Databases cheat sheets

Databases cheat sheets on Sefism, written by Tauseef Fayyaz: every concept in plain words, why it is used and the pitfall that catches people out.

76 sheets
5120 concepts

Free to learn. Credits keep it fair.

Reading is free. Adding a roadmap, keeping a cheat sheet or asking Tauseef a question uses credits, which only make sure the platform goes to people who are actually learning.

15creditswhen you join
1stroadmapfree to add
Morecreditson request, as you learn

Foundations

Start here if you are new or your basics are patchy.

Cheat sheet · Foundations
SQL and databases cheat sheet
Queries, design, indexes, transactions.
Chapters
1. 1Relational model and your setup
2. 2Querying one table
3. Joins and set operations
+ 6 more
- 9 chapters
- 77 concepts
Opens with credits
Cheat sheet · Foundations
MongoDB cheat sheet
Documents, modelling, indexes, aggregation.
Chapters
1. 1Documents and your setup
2. 2Reading and writing documents
3. Arrays and nested documents
+ 5 more
- 8 chapters
- 77 concepts
Opens with credits

Build products

Ship real apps for the web and phones.

Cheat sheet · Build products
Choosing the right database cheat sheet
SQL, document, cache, search, vector and more.
Chapters
1. 1Start from the data
2. 2Relational databases
3. Document databases
+ 7 more
- 10 chapters
- 78 concepts
Opens with credits

Specialise

Go deep in one area of engineering.

Cheat sheet · Specialise
Data engineering cheat sheet
Pipelines, warehouses, Spark, dbt.
Chapters
1. 1Foundations and ingestion
2. 2Analytical SQL and data modelling
3. File formats, lakes and lakehouses
+ 7 more
- 10 chapters
- 77 concepts
Opens with credits
Cheat sheet · Specialise
Vector databases cheat sheet
Embeddings, similarity metrics, ANN indexes, filtering, hybrid search, reranking, RAG chunking, pgvector, dedicated stores and evaluation.
Chapters
1. 1Embeddings and similarity
2. 2Nearest neighbour search
3. Index types: HNSW, IVF and PQ
+ 6 more
- 9 chapters
- 64 concepts
Opens with credits

Browse the cheat sheets by topic

Each of these is its own page: the foundations shelf, the career shelf, the sheets that are open end to end. The filters above do the same thing without a page load.

Work with me

Stuck on something specific?

Writing only gets you so far. If you want an answer to your situation rather than the general case, book a session and we will work through it together. Sessions are free for approved Sefism members, and a few slots open each week.