Taking the weekly preview from the writer dropped the schema check the
old scanner ran at the end, so a copy that violates the schema was
described as restorable. The collector now checks each section in its
JSON form as the writer shows it, an array section and a bulk table one
element at a time, plus the schema's one whole-document rule (a
canonical copy names every measurement by id). A copy that fails gets
no stored preview, and the preview route reads the copy itself, as it
did before. Nothing is kept beyond one element.
Measured on the preview memory test under --max-old-space-size=524:
held after the producer 3 MB with and without the check, raw peak
heapUsed 293 MB with it (335 MB without). The test now loads the
backup schema before its baseline: a module loaded once per process,
not memory that grows with the record.
Since v1.39.6 the preview scanner parsed the JSON on its way into the
pieces, kept every section but the three bulk tables, and validated the
whole document at the end: a second copy of the record beside the
writer's own, inside the weekly job. On an account with a document vault
that is most of the record.
The writer now shows each section and each bulk row to an observer just
before writing it. The preview collects key uses from that and takes its
counts from the writer's own FullBackupCounts; nothing is parsed or kept.
An upload hands over the summary and key uses it has already validated.
The round trip pins the writer's counts and key uses to a full read of
the copy on an account with a row in every model, and a memory test holds
what the pass keeps once the producer is done.
Measured on 70,000 measurements, 3,000 mood entries and 40 one-megabyte
documents under --max-old-space-size=524: held after the producer
56 MB before, 3 MB after; peak heapUsed 398 MB before, 334 MB after.
Marc-André Bombeck