Prevent lost updates with a conditional UPDATE
Protect concurrent profile edits with a version-checked SQL update, distinguish zero rows from errors, and test conflict resolution and unversioned writers.
Foundation
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Engineering & everyday learningNotes from
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Software, systems, and the things I’m learning along the way. From first principles to AI in production.
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A little theory. A lot of practice.
A transaction for moving credits between accounts
Transfer credits with PostgreSQL, check affected rows, observe commit from two sessions, and reproduce rollback, insufficient funds and repeated-request limits.
Foundation
Read Committed and the changing result of a second SELECT
Trace changing inventory reads in PostgreSQL Read Committed, compare Repeatable Read, and locate snapshot boundaries at the first query and statement start.
Foundation