Topic
PostgreSQLIntermediateA session doing nothing can stop VACUUM from cleaning every table and stall your next migration. Find them, kill them safely and prevent them with the right timeouts.
#maintenance#mvcc#transactions
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
Oracle DatabaseIntermediateYour long query needed undo that was already overwritten. How Oracle read consistency uses undo, how to read V$UNDOSTAT, and why committing inside a loop causes it.
#configuration#mvcc#troubleshooting
PostgreSQLIntermediateMVCC means Postgres doesn't store a row count. Make exact counts cheaper, get instant estimates from the planner, and keep exact counters when you really need them.
#internals#mvcc#performance
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
