mongodb dropped collection keeps coming back after mongodump and mongorestore - mongodb

Question

I have just created a data set, but a collection, 'items', is still lurking around and I am getting rid of it with the command db.items.drop() (after exec'ing into my docker container), which seems to successfully remove it. But when I run the 2 following scripts (after removing the collection):
save script:
#!/usr/bin/env bash
MONGO_DB_NAME="test-1"
DATA_NAME="test-data"
docker exec ${MONGO_DB_NAME} mongodump --quiet --out /tmp/${DATA_NAME}
mkdir -p ./backup
docker cp ${MONGO_DB_NAME}:/tmp/${DATA_NAME} ./backup/${DATA_NAME}
docker exec ${MONGO_DB_NAME} rm -rf /tmp/${DATA_NAME}
restore script:
#!/usr/bin/env bash
MONGO_DB_NAME="test-1"
DB_NAME="docker-node-mongo"
DATA_NAME="test-data"
docker exec -it $(docker ps -aqf "name=${MONGO_DB_NAME}") mongo ${DB_NAME} --eval "db.dropDatabase();"
docker cp ./backup/$DATA_NAME $(docker ps -aqf "name=${MONGO_DB_NAME}"):/tmp
docker exec -it $(docker ps -aqf "name=${MONGO_DB_NAME}") mongorestore --drop /tmp/${DATA_NAME}
the items collection comes right back. Does anyone know why this is? I'd like it gone for good.
Edit: When I delete individual items from the collection, and run the above scripts, they do not come back. But when I drop the collection as a whole, the collection keeps coming back (with nothing in it).

Answer 1

The mongodump command does not delete files that already exist in the --out path. Files for collections that are being backed up will be overwritten, but files for collection that no longer exist will not be touched, leaving the 'items' file(s) there to be restore the next time you run mongorestore.
To make sure this doesn't happen, move aside or remove the existing backup directory and create a new, empty one before running mongodump.

Answer 2

I had exactly similar "haunting" collection, which kept coming back again and again. The haunting collection also didn't work ok (e.g. cloning within it caused always an error). I don't know what caused it, but from some console logs I finally noticed that somehow another collection was using it's Name. I was then able to fix it by renaming the collection via mongosh and deleting then:
db.rrecord.renameCollection("record")
"This operation will rename the rrecord collection to record. If the target name (i.e. record) is the name of an existing collection, then the operation will fail."
ref. https://docs.mongodb.com/manual/reference/method/db.collection.renameCollection/