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* docs: design for syncing updated book data (cover + file) (#4544) Cover-change sync via a content hash (coverHash = partial MD5 of cover.png) plus a cover_updated_at field-level merge timestamp; file updates ride the existing re-import / metaHash dedupe. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> * fix(sync): sync updated book covers across devices (#4544) Editing a book's cover wrote cover.png locally but changed no hash (the cover is keyed by the file hash), so peers had no signal to re-download it and the change never propagated. Give the cover its own content-addressed version: - coverHash = partial MD5 of cover.png; a peer re-downloads the cover iff the synced hash differs from the local one (idempotent, no churn on identical/re-extracted covers — compatible with the metaHash dedupe). - coverUpdatedAt = field-level LWW timestamp so a page-turn that wins whole-row LWW on updated_at can't clobber a cover edit (mirrors the reading_status_updated_at fix for #4634). Editing a cover recomputes the hash, bumps coverUpdatedAt, and re-uploads only the cover; the server merges cover fields independently; peers re-download on a hash diff. File updates continue to ride the existing re-import / metaHash dedupe (changed file -> changed hash -> re-key). Migration 016 adds cover_hash / cover_updated_at to books. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> --------- Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
23 lines
1.3 KiB
SQL
23 lines
1.3 KiB
SQL
-- Migration 017: Add `cover_hash` / `cover_updated_at` to books
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--
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-- Cover-change sync (issue #4544). Editing a book's cover writes cover.png
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-- locally but changes no hash (the cover is keyed by the file hash), so peers
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-- had no signal to re-download it. Give the cover its own content-addressed
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-- version:
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--
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-- cover_hash = partial MD5 of cover.png. A peer re-downloads the cover
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-- iff its synced cover_hash differs from the local one.
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-- Content-addressed ⇒ a byte-identical (re-extracted /
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-- re-imported) cover yields the same hash ⇒ no re-sync
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-- churn (compatible with the metaHash dedupe mechanism).
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-- cover_updated_at = field-level last-writer-wins timestamp so a page-turn
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-- that wins whole-row LWW on updated_at cannot clobber a
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-- cover edit — the same hazard the 015
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-- reading_status_updated_at fix addressed for #4634.
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--
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-- Both additive + nullable; NULL cover_updated_at is treated as epoch 0
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-- (oldest) by the merge. Old clients ignore the columns, so they never break.
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ALTER TABLE public.books
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ADD COLUMN IF NOT EXISTS cover_hash text NULL,
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ADD COLUMN IF NOT EXISTS cover_updated_at timestamp with time zone NULL;
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