SQL Fundamentals
Why Your Benchmark Measured the Cache
A query run five times in a row reports the speed of memory, not of the system. Which layer answered the request is the first thing to establish.
· 3 min
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SQL Fundamentals
The language itself: set theory, joins, window functions, CTEs and the mental models behind them.
3 articles
SQL Fundamentals
Composite Indexes: One Ordering, Not Three
Column order decides which queries a composite index can serve. The rule follows from the structure, and so do the cases where it does not hold.
· 3 min
SQL Fundamentals
N+1 Queries: What the ORM Is Actually Doing
One query for the list, then one more for every item in it. The cost is per statement, which is why the profiler shows a fast database and a slow request.
· 3 min