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Achievement: Pull SharkAchievement: YOLOAchievement: Quickdraw

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@emap2021

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victormends/README.md

João Victor Mendes

"I treat production behavior as the real specification: isolate variables, find root causes, fix structurally so the failure class cannot recur."

Typing SVG

LinkedIn   Résumé

Location   Current employer   English

Impact Highlights


PostgreSQL & Database Engineering

  • Eliminated 100% of WAL data losses across 500+ environments by querying pg_replication_slots, identifying an orphaned slot holding WAL segments for a decommissioned subscriber, and enforcing max_slot_wal_keep_size as a fleet-wide guardrail.
  • Cut restore time 60% (17 min to 6:58) on a 15GB+ database via pg_restore -j 4 parallel processing. Traced 1GB/month disk bloat through pg_class and pg_toast to encrypted paths serialized as thousands of characters per audit log entry.
  • Automated 30-database cluster recovery with a PowerShell script that parallelizes state checks, clears stale postmaster.pid files, and handles WAL recovery on boot. Recovery cut from hours to under 5 minutes, daily support calls to near-zero.
  • Restored database access fleet-wide after a pg_hba.conf SCRAM-SHA-256 vs MD5 mismatch, applying scoped MD5 by IP range while preserving SCRAM everywhere else.

Automation & Data Engineering

  • Engineered a 70M-record ETL pipeline in a single day using PL/pgSQL + PowerShell against a 15GB+ government dataset. Unlogged tables and dynamic SQL cut processing time 60%, surfacing the top 0.001% of leads that drove Q3 commercial strategy.
  • Compressed fiscal invoice diagnosis from 30+ min to under 5 min using LLM-assisted XML parsing of raw SEFAZ rejection messages across NCM, CFOP, ICMS, and CBNEF formats, eliminating an entire class of developer escalations.
  • Zero data-loss legacy migration: reverse-engineered a Firebird database with no documentation in an afternoon, replaying 20 years of transaction history (10,000+ items, 500k BRL) from first principles to reconstruct current inventory state.

Early signal: OBMEP Silver Medal (2016), Bronze (2014), 2x Honorable Mentions; top 0.01% among 18M+ participants nationally.


 
name:              João Victor Mendes
role:              L2/L3 Technical Support Engineer
company:           Pedroso Automação  # B2B fiscal compliance ERP SaaS
location:          União da Vitória, PR, Brazil

specialty:         [PostgreSQL, Incident Response, ETL, Windows Server Automation]
clients:           500+ corporate  # 1500+ end-users
proof_point:       OBMEP Silver Medal  # top 0.01% among 18M+ participants

featured_now:
  - "receita-cnpj-etl-pipeline  # Receita CNPJ ETL + PostgreSQL client classifier"
  - "incident-response-runbook  # PostgreSQL incident response + NVC + post-mortems"
  - "pg-incident-recovery      # Windows-first PostgreSQL multi-cluster recovery tool"

open_to:           [Support Engineering, Database Engineering, SRE]
contact:           linkedin.com/in/mendes-victor

Portfolio Map

Area Public artifact What it demonstrates
Data engineering receita-cnpj-etl-pipeline Windows-first ETL for Receita Federal CNPJ open data, PostgreSQL staging, large-file classification, sanitized release packaging
Incident response incident-response-runbook PostgreSQL severity classification, triage, communication, escalation, and post-mortem structure
Recovery automation pg-incident-recovery Safe Windows service recovery boundaries for PostgreSQL crash-recovery scenarios
Restore tooling pg-restore-tool Operator-controlled local restore flow with explicit safe/fast/unsafe profiles
Deployment automation windows-postgres-deployment-installer Human-reviewed PostgreSQL deployment automation for Windows workstations and small servers
Fiscal support utilities nfe-xml-organizer, tls-fix-erp-updater Practical PowerShell utilities around NF-e file handling and Windows TLS registry failure modes
Data visualization one-piece-ratings-timeline Static-site data product, source policy, scheduled refresh, and GitHub Pages publishing

Featured Repos

incident-response-runbook

incident-response-runbook

A production-grade PostgreSQL incident response framework that combines:

  • WAL disk exhaustion recovery (pg_wal zero bytes free)
  • SCRAM/MD5 and pg_hba.conf authentication failures
  • Connection pool exhaustion and lock contention diagnosis
  • Worked post-mortems for both infra and application-layer incidents
  • NVC-based client communication and war-room protocols

This is the clearest public artifact of how I approach production systems: diagnose from first principles, document the failure mode precisely, and encode the fix so the class of incident does not recur.

pg-incident-recovery

pg-incident-recovery

A Windows-first PostgreSQL recovery orchestrator for multi-cluster hosts. It automates the safe parts of post-reboot incident handling:

  • discovery of stopped PostgreSQL services
  • data-directory resolution from service definitions
  • stale postmaster.pid cleanup
  • pg_controldata-based missing WAL triage
  • parallel startup with bounded retries
  • crash-recovery monitoring and clean handoff back to Windows SCM
  • persistent queue files so interrupted runs can resume cleanly

This is the executable complement to the runbook repo: the runbook explains how I reason about incidents; this tool shows how I automate one of the ugliest recovery paths without crossing into unsafe automation.

Deployment and Restore Utilities

windows-postgres-deployment-installer and pg-restore-tool cover the less glamorous support paths around PostgreSQL: workstation/small-server deployment, local rebuilds, restore profiles, and operator-reviewed automation. They are deliberately scoped tools rather than platform claims: the goal is to remove repetitive failure-prone steps while keeping destructive choices explicit.

Technical Stack

PostgreSQL   PowerShell   Python   AWS   Git   Windows Server   Bash

WAL Management PL/pgSQL EXPLAIN ANALYZE Replication Slots Bloat Analysis autovacuum

ITIL RCA P1/P2 Incident Response ETL Pipeline Design NF-e / CT-e / SEFAZ pg_hba / SCRAM / RBAC

Education


FGV — Data Science & Economics (2020-2022) Full-ride OBMEP scholarship

IFPR — Systems Analysis & Development (2023-2024) Grade A in Mathematics for Computing

Public artifacts are sanitized: no client data, private hostnames, credentials, or internal support tickets.

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  1. receita-cnpj-etl-pipeline receita-cnpj-etl-pipeline Public

    Windows-first PowerShell ETL pipeline for Receita Federal CNPJ open data using PostgreSQL.

    PowerShell

  2. brazil-ncm-table-tools brazil-ncm-table-tools Public

    Windows-first .NET and PowerShell tools to download and convert Brazil's official NCM table for ERP/search workflows.

    C#

  3. pg-incident-recovery pg-incident-recovery Public

    Windows-first PostgreSQL recovery orchestrator for multi-cluster hosts, with bounded retries, crash-recovery monitoring, WAL triage, and persistent state.

    PowerShell

  4. incident-response-runbook incident-response-runbook Public

    Production-grade incident response framework for PostgreSQL environments that treats communication failure as a first-class technical problem.

    1

  5. one-piece-ratings-timeline one-piece-ratings-timeline Public

    Fan-made One Piece ratings timeline grouped by saga, with IMDb-sourced ratings

    PowerShell

  6. windows-postgres-deployment-installer windows-postgres-deployment-installer Public

    Windows-first PostgreSQL deployment automation for operator-reviewed workstation and small-server installs.

    PowerShell