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Q&A
Q&AA primary key gives each row a stable identity; it does not replace domain-level uniqueness constraints.
A primary key lets the database and applications refer to one row unambiguously and lets foreign keys express relationships. Add separate unique constraints for business rules such as one account per email. A generated ID alone does not prevent duplicate domain entities.
Q&A
Q&AType assertions are erased. Treat untrusted data as unknown and validate its shape and domain constraints before relying on it.
Type assertions are erased. Treat untrusted data as unknown and validate its shape and domain constraints before relying on it.
databases
10 minLearn tables, keys, constraints, joins, transactions, and query shape before choosing a specific database engine.
databases
9 minCompare database routines and triggers with application services, focusing on transaction ownership, portability, and operational visibility.
kubernetes
6 minUnderstand eviction admission, readiness accounting, and why a drain can correctly refuse to proceed.
devops
8 minReason about OIDC trust, token audience, job identity, and short-lived cloud credentials.
Q&A
Q&ATwo transactions can read the same invariant and update disjoint rows, so row-level conflicts do not detect the violation.
If each transaction sees a snapshot where another row satisfies a rule, they may update different rows and both commit, leaving the combined invariant false. Use a constraint, lock a shared coordination row, or use serializable isolation with whole-transaction retry. Exact Repeatable Read semantics differ by engine.
security
5 minEnforce access on individual resources, keep data separate from executable structure, and prevent sensitive values from crossing logging and build boundaries.