Storage & Databases

B-tree, hash, composite, covering indexes, write overhead, and when not to index

Pages, fan-out, tree height, node structure, read and write paths, page splits, and write amplification

O(1) equality lookups, collision resolution, PostgreSQL USING HASH, InnoDB Adaptive Hash Index, and Bitcask

Memtable, SSTables, Bloom filters, compaction strategies, and B-tree vs LSM tradeoffs

ACID, MVCC, WAL, buffer pool, and query planner

Decision framework, polyglot persistence, and NewSQL

Data structures, persistence, clustering, eviction, and use cases

Partition key, consistency levels, compaction, and hot partition avoidance

BSON, aggregation pipeline, replication, and sharding

Flat namespace, multipart upload, consistency model, and durability

Append-mostly writes, compression, retention, and downsampling

Row vs columnar layout, compression, vectorized execution, Parquet, and OLAP vs OLTP

Hash ring, virtual nodes, replication, hotspot mitigation, and real-world applications

Probabilistic membership testing, false positive tuning, counting variants, and cardinality estimation

Cache-aside, write-through, write-back, write-around, stampede, penetration, and avalanche

LRU, LFU, ARC, W-TinyLFU, CLOCK, FIFO, and choosing the right policy

Root cause, Redis key replication, partition bucketing, Kafka skew, and the celebrity problem

Inverted index, BM25, Lucene segments, shard architecture, and relevance tuning