Questions — Module 01: Introduction to PostgreSQL¶
Log questions as they arise — don't wait until you understand them fully. A question written down is a learning opportunity captured. For big-picture questions about the whole topic, use the topic-level QUESTIONS.md instead.
How to Use This File¶
- Write the question the moment it occurs to you, even if you can't articulate it well yet.
- Come back and refine the question once you understand it better.
- Update the status as you research or find answers.
- Link to the source where you found the answer.
- Capture follow-up questions — good answers always raise new ones.
Status Legend¶
| Symbol | Meaning |
|---|---|
| 🔴 | Unanswered — needs active research |
| 🟡 | Partial — have some understanding, still incomplete |
| 🟢 | Answered — well understood, could explain to someone else |
| ⏸ | Deferred — not urgent, revisit in a later module |
Questions¶
Q001: Why does PostgreSQL use the term "relation" instead of "table"?¶
Asked: 2026-06-09 Status: 🟡 Partial
Full question: The module README uses both "relation" and "table." Are they exactly the same thing? When would I use one term vs. the other?
My current hypothesis: I think "relation" is the mathematical/theoretical term from Codd's paper, and "table" is the everyday practical term for the same thing. They seem interchangeable in practice.
Answer: To be filled in
Source / Confirmed by: To be filled in
Follow-up questions: - Does the PostgreSQL documentation consistently use "relation" or "table"?
Q002: What exactly happens when I type \dt in psql vs. when I type a SQL statement?¶
Asked: 2026-06-09 Status: 🔴 Unanswered
Full question:
The module mentions that psql meta-commands (starting with \) are "processed by psql itself and never sent to the server." So what does \dt actually do? Does it run a SQL query behind the scenes? How does it know what tables exist?
My current hypothesis:
I think \dt probably runs a SQL query against PostgreSQL's internal system tables (like pg_class or information_schema.tables) but psql handles this automatically so I don't have to write the query myself.
Answer: To be filled in
Source / Confirmed by: To be filled in
Follow-up questions:
- Can I see the SQL that psql uses for \dt? (I think you can with \set ECHO_HIDDEN on)
Add new questions below this line. Keep them numbered sequentially.
Resolved Questions Archive¶
Move fully answered 🟢 questions here to keep the active list clean.
(none yet)
Question Stats¶
| Status | Count |
|---|---|
| 🔴 Unanswered | 1 |
| 🟡 Partial | 1 |
| 🟢 Answered | 0 |
| ⏸ Deferred | 0 |
| Total | 2 |