The Phantom Read Debugging Lab

The Phantom ReadDatabases & ConsistencyMediumPreparing workspaceAutosaved

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Incident Dossier

The Phantom Read

A staged write is invisible to the very transaction that staged it. The customer adds ten units of stock, queries the on-hand count, and sees zero.

Initial failing signalread inside a tx cannot see its own pending writeExpected stock == 10 · received stock == 0

Progress

1Reproduce the bugRun checks

2Edit the fixOpen

3Pass checksOpen

4Submit fixOpen

Reproduction Steps

Focus Mode

Start

Likely area

Progressive hints

Hints reveal broad direction first, then narrow toward the suspect path without showing hidden tests or exact solution code.

TopicDatabases & Consistency

DifficultyMedium

Est. time18 min

Workspacecreating

Explorer

Preparing workspace files…

Evidence Map

Autosaved

workspace

Outputread-onlyready$ workspace boot

Workspace booting...