RedisAdvancedWhat changes at scale: stampede locks, probabilistic early refresh, stale-while-revalidate, hot keys, negative caching, pipelining, timeouts, circuit breakers, warmup, clustering and alerts.
#caching#nosql#performance
TiDBAdvancedSequential keys send every insert to one Region on one TiKV node. Spot the hotspot, then fix it with AUTO_RANDOM, SHARD_ROW_ID_BITS and pre-split Regions.
#performance#scalability#schema-design
RedisAdvancedEach Redis cache pattern with code, guarantees and failure modes, then the stale-set race, why delete beats update, versioned writes, outbox and CDC invalidation, and what to use for which data.
#caching#concurrency#nosql
MongoDBAdvancedA complete schema for a multi-tenant project tracker: collections, types, ESR indexes checked with explain(), validation, migrations, write concerns and sharding readiness.
#data-modeling#indexing#nosql
MongoDBAdvancedSeven ordered questions that decide embed, reference or a hybrid, the mechanical cost of each choice, and a help desk schema worked through end to end.
#data-modeling#nosql#schema-design
SQL ServerAdvancedA table-by-table workflow for tuning existing SQL Server indexes: find unused and overlapping indexes, merge them, and replace blanket rebuilds with statistics updates.
#db-administration#indexing#maintenance
PostgreSQLAdvancedExplains by mechanism where InnoDB or PostgreSQL does less work for lookups, updates, joins, connections and replication, then shows how to benchmark your own workload with pgbench and sysbench.
#internals#mvcc#performance
SQLiteAdvancedHow the -wal and -shm files, read marks and checkpoints work, why a WAL grows without bound, and how to set checkpointing, journal_size_limit and synchronous.
#concurrency#configuration#internals
PostgreSQLAdvancedA one-line migration can freeze every query on a table. lock_timeout, CREATE INDEX CONCURRENTLY, NOT VALID constraints and expand-and-contract keep schema changes online.
#indexing#locking#migrations
PostgreSQLAdvancedEvery UPDATE in PostgreSQL leaves a dead row behind. Here's how MVCC works under the hood, what VACUUM cleans up, and how to keep autovacuum ahead of your workload.
#concurrency#internals#maintenance
SQL ServerAdvancedError 1205 again? Pull the deadlock graph from the system_health session, read it like a DBA and fix the access pattern that causes it.
#concurrency#locking#troubleshooting