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Architecture Case Studies — Series 2
Preview — 3 of 10 questions
A ride-matching service receives driver locations every few seconds. A driver's connection disappears. What prevents matching against indefinitely stale coordinates?
AUse server receipt time alone even for delayed replayed location batches.
BKeep the last point forever because spatial indexes guarantee freshness.
CUse a more precise geohash while ignoring observation time.
DTrack observation age and expire or exclude stale availability records.
A file is divided into fixed-size chunks. Bytes are inserted near the beginning. Why might more than one chunk need uploading?
AChunk deduplication removes the need to compare actual content.
BEvery chunk hash stays constant whenever total file size increases.
CFixed-size chunking guarantees only the first chunk changes.
DThe insertion shifts later boundaries and changes many chunk contents.
A payment system uses double-entry records. Which invariant should a committed journal transaction enforce in one currency?
AEvery payment creates exactly one row regardless of its postings.
BA network retry always creates a new independent journal transaction.
CTotal debits equal total credits for that journal transaction.
DEvery account balance is positive after every transaction.
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