175 articles · 35 databases · 63 topics
Practical tutorials, performance tuning and internals for SQL Server, PostgreSQL, MySQL, MongoDB, Redis and every engine in between — written by people who run them in production.
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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.
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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
Learning paths
LEVEL 01
Tables, keys, joins and your first indexes. Build intuition that lasts.
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LEVEL 02
Query plans, transactions, replication and schema design trade-offs.
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LEVEL 03
Storage engines, concurrency control, internals and extreme tuning.
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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 ServerIntermediateExecution plans tell you exactly how SQL Server ran your query. Learn which operators matter, how to spot bad estimates and what the warnings really mean.
#execution-plans#performance#t-sql
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
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
