# Database Issues Troubleshooting Guide

**Last Updated**: 2025-10-22

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## Connection Issues

### Symptom: `could not connect to server`

**Diagnosis**:
```bash
# Check PostgreSQL is running
kubectl get pods -n foxhunt -l app=postgresql

# Check service endpoint
kubectl get endpoints -n foxhunt foxhunt-postgresql

# Test connectivity
kubectl run -it --rm psql-test --image=postgres:15 --restart=Never -- \
    psql -h foxhunt-postgresql.foxhunt.svc.cluster.local -U foxhunt -d foxhunt
```

**Resolution**:
```bash
# Restart PostgreSQL
kubectl delete pod foxhunt-postgresql-0 -n foxhunt

# Verify secrets
kubectl get secret foxhunt-secrets -n foxhunt -o yaml
```

---

## Slow Queries

### Symptom: Queries taking >1s

**Diagnosis**:
```sql
-- Find slow queries
SELECT query, mean_exec_time, calls 
FROM pg_stat_statements 
ORDER BY mean_exec_time DESC 
LIMIT 10;

-- Analyze query plan
EXPLAIN ANALYZE SELECT * FROM orders WHERE symbol='ES.FUT' ORDER BY created_at DESC LIMIT 100;
```

**Resolution**:
```sql
-- Create index
CREATE INDEX CONCURRENTLY idx_orders_symbol_created_at ON orders(symbol, created_at DESC);

-- Update statistics
ANALYZE orders;

-- Increase work_mem for complex queries
SET work_mem = '256MB';
```

---

## Deadlocks

### Symptom: `deadlock detected`

**Diagnosis**:
```sql
-- Check deadlock log
SELECT * FROM pg_stat_activity WHERE wait_event_type = 'Lock';

-- Enable deadlock logging
ALTER SYSTEM SET deadlock_timeout = '1s';
ALTER SYSTEM SET log_lock_waits = on;
SELECT pg_reload_conf();
```

**Resolution**:
```sql
-- Access tables in consistent order
BEGIN;
SELECT * FROM orders WHERE id = 1 FOR UPDATE;  -- Always lock orders first
SELECT * FROM positions WHERE order_id = 1 FOR UPDATE;  -- Then positions
COMMIT;
```

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**End of Database Issues Troubleshooting Guide**