database-postgresql - SKILL.md Agent Skill

name: database-postgresql description: PostgreSQL database inspection and queries. Use when investigating table schemas, running queries, checking locks, replication status, or long-running queries. allowed-tools: Bash(python *)

PostgreSQL Database

Authentication

IMPORTANT: Uses DATABASE_URL or individual POSTGRES_HOST/POSTGRES_PORT/POSTGRES_DATABASE/POSTGRES_USER/POSTGRES_PASSWORD environment variables.

Configuration environment variables you CAN check (non-secret):

POSTGRES_HOST - Database host
POSTGRES_PORT - Database port (default: 5432)
POSTGRES_DATABASE - Database name
POSTGRES_SCHEMA - Default schema (default: public)

MANDATORY: Schema-First Investigation

Understand the schema before running queries.

LIST TABLES → DESCRIBE TABLE → EXECUTE QUERY → CHECK HEALTH

Available Scripts

All scripts are in .claude/skills/database-postgresql/scripts/

list_tables.py - List Tables (START HERE)

python .claude/skills/database-postgresql/scripts/list_tables.py [--schema public]

describe_table.py - Table Schema Details

python .claude/skills/database-postgresql/scripts/describe_table.py --table TABLE_NAME [--schema public]

execute_query.py - Run SQL Queries

python .claude/skills/database-postgresql/scripts/execute_query.py --query "SELECT * FROM users WHERE created_at > now() - interval '1 hour'" [--limit 100]

list_indexes.py - Index Information

python .claude/skills/database-postgresql/scripts/list_indexes.py [--table TABLE_NAME] [--schema public]

get_table_sizes.py - Table Size Analysis

python .claude/skills/database-postgresql/scripts/get_table_sizes.py [--table TABLE_NAME] [--schema public]

get_locks.py - Current Locks & Blocking Queries

python .claude/skills/database-postgresql/scripts/get_locks.py

get_replication_status.py - Replication Health

python .claude/skills/database-postgresql/scripts/get_replication_status.py

get_long_running_queries.py - Long-Running Queries

python .claude/skills/database-postgresql/scripts/get_long_running_queries.py [--min-duration 60]

Investigation Workflow

Lock Contention

1. get_locks.py (find blocking relationships)
2. get_long_running_queries.py --min-duration 30
3. execute_query.py --query "SELECT * FROM pg_stat_activity WHERE state = 'active'"

Replication Lag

1. get_replication_status.py (check lag_bytes/lag_seconds)
2. get_long_running_queries.py (queries blocking replication)

Table Growth Investigation

1. get_table_sizes.py (find largest tables)
2. list_indexes.py --table <table> (check index health)
3. describe_table.py --table <table>