Baseline query performance
SELECT * FROM performance_baseline_report;

-- Identify slow queries
SELECT
  query,
  execution_count,
  avg_time_ms,
  max_time_ms
FROM pg_stat_statements
ORDER BY avg_time_ms DESC
LIMIT 20;

Scenario 1: Slow SELECT Queries¶

Problem: SELECT queries taking >1 second

Diagnosis:

EXPLAIN ANALYZE SELECT ...;
-- Look for Seq Scan on large tables

Solutions:

-- 1. Add indexes
CREATE INDEX idx_col ON table(column);

-- 2. Optimize JOIN order (use hints)
SELECT /*+ LEADING(t1 t2) */ ...

-- 3. Use quantum optimizer for complex queries
SELECT /*+ OPTIMIZER(quantum) */ ...

-- 4. Enable query cache
ALTER TABLE frequently_queried ENABLE INTELLIGENT_CACHING;

Scenario 2: Slow Aggregations¶

Problem: GROUP BY, SUM, COUNT taking too long

Solutions:

-- 1. Create materialized view
CREATE MATERIALIZED VIEW summary AS
SELECT date, SUM(amount) FROM orders GROUP BY date;

-- 2. Enable parallel aggregation
SET max_parallel_workers = 4;

-- 3. Pre-aggregate data
CREATE TABLE daily_summary AS
SELECT DATE(order_date), SUM(amount)
FROM orders
GROUP BY DATE(order_date);

Scenario 3: High Memory Usage¶

Problem: Database consuming too much memory

Solutions:

-- 1. Reduce cache size
ALTER DATABASE SET CACHE_PARAMS (max_size_mb = 1024);

-- 2. Limit work_mem
SET work_mem = '64MB';

-- 3. Monitor memory
SELECT * FROM memory_usage_report;

Scenario 4: High Disk I/O¶

Problem: Excessive disk reads

Solutions:

-- 1. Enable caching
ALTER TABLE large_table ENABLE INTELLIGENT_CACHING;

-- 2. Optimize storage
VACUUM FULL large_table;
REINDEX table_name;

-- 3. Use BRIN indexes for large tables
CREATE INDEX idx_large USING BRIN(id);

Scenario 5: Replication Lag¶

Problem: Replicas falling behind

Solutions:

-- 1. Check lag
SELECT MAX(pg_wal_lsn_diff(pg_current_wal_lsn(), replay_lsn))
FROM pg_stat_replication;

-- 2. Increase wal_keep_size
ALTER SYSTEM SET wal_keep_size = '2GB';

-- 3. Use asynchronous replication if lag acceptable
ALTER SYSTEM SET synchronous_commit = off;

Regular Maintenance¶

-- Daily
ANALYZE;
VACUUM;

-- Weekly
REINDEX;
ANALYZE;

-- Monthly
VACUUM FULL;
CLUSTER;

Monitoring¶

-- Performance dashboard
SELECT * FROM performance_overview;

-- Query performance trends
SELECT * FROM query_performance_history
WHERE measure_date >= NOW() - INTERVAL '7 days';

Best Practices¶

Create indexes on frequently filtered columns
Use EXPLAIN ANALYZE before optimizing
Monitor query performance trends
Cache hot data
Partition large tables
Regular maintenance
Test performance changes

Related Documentation: - Query Optimization Guide - Index Strategy Guide