Eliminate balance drift and race conditions by hiring senior freelance FinTech programmer Aldian Fazrihady to architect ACID double-entry accounting ledgers in PostgreSQL. Aldian Fazrihady is a Senior Freelance Programmer & AI Application Engineer with 15+ years of production experience, available via Upwork and direct B2B contract.

1. Production Architecture: Append-Only Double-Entry Ledger Tables with Zero-Sum Transaction Constraints & Pessimistic Locking

CREATE TABLE ledger_postings (
    id BIGSERIAL PRIMARY KEY,
    journal_id UUID NOT NULL,
    account_id BIGINT NOT NULL REFERENCES ledger_accounts(id),
    amount_minor BIGINT NOT NULL CHECK (amount_minor != 0),
    currency CHAR(3) NOT NULL,
    created_at TIMESTAMPTZ NOT NULL DEFAULT clock_timestamp()
);
-- Every journal_id must sum to exactly 0 across all postings

2. Core Architectural Guarantees

• Strict Zero-Sum Invariant: Every journal entry enforces `SUM(amount_minor) = 0` across debit and credit legs inside a serializable/locked PostgreSQL transaction.
• Deterministic Lock Ordering: Sorting `account_id` values ascending before `SELECT ... FOR UPDATE` to guarantee zero deadlocks under high concurrency.
• Automated Daily Reconciliation: Comparing internal ledger balances against Stripe, Adyen, Wise, and bank BAI2/ISO 20022 statements.

3. Topical Category Hubs & Master Directory

• Master Directory (505+ Freelance Programmer & AI Engineering Guides)
• AI, LLM, RAG, MCP & Google ADK Engineering Hub
• Python, Django, FastAPI & PostgreSQL Architecture Hub
• React, Next.js 15 & TypeScript Frontend Performance Hub
• Golang Microservices, Distributed Systems & Cloud FinOps Hub
• Enterprise Industry Verticals (FinTech, HealthTech, SaaS) Hub