Data and storageRow versions
Why does your database keep the old balance after you change it?
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More questions.
Networking and APIsRound trips
Ten calls from a phone, or one. Why is one about 9× faster?
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Data and storageDeadlocks
Asha pays Bilal as Bilal pays Asha. Why do both transfers get stuck?
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Networking and APIsThe N+1 trap
Your GraphQL screen lists 20 orders. Why did it make 21 calls?
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Data and storagePage LSNs
Why can crash recovery itself crash, then simply start again?
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Networking and APIsRouting
Asha and Ravi sit on different servers. How does her message find him?
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Data and storageAutovacuum
Why does autovacuum let 100 million dead rows pile up on a big table?
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Networking and APIsRetries
Your server was down all weekend. Are those orders gone for good?
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Data and storageWrite cost
Why do four extra indexes triple an insert’s page writes?
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Networking and APIsOpaque tokens
Your page token looks like gibberish. So why can anyone read it?
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Data and storageLeftmost prefix
Why can a train chart find coach S4 instantly, but not Mr Iyer?
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Networking and APIsThe 2⁵³ trap
Your server sent order 1234567890123456789. Why did JavaScript read a different order?
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Data and storageRandom reads
Why can reading all 16 pages beat reading only the 5 you need?
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Networking and APIsUploads
Users post photos. Why shouldn’t the bytes go through your API?
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Data and storageEXPLAIN ANALYZE
Why can running EXPLAIN ANALYZE cancel real orders?
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Networking and APIsPartial failure
Reviews timed out. Should the whole product page fail?
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Data and storageCartesian explosion
Why would joining two tables return 60,000 rows for 50 cards?
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Networking and APIsCaching
How can a CDN show one user another user’s profile?
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Data and storageShifting rows
Why did the same order show up twice in your infinite scroll?
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Networking and APIsTimeouts
The gateway said 504, yet the payment went through. How?
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Data and storagePool size
The database is at 100% CPU. Should you add connections?
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Networking and APIsAcross services
Checkout calls Payments, then retries. Who stops the second charge?
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Data and storagePruning
How does a query skip 11 of 13 partitions without touching an index?
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Networking and APIsConcurrency
The database slowed down, but your rate limit never fired. Why?
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Data and storageLogical shards
Why did Notion split its data into 480 shards, not a neat 512?
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Data and storageFailover
How did a 43-second network cut leave GitHub degraded for 24 hours?
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