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databases/the-n-1-query-problem-why-a-page-that-asks-the-database-501-questions.md The N+1 query problem: why a page that asks the database 501 questions is slow A page that lists authors and their books can quietly send one query per author. With 500 authors that is 501 trips to the database, and… 4 min read · 26 Oct mobile/list-recycling-why-a-phone-can-scroll-10-000-contacts-while-building-o.md List recycling: why a phone can scroll 10,000 contacts while building only 8 rows A phone can scroll through 10,000 contacts without building 10,000 rows. It builds only enough row views to cover the screen, then recycles… 5 min read · 25 Oct databases/sql-indexes-why-finding-one-row-among-200-000-takes-about-18-steps.md SQL indexes: why finding one row among 200,000 takes about 18 steps A database with 200,000 customers can answer "find this email" by reading every row, or by reading about 18 entries. The difference is an… 4 min read · 20 Oct computer-science/big-o-how-to-tell-if-your-code-will-survive-1-000-times-more-data.md Big O: how to tell if your code will survive 1,000 times more data Your code works on 10 items, then crawls on 10,000. Big O is the short way programmers describe how the number of steps grows as the input… 4 min read · 11 Oct computers/cpu-cache-why-reading-a-grid-by-rows-beats-columns-step-by-step.md CPU cache: why reading a grid by rows beats columns, step by step Two loops add up the same grid of numbers, yet one can run about ten times slower. The reason is a small, fast memory inside your processor… 5 min read · 7 Oct databases/what-is-a-database-index-find-one-row-without-reading-them-all.md What is a database index? Find one row without reading them all Ask a database for one person among a million rows and it could read every row until it finds them. That is slow. An index is the… 5 min read · 4 Oct