Publish metrics with explicit units and denominators
Calculate a combined request-quality SLI in SQLite, distinguish conditional denominators and fast errors, and bound the result when duration measurements are missing.
Foundation
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A little theory. A lot of practice.
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
Reconcile source and target totals after a load
Compare scoped row counts, reported-value counts, quantities and identities to expose balanced errors, null changes and shared omissions.
Foundation
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
Declare the grain of an analytical table
Define what one analytical row represents, keep receipt and line measures separate, and distinguish a missing line from an observed zero with executable SQL.
Foundation
A join table that cannot contain duplicate memberships
Protect tenant-scoped membership identity, preserve roles during repeated adds, and reproduce an insert-or-fetch query that returns nothing after a conflict.
Foundation
Use primary keys and foreign keys to preserve an order
Model order identity, reject orphan references, inspect cascades and separate database relationships from the policy for deleting a paid order.
Foundation