Covers how to judge whether a company is cheap (valuation) and whether it earns well (quality) — formulas and interpretation of PER, PBR, PSR, ROE, ROA, and debt ratio.

Covers OHLCV data as the starting point of quant investing, the difference between simple and log returns, and the meaning of market capitalization.

A three-step pattern combining dual write and fallback read to transition data formats in live services without downtime.

How the CMK/DEK two-tier key structure in envelope encryption limits key leak impact and simplifies key rotation.

Which slot of the ML lifecycle each MLflow component fills, and which pieces a lightweight team can pick.

A Circuit Breaker’s trip trigger and recovery strategy must be designed together. Trip without recovery cuts the dependency permanently; recovery without a trip basis becomes meaningless cycling.

Before choosing a rate limit algorithm, the protection layer decides which algorithms are even available. This post lays out how L4/L7/Application layers and Token/Leaky/Sliding/Fixed algorithms intersect.

An external event drove ad traffic far above normal, triggering a cascading failure. The real problem was that the filtering component was a single point of failure — and the fallback sat on top of it too, so one collapse pulled both down at once. The fix took three paths: removing the fallback’s dependency (independence), adding rate limiting to the component itself (protection), and reconsidering the runtime (throughput).

sklearn and ONNX aren’t competing at the same layer. Once you separate their roles, the real question becomes ‘do I need an ONNX layer at all?’

The structure and characteristics of Logistic Regression, and why an old model still serves as the baseline in CTR prediction.