Writes The Cache Missed

A team runs a write-through cache in front of an inventory table and treats the cached copy as always matching the database. A nightly batch job and an on-call repair script both update rows with direct SQL. What does that do to the assumption?

The affected entries are dropped, because the database refuses to commit a row that a cache still has open

Write-through covers only writes that pass through the cache, so direct SQL updates leave cached copies stale

Nothing changes, because a write-through cache validates each entry against the row before it serves a read

Nothing changes, because a write-through cache consumes the database's change stream and applies those edits too