databases
9 minStored Functions, Procedures, and Triggers: Put Logic in the Right Layer
Compare database routines and triggers with application services, focusing on transaction ownership, portability, and operational visibility.
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8 matching resultsArticles and interview answers
Q&A
Q&AWhy can a database trigger make an application write hard to debug?
The statement has side effects that are not visible at its call site.
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A trigger can modify other rows or tables implicitly during an insert or update. That makes the visible application statement an incomplete description of the transaction and can add locking or recursion. Document and test trigger effects, or move orchestration to an explicit routine/service when hidden behavior harms operability.
Q&A
Q&AWhat happens when a Kubernetes container reaches its CPU or memory limit?
CPU can be throttled; exceeding a memory limit can trigger an OOM kill.
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CPU usage above a configured limit is throttled, which can increase latency without stopping the process. Memory is not throttled in the same way: crossing the container limit can cause the kernel to kill the process, often reported as OOMKilled. Requests affect scheduling and utilization-based HPA calculations, so tune all values from observed workload behavior.
Q&A
Q&AWhy can grep make a shell script exit even though nothing is broken?
grep returns status 1 when there are no matches, which may trigger strict shell error handling.
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grep commonly exits 0 when it finds a match, 1 when it finds none, and 2 for an error. With `set -e`, an expected no-match status can terminate a script unless handled intentionally. Distinguish absence from malformed input or permission failures rather than suppressing every status.
Q&A
Q&AWhy can epoll handle many mostly-idle sockets more efficiently than select?
epoll tracks interest and reports readiness changes instead of requiring repeated full-set scans.
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select requires rebuilding and scanning descriptor sets on each wait and has platform-specific descriptor limits; poll also examines a supplied list. epoll maintains kernel-side interest and ready structures, which suits large mostly-idle sets. It does not remove per-connection memory costs, application scheduling, or edge-triggered drain requirements.
Q&A
Q&AHow do database functions differ from stored procedures?
Functions typically return values; procedures are invoked as operations, with engine-specific transaction rules.
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A function is commonly used as an expression or query result and returns a value or table. A procedure is invoked to perform an operation and may accept output parameters. Triggers run implicitly. Transaction control differs by engine, so keep commit ownership explicit and test routines against the target database/version.
Q&A
Q&AHow does CompletableFuture composition work, and what causes stalls?
Completion stages form a dependency graph; blocking the wrong executor can starve that graph.
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CompletableFuture represents a value that may complete later, with dependent stages triggered on completion. Async methods without an explicit executor commonly use a shared pool; blocking calls there can starve unrelated work. Prefer non-blocking composition, choose an executor suited to the task, set timeouts, and observe exceptional completion rather than calling join() throughout request paths.
devops
5 minIncident Timelines: Separate Event Time, Receipt Time, and Clock Evidence
Reconstruct a deployment incident without mistaking log delivery order or clock skew for causal ordering.