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Concepts

Database Types

Every database is optimized for a different access pattern. Pick the wrong one and no amount of tuning saves you.

Key-Value Stores

Redis and Memcached internals — when O(1) lookup is all you need and when it becomes a liability.

RedisMemcachedTTLEviction

Document Stores

MongoDB internals — document model, embedding vs referencing, indexes, replication and sharding.

MongoDBEmbeddingIndexesReplication

Cassandra, Bigtable, and DynamoDB — wide-column storage, ring architecture, and query-first data modeling.

CassandraBigtableDynamoDBRow Keys

Why SQL LIKE fails at scale. Inverted indexes, TF-IDF ranking, and Elasticsearch architecture.

Inverted IndexTF-IDFBM25Elasticsearch

Graph Databases

When relationships are the data. Graph models, Cypher queries, and the use cases where SQL joins collapse.

Graph ModelCypherNeo4jTraversal

Object storage model, presigned URLs, multipart uploads, content-addressable storage, and chunk deduplication.

S3 ModelPresigned URLsMultipartDeduplication

Google Spanner internals — TrueTime, external consistency, and when NewSQL beats both Postgres and NoSQL.

SpannerTrueTimeExternal ConsistencyCockroachDB

Transactional vs analytical workloads. ETL pipelines, data warehouses, and when to stop querying production.

Choosing The Right DB

A decision framework for picking between SQL, NoSQL, and specialized stores based on access patterns and constraints.

Decision FrameworkAccess PatternsTrade-offsCheatsheet

Entities, relationships, access patterns, and schema design. From blank page to a model that survives real traffic.

EntitiesAccess PatternsSchema DesignInstagram Schema