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PostgreSQL

Port: 5433 (mapped from internal 5432) Version: PostgreSQL 15+ PostgreSQL is the primary database for all Coderz API services. It runs as a Docker container with persistent volume storage, managed via pgAdmin.

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Databases

DatabaseUserPasswordUsed By
coderapicoderapicoderapi_2024.NET API
postgrespostgres(default)Admin / system

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Connecting

From the host server: 
psql -h localhost -p 5433 -U coderapi -d coderapi
From inside Docker network (by container name): 
psql -h coderz-db -p 5432 -U coderapi -d coderapi
Connection string (.NET): 
Host=coderz-db;Port=5432;Database=coderapi;Username=coderapi;Password=coderapi_2024
Connection string (Python): 
postgresql://coderapi:coderapi_2024@coderz-db:5432/coderapi

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Common Operations

-- List all tables
\dt

-- Check database size
SELECT pg_size_pretty(pg_database_size('coderapi'));

-- Check table sizes
SELECT
  table_name,
  pg_size_pretty(pg_total_relation_size(table_name::text)) AS size
FROM information_schema.tables
WHERE table_schema = 'public'
ORDER BY pg_total_relation_size(table_name::text) DESC;

-- Check active connections
SELECT count(*) FROM pg_stat_activity WHERE state = 'active';

-- Find slow queries (> 1 second)
SELECT pid, now() - query_start AS duration, query
FROM pg_stat_activity
WHERE state = 'active' AND (now() - query_start) > interval '1 second';

-- Kill a slow query
SELECT pg_terminate_backend(pid) FROM pg_stat_activity WHERE pid = <pid>;

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Backup

# Backup the coderapi database
docker exec coderz-db pg_dump -U coderapi coderapi > /opt/coderz/backups/coderapi_$(date +%Y%m%d).sql

# Restore from backup
docker exec -i coderz-db psql -U coderapi coderapi < /opt/coderz/backups/coderapi_20260306.sql

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Monitoring PostgreSQL in Grafana

The .NET API Full Stack dashboard includes PostgreSQL panels showing:
  • Active connections count
  • Query rate (queries per second)
  • Cache hit ratio
  • Table sizes over time
These are collected by the postgres_exporter (if enabled) or via the .NET API’s built-in database metrics.

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Performance Tips

SettingDefaultRecommended for 4GB RAM server
shared_buffers128MB1GB (25% of RAM)
work_mem4MB64MB
max_connections10050–100
effective_cache_size4GB3GB
Add to docker-compose.yml: 
command: >
  postgres
  -c shared_buffers=1GB
  -c work_mem=64MB
  -c effective_cache_size=3GB