Topic
SQL ServerBeginnerA 200 GB .ldf for a 20 GB database? Shrinking only treats the symptom. log_reuse_wait_desc tells you the real cause, and here's how to fix each one.
#maintenance#transactions#troubleshooting
Raising max_connections to 1000 usually makes things worse. Learn why Postgres connections are expensive, where they're leaking and how PgBouncer fixes it for good.
#configuration#performance#troubleshooting
SQLiteIntermediateAn ordered procedure for SQLITE_BUSY with a verification for each step, a script that reproduces the contention, and the matching settings for Python, Node and Go drivers.
#concurrency#locking#troubleshooting
SQLiteIntermediateWhat SQLITE_BUSY means, where it is returned in rollback-journal and WAL mode, why a timeout sometimes does nothing, the extended codes, and how to find who holds the lock.
#concurrency#internals#locking
SQL ServerIntermediateSame proc, same code, suddenly 100× slower, and fast again when you run it in SSMS. Here's how parameter sniffing causes it, how to prove it and the fixes that actually hold.
#execution-plans#performance#troubleshooting
ElasticsearchIntermediateYellow means missing replicas and red means missing primaries. Use the allocation explain API to find the exact cause: replica count, disk watermarks, allocation filters or failed retries.
#configuration#nosql#troubleshooting
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
MySQLIntermediateStale reads and 2 a.m. lag spikes usually come down to single-threaded apply, tables without primary keys and giant transactions. Diagnose and fix each one.
#performance#replication#troubleshooting
SQLiteBeginnerStill getting SQLITE_BUSY with a timeout set? The default timeout is zero and deferred transactions can't wait. WAL mode, busy_timeout and BEGIN IMMEDIATE fix most cases.
#concurrency#locking#troubleshooting
GeneralBeginnerThe N+1 query problem: each query takes 1 ms, but there are 301 of them. How to spot it, fix it with eager loading and avoid the cartesian-explosion overcorrection.
#orm#performance#troubleshooting
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
