Topic
PostgreSQLIntermediateA reference comparison of PostgreSQL and MySQL: storage and MVCC, isolation defaults, DDL, data types, indexes, replication, licensing and tooling, with a decision summary.
#indexing#internals#replication
PostgreSQLBeginnerThe index exists, but the plan still shows a scan. Nine common reasons the optimizer can't (or shouldn't) use your index, and how to fix each one.
#execution-plans#indexing#performance
MongoDBIntermediateThe 100 MB blocking-sort limit means your index doesn't provide the sort order. Build compound indexes with the ESR rule, order pipeline stages correctly, and know when allowDiskUse is fine.
#indexing#nosql#performance
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
SQL ServerBeginnerThe single most important physical design decision in SQL Server, explained from first principles — with the queries to prove it.
#indexing#performance#schema-design
PostgreSQLIntermediateLearn to read PostgreSQL query plans node by node — estimates vs. actuals, loops, buffers — and turn them into index and query fixes.
#execution-plans#indexing#performance
MySQLIntermediateIn MySQL's InnoDB, the table is the primary key index. That single fact shapes insert speed, index size and how you should pick primary keys.
#indexing#internals#schema-design
