etch
Kiểm tra và bảo trì một cửa hàng Etch — cơ sở dữ liệu định địa chỉ theo nội dung của Convex. Sử dụng khi kiểm tra bộ nhớ ngang hàng, chẩn đoán hỏng hóc, thu gom rác, hoặc…
npx skills add https://github.com/convex-dev/convex --skill etchEtch Store Operations
Etch is Convex's content-addressed store: values are keyed by hash, and a single root hash reaches everything retained. Peers keep their state here.
Every subcommand takes the store file with -e / --etch:
java -jar convex.jar etch info -e /path/to/store.etch
Inspecting
| Command | Purpose |
|---|---|
etch info | Summary of the database — start here |
etch validate | Check store integrity; -m/--max-failures N to bound reporting |
etch dump | Export contents, CSV by default (value ID, type, memory size, encoding) |
etch read <hash>... | Read specific values by hash; --limit N to cap output |
info, dump and read take -o / --output-file to write to a file rather
than the terminal — use it for dump on any real store, which is large.
Start a diagnosis with info, then validate. If validation reports failures,
capture the output before doing anything that mutates the store.
Maintenance
These modify or destroy data. Confirm with the user, and make sure the peer using the store is stopped first — operating on a live store risks corruption.
| Command | Effect |
|---|---|
etch gc | Garbage collect the root tree. In-place by default; --backup <file> also retains the old store as a snapshot; -o/--output <file> collects into a fresh file instead |
etch clear | Clears the root data. Does not collect garbage |
etch migrate --into <dest> | Copy everything into another store; --set-root to set the destination root |
etch repair --into <dest> | Reconstruct a fresh store from independently validated cells; source unchanged |
etch recover | Adopt a completed GC cutover or roll an abandoned target back into the live store |
etch write -c/--cvx <source> | Write a CVM value into the store |
To compact safely, prefer gc -o <new-file>: it collects into a fresh file and
leaves the source unmodified (note: status levels above PERSISTED, e.g.
ANNOUNCED, survive an in-place GC but not --output). Use migrate to copy
into another (possibly non-empty) store, or to change the store's format
version or encryption — see below.
For a combined snapshot and in-place collection, use
gc --backup <snapshot-file>. The collected store keeps the original live path;
the backup retains the pre-GC root and all old entries, including unreachable
data. It uses a hard link, so the backup must have a new filename on the same
filesystem with hard-link support. Existing backups are never overwritten.
The old disk space remains allocated until the snapshot is removed. Treat the
snapshot as read-only and use a separate copy for a backup on another filesystem.
--backup and --output are mutually exclusive. A backup left by an interrupted
command is not a confirmed snapshot; inspect the recovery state first.
On Windows use the same NTFS volume. Live writes after cutover use the collected
file, so they do not update the snapshot. The FFM backend releases mappings on
close; MappedByteBuffer mappings may defer installation at the live filename.
Etch follows its completion marker until a later open can finish installation.
repair is the offline salvage path for a dirty or damaged source. It holds an
exclusive source lock, scans through physical EOF, and writes only canonical
CAD3 values whose stored content hashes verify. A complete result requires both
a fully persisted selected root and an exhaustive scan. If either condition
fails, the command reports failure but may leave a valid partial destination;
never replace the source with that output automatically.
Recovering an interrupted GC is what recover is for — reach for it before
concluding a store is lost.
Encrypted Stores (Etch v3)
Etch format v3 supports encrypted stores — format spec in
convex-core/docs/ETCHv3.md.
Opening an encrypted store: any etch subcommand takes --etch-key <alias>
(keystore key alias or public-key prefix, password via --etch-keypass) or
--etch-key-file <file> (raw or hex 32-byte master key; - reads stdin).
With neither, the v3 header's public-key hint selects a keystore key
automatically, or an interactive session prompts for a hex key.
Converting a store: etch migrate (and gc -o) accept destination
options — --into-version (1, 2 or 3), --into-cipher (none,
aes-256-ctr or chacha20), --into-key / --into-key-file /
--into-keypass for the destination key, --into-encrypt-index (negatable)
and --into-public-key-hint. Encryption options require version 3; without a
destination key the resolved source key is reused.