Unable to resume backup

[jareware]

# couchbackup --version
2.2.0
# node -v
v8.2.1

First backup:

================================================================================
Performing backup on https://****:****@my-db.example.com/ca9d8d9c-d2e0-47b9-99e4-1d2d0f2ba344 using configuration:
{
  "bufferSize": 1000,
  "log": "ca9d8d9c-d2e0-47b9-99e4-1d2d0f2ba344.log",
  "mode": "full",
  "parallelism": 1
}
================================================================================
  couchbackup:backup Fetching all database changes... +0ms
  couchbackup:backup Total batches received: 1 +527ms
  couchbackup:backup Total batches received: 2 +88ms
  couchbackup:backup Total batches received: 3 +90ms
  couchbackup:backup Written batch ID: 0 Total document revisions written: 1000 Time: 2.346 +2s
  couchbackup:backup Written batch ID: 1 Total document revisions written: 2000 Time: 3.846 +1s
  couchbackup:backup Written batch ID: 2 Total document revisions written: 2984 Time: 5.295 +1s
  couchbackup:backup Finished - Total document revisions written: 2984 +11ms

Check to see the remote doc count:

# curl -s 'https://****:****@my-db.example.com/ca9d8d9c-d2e0-47b9-99e4-1d2d0f2ba344' | node -p 'JSON.parse(fs.readFileSync(0))' | grep doc_count
  doc_count: 2986,

Wait a while, run again:

# curl -s 'https://****:****@my-db.example.com/ca9d8d9c-d2e0-47b9-99e4-1d2d0f2ba344' | node -p 'JSON.parse(fs.readFileSync(0))' | grep doc_count
  doc_count: 2991,

OK, the remote DB has definitely changed; back up again:

================================================================================
Performing backup on https://****:****@my-db.example.com/ca9d8d9c-d2e0-47b9-99e4-1d2d0f2ba344 using configuration:
{
  "bufferSize": 1000,
  "log": "ca9d8d9c-d2e0-47b9-99e4-1d2d0f2ba344.log",
  "mode": "full",
  "parallelism": 1,
  "resume": true
}
================================================================================
  couchbackup:backup Fetching all database changes... +0ms
  couchbackup:backup Finished - Total document revisions written: 0 +339ms

Nothing got written, and the backup files (txt & log) haven't changed.

Is this a bug, or am I just misunderstanding how the --resume option works?

[ricellis]

I'm afraid you're misunderstanding how the --resume option works.

The --resume option works for a backup that has finished spooling changes, but has not yet completed downloading all the necessary batches of documents.

I can see from your output above that your first backup has:

couchbackup:backup Finished - Total document revisions written: 2984 +11ms

So the resume in your second backup command has no effect because the backup has already completed.

What you are looking for is incremental backup, which is not available at this time. It is tracked in #11 (which I see you found and commented on). Seems like our documentation could use some improvement in this area.

[jareware]

Ah, good to know! And good that I checked before leaving the script running, thinking I'm always backed up. :>

Do you want a small PR for the docs change?

[smithsz]

Thanks @jareware. I'll update the docs for this.