Topic
PostgreSQLBeginnerHow to choose between PostgreSQL, MySQL, SQLite and MongoDB for a web app, where Redis and a search engine fit, a decision table by app type, and when the PostgreSQL default is wrong.
#data-modeling#scalability#schema-design
The old UUID performance problem came from UUIDv4's randomness, not UUIDs themselves. How UUIDv7 changes the trade-off, what the extra 8 bytes still cost and when to pick each.
#data-types#indexing#schema-design
GeneralIntermediateAdjacency lists, materialized paths, nested sets and closure tables compared, and why a parent_id column plus a recursive CTE is the right default.
#data-modeling#schema-design
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
GeneralIntermediateSelect-then-insert breaks under concurrency. Use a unique constraint plus one atomic statement: ON CONFLICT, ON DUPLICATE KEY UPDATE, or UPDLOCK/SERIALIZABLE in SQL Server.
#concurrency#schema-design#transactions
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
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
MongoDBBeginnerThe core modeling decision in MongoDB, with simple rules of thumb for one-to-few, one-to-many and many-to-many relationships.
#data-modeling#nosql#schema-design
Apache CassandraIntermediateForget normalization. In Cassandra you model one table per query, choose partition keys carefully and keep partitions bounded.
#data-modeling#nosql#schema-design
