Systems Architecture — Questions¶

This file tracks big-picture, cross-module questions about Systems Architecture. For questions specific to a single module, use that module's QUESTIONS.md instead.

How to Use This File¶

1. Write questions immediately — when something is confusing, log it here before moving on.
2. Be specific — "I don't understand X" is less useful than "Why does X behave Y when Z?"
3. Update status as you find answers — partial answers count.
4. Link your answers to the module or resource where you found the explanation.
5. Add follow-up questions — good answers often raise better questions.

Status Legend¶

Question Format¶

### Q{{N}}: {{QUESTION_TITLE}}

**Asked:** {{YYYY-MM-DD}}
**Status:** 🔴 Unanswered

**Full question:**
Write the question in full. Include context about what prompted it.

**My current hypothesis:**
What do you think the answer might be, even if you're not sure?

**Answer:**
_To be filled in_

**Source:**
_Where did you find/confirm the answer?_

**Follow-up questions:**
- _Any new questions this answer raised_

Questions¶

Q001: When should I choose microservices over a monolith?¶

Asked: 2026-06-09 Status: 🟡 Partial

Full question: Everyone says microservices are the modern way to build, but I keep reading about teams going back to monoliths. What are the actual criteria for choosing one over the other? Is there a framework for making this decision?

My current hypothesis: Microservices seem better for large teams and high scale, but monoliths seem better for small teams and early-stage products. I'm not sure if this is the full picture.

Answer: Research in progress. See Module 01 and Module 04 for the trade-off framework.

Source: To be filled in

Follow-up questions: - What is a "distributed monolith" and why is it considered the worst of both worlds? - At what team size does the coordination overhead of microservices start to pay off?

Q002: What are the most common mistakes teams make when adopting distributed systems?¶

Asked: 2026-06-09 Status: 🔴 Unanswered

Full question: I want to understand the pitfalls before I develop bad habits or make expensive architectural mistakes. What do experienced architects wish they'd known earlier?

My current hypothesis: Based on the topic overview, I suspect the most common mistakes involve premature decomposition and underestimating the complexity of distributed transactions, but I haven't confirmed this.

Answer: To be filled in

Source: To be filled in

Follow-up questions: - How do I recognize a "distributed monolith" when I see one? - What does good service decomposition actually look like in practice?

Q003: How does the CAP theorem relate to the databases I already use?¶

Asked: 2026-06-09 Status: 🔴 Unanswered

Full question: I use PostgreSQL daily. I've heard of MongoDB and Cassandra. The quick reference says they all sit differently in CAP space. What does this mean practically — when would I actually see consistency vs. availability trade-offs in a real application?

My current hypothesis: I think CAP is more of a theoretical construct and in practice databases try to give you everything most of the time. The trade-offs only show up during failures.

Answer: To be filled in

Source: To be filled in

Follow-up questions: - Is the CAP theorem still relevant now that we have things like Google Spanner? - What is the PACELC model and how does it extend CAP?

Add new questions above this line. Keep them numbered sequentially.

Resolved Questions Archive¶

Move fully answered questions (🟢) here to keep the active list manageable.

(none yet)

Question Stats¶