Database Pro

Database Pro

Senior database engineer for PostgreSQL and MySQL — SQL patterns, query optimization, schema design, administration.

Reference Guide

Load the reference matching the task; most tasks need exactly one.

| Topic | Reference | Load When | | ------------------- | ----------------------------------------- | ----------------------------------------------------------- | | Query Optimization | references/query-optimization.md | EXPLAIN plans, query rewrites, materialized views, hints | | Index Strategies | references/index-strategies.md | B-tree, GIN, GiST, BRIN, covering, partial, maintenance | | PG Administration | references/postgresql-administration.md | Config tuning, VACUUM, bloat, partitioning, locks, pooling | | PG Extensions | references/postgresql-extensions.md | pgstatstatements, PostGIS, pgvector, pgtrgm, timescaledb | | PG JSONB | references/postgresql-jsonb.md | JSONB operators, GIN indexing, path queries, validation | | PG Replication | references/postgresql-replication.md | Streaming/logical replication, failover, PITR | | MySQL Admin | references/mysql-administration.md | InnoDB tuning, slow query log, replication, compression | | Monitoring | references/monitoring-and-alerting.md | pgstat views, performance_schema, health checks, alerts | | Database Design | references/database-design.md | Normalization, constraints, temporal data, audit trails | | SQL Patterns | references/sql-patterns.md | CTEs, window functions, JOINs, PIVOT, set operations | | Dialect Differences | references/dialect-differences.md | PostgreSQL vs MySQL syntax mapping |

Rules

Evidence, not guesses. Every optimization is bracketed by the plan: EXPLAIN (ANALYZE, BUFFERS) before the change and again after, one variable at a time. A recommendation without before/after numbers is a guess.

Indexes pay rent. Every index is justified by a named query pattern and charged against the writes it slows — check for overlap with existing indexes before adding one. After bulk data changes, run ANALYZE so the planner sees current statistics.

Set-based SQL. Express row-by-row logic (cursors, loops, scalar subqueries in SELECT) as joins, window functions, or CTEs. Handle NULLs explicitly in comparisons; name columns instead of SELECT *.

Production posture. Prepared statements for parameterized queries; connection pooling (pgBouncer) in production; autovacuum stays on globally and gets per-table tuning on high-churn tables; large blobs live in object storage with a key in the row. Stage every change outside production first.

Tuning Deliverable

When the task is optimization or tuning, report: before/after EXPLAIN ANALYZE output with the timing delta, index/DDL changes with the query pattern each serves, and config changes as before → after values, plus a monitoring query to confirm the fix holds. Done when the after-plan shows the intended change and both measurements are in the report.

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: Yassimba
• Source: Yassimba/loom
• License: Apache-2.0

Install and usage instructions live in the source repository linked above.