--- name: postgresql-best-practices description: PostgreSQL development best practices for schema design, query optimization, and database administration metadata: maintainer: Mindrally source: https://github.com/Mindrally/skills --- # PostgreSQL Best Practices ## Core Principles - Leverage PostgreSQL's advanced features for robust data modeling - Optimize queries using EXPLAIN ANALYZE and proper indexing strategies - Use native PostgreSQL data types appropriately - Implement proper connection pooling and resource management - Follow PostgreSQL-specific security best practices ## Schema Design ### Data Types - Use appropriate native types: `UUID`, `JSONB`, `ARRAY`, `INET`, `CIDR` - Prefer `TIMESTAMPTZ` over `TIMESTAMP` for timezone-aware applications - Use `TEXT` instead of `VARCHAR` when no length limit is needed - Consider `NUMERIC` for precise decimal calculations (financial data) - Use `SERIAL` or `BIGSERIAL` for auto-incrementing IDs, or `UUID` for distributed systems ```sql CREATE TABLE orders ( order_id UUID PRIMARY KEY DEFAULT gen_random_uuid(), customer_id UUID NOT NULL REFERENCES customers(customer_id), order_data JSONB NOT NULL DEFAULT '{}', tags TEXT[] DEFAULT '{}', total_amount NUMERIC(12, 2) NOT NULL, created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(), updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW() ); ``` ### Table Design - Always define primary keys - Use foreign keys with appropriate ON DELETE/UPDATE actions - Add NOT NULL constraints where appropriate - Use CHECK constraints for data validation - Consider partitioning for large tables ```sql CREATE TABLE products ( product_id SERIAL PRIMARY KEY, sku VARCHAR(50) NOT NULL UNIQUE, name TEXT NOT NULL, price NUMERIC(10, 2) NOT NULL CHECK (price >= 0), status VARCHAR(20) NOT NULL DEFAULT 'active' CHECK (status IN ('active', 'inactive', 'discontinued')), metadata JSONB DEFAULT '{}' ); ``` ### Partitioning - Use declarative partitioning for large tables (millions of rows) - Choose appropriate partition strategy: RANGE, LIST, or HASH - Create indexes on partitioned tables after partitioning ```sql CREATE TABLE events ( event_id BIGSERIAL, event_type VARCHAR(50) NOT NULL, payload JSONB, created_at TIMESTAMPTZ NOT NULL ) PARTITION BY RANGE (created_at); CREATE TABLE events_2024_q1 PARTITION OF events FOR VALUES FROM ('2024-01-01') TO ('2024-04-01'); ``` ## Indexing Strategies ### Index Types - Use B-tree indexes (default) for equality and range queries - Use GIN indexes for JSONB, arrays, and full-text search - Use GiST indexes for geometric data and range types - Use BRIN indexes for large, naturally ordered data - Consider partial indexes for filtered queries ```sql -- B-tree index for common lookups CREATE INDEX idx_orders_customer ON orders(customer_id); -- GIN index for JSONB queries CREATE INDEX idx_orders_data ON orders USING GIN (order_data); -- Partial index for active records only CREATE INDEX idx_active_products ON products(name) WHERE status = 'active'; -- Covering index to avoid table lookup CREATE INDEX idx_orders_covering ON orders(customer_id) INCLUDE (order_date, total_amount); ``` ### Index Maintenance - Regularly run ANALYZE to update statistics - Use REINDEX for bloated indexes - Monitor index usage with `pg_stat_user_indexes` - Remove unused indexes to reduce write overhead ```sql -- Check index usage SELECT schemaname, relname, indexrelname, idx_scan, idx_tup_read FROM pg_stat_user_indexes ORDER BY idx_scan ASC; ``` ## Query Optimization ### EXPLAIN ANALYZE - Always analyze query plans for slow queries - Look for sequential scans on large tables - Identify missing indexes from query plans - Watch for high row estimates vs actual rows ```sql EXPLAIN (ANALYZE, BUFFERS, FORMAT TEXT) SELECT c.name, COUNT(o.order_id) FROM customers c LEFT JOIN orders o ON c.customer_id = o.customer_id WHERE c.created_at > '2024-01-01' GROUP BY c.customer_id, c.name; ``` ### Common Table Expressions (CTEs) - Use CTEs for complex query organization - Note: CTEs are optimization fences in older PostgreSQL versions - Use `MATERIALIZED`/`NOT MATERIALIZED` hints in PostgreSQL 12+ ```sql WITH recent_orders AS MATERIALIZED ( SELECT customer_id, COUNT(*) AS order_count, SUM(total) AS total_spent FROM orders WHERE order_date > CURRENT_DATE - INTERVAL '30 days' GROUP BY customer_id ) SELECT c.name, ro.order_count, ro.total_spent FROM customers c JOIN recent_orders ro ON c.customer_id = ro.customer_id WHERE ro.total_spent > 1000; ``` ### Window Functions - Use window functions for analytics queries - Leverage PARTITION BY and ORDER BY for complex calculations ```sql SELECT order_id, customer_id, total_amount, SUM(total_amount) OVER (PARTITION BY customer_id ORDER BY order_date) AS running_total, ROW_NUMBER() OVER (PARTITION BY customer_id ORDER BY order_date DESC) AS order_rank FROM orders; ``` ## JSONB Best Practices - Use JSONB over JSON for better performance and indexing - Create GIN indexes for JSONB columns you query - Use containment operators (@>, <@) for efficient queries - Extract frequently queried fields to regular columns ```sql -- Efficient JSONB query with GIN index SELECT * FROM products WHERE metadata @> '{"category": "electronics"}'; -- Extract specific fields SELECT product_id, metadata->>'brand' AS brand, (metadata->>'rating')::numeric AS rating FROM products WHERE metadata ? 'rating'; ``` ## Connection Management ### Connection Pooling - Use PgBouncer or pgpool-II for connection pooling - Set appropriate pool sizes based on workload - Use transaction pooling mode for short-lived connections ### Connection Settings ```sql -- Recommended session settings SET statement_timeout = '30s'; SET lock_timeout = '10s'; SET idle_in_transaction_session_timeout = '60s'; ``` ## Transactions and Locking - Use appropriate transaction isolation levels - Keep transactions short to reduce lock contention - Use advisory locks for application-level locking - Monitor and resolve lock conflicts ```sql -- Use advisory locks for application coordination SELECT pg_advisory_lock(hashtext('resource_name')); -- Do work SELECT pg_advisory_unlock(hashtext('resource_name')); -- Check for blocking queries SELECT blocked_locks.pid AS blocked_pid, blocking_locks.pid AS blocking_pid, blocked_activity.query AS blocked_query FROM pg_catalog.pg_locks blocked_locks JOIN pg_catalog.pg_locks blocking_locks ON blocking_locks.locktype = blocked_locks.locktype AND blocking_locks.relation = blocked_locks.relation AND blocking_locks.pid != blocked_locks.pid JOIN pg_catalog.pg_stat_activity blocked_activity ON blocked_activity.pid = blocked_locks.pid; ``` ## Maintenance ### Vacuum and Analyze - Enable autovacuum and tune for your workload - Run manual VACUUM ANALYZE after bulk operations - Monitor table bloat ```sql -- Check table bloat SELECT schemaname, relname, n_live_tup, n_dead_tup, round(n_dead_tup * 100.0 / nullif(n_live_tup + n_dead_tup, 0), 2) AS dead_pct FROM pg_stat_user_tables WHERE n_dead_tup > 1000 ORDER BY n_dead_tup DESC; ``` ### Backup Strategies - Use pg_dump for logical backups - Use pg_basebackup for physical backups - Implement point-in-time recovery (PITR) with WAL archiving - Test backup restoration regularly ## Security - Use SSL/TLS for connections - Implement row-level security (RLS) for multi-tenant applications - Use roles and GRANT/REVOKE for access control - Audit sensitive operations with pgAudit extension ```sql -- Enable row-level security ALTER TABLE documents ENABLE ROW LEVEL SECURITY; CREATE POLICY documents_tenant_policy ON documents FOR ALL USING (tenant_id = current_setting('app.tenant_id')::uuid); -- Grant minimal privileges GRANT SELECT, INSERT, UPDATE ON orders TO app_user; GRANT USAGE ON SEQUENCE orders_order_id_seq TO app_user; ``` ## Monitoring - Monitor with pg_stat_statements extension - Track slow queries and optimize regularly - Set up alerts for replication lag, connection count, and disk usage - Use pg_stat_activity to monitor active queries ```sql -- Enable pg_stat_statements CREATE EXTENSION IF NOT EXISTS pg_stat_statements; -- Find slow queries SELECT query, calls, mean_exec_time, total_exec_time FROM pg_stat_statements ORDER BY mean_exec_time DESC LIMIT 10; ``` --- Source attribution: Mindrally Original project: https://github.com/Mindrally/skills/blob/7682ca77710e0971eab4e0ae5dddfa281aea0ba5/postgresql-best-practices/SKILL.md License: Apache-2.0 License information: https://www.apache.org/licenses/LICENSE-2.0 Original upstream instructions; downloaded from Mega AI Hub. ## Upstream license notice Apache License Version 2.0, January 2004 http://www.apache.org/licenses/ TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 1. 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See the License for the specific language governing permissions and limitations under the License. # Mega AI Hub resource metadata Creator / publisher: Mindrally Original project: https://github.com/Mindrally/skills/blob/7682ca77710e0971eab4e0ae5dddfa281aea0ba5/postgresql-best-practices/SKILL.md Attribution basis: Source repository record Fields of work: Data & Analytics, Development & Engineering Roles: Data Analyst, Data Scientist, Database Administrator Specialties: Database Tools: PostgreSQL Country applicability: Country not specified Classification basis: Source catalog labels Instruction SHA-256: 77bfa60c38b83a735f47c754a860a32f03763cdd3dbdbb1a6bece0c490256cb5