seaweedfs/weed/filer/arangodb

##arangodb

database: https://github.com/arangodb/arangodb go driver: https://github.com/arangodb/go-driver

options:

[arangodb]
enabled=true
db_name="seaweedfs"
servers=["http://localhost:8529"]
#basic auth
user="root"
pass="test"

# tls settings
insecure_skip_verify=true

i test using this dev database: docker run -p 8529:8529 -e ARANGO_ROOT_PASSWORD=test arangodb/arangodb:3.9.0

database structure

arangodb has a few restrictions which require the use of a few tricks in order to losslessly store the data.

filer store

arangodb does not support []byte, and will store such as a uint64 array. this would be a waste of space. to counteract this, we store the data as a length prefixed uint64 byteset.

filer kv

same as above

filer buckets

s3 buckets are implemented through arangodb collection. this allows us to do very fast bucket deletion by simply deleting the collection

arangodb collection name rules is character set azAZ09_- with a 256 character max. however the first character must be a letter.

s3 bucket name rule is the set azAZ09.- with a 63 characters max.

the rules for collection names is then the following:

1. if the bucket name is a valid arangodb collection name, then nothing is done.
2. if the bucket name contains a ".", the "." is replaced with "_"
3. if the bucket name now begins with a number or "_", the prefix "xN--" is prepended to the collection name

this allows for these collection names to be used.

features i don't personally need but are missing

[ ] provide tls cert to arango [ ] authentication that is not basic auth [ ] synchronise endpoint interval config [ ] automatic creation of custom index [ ] configure default arangodb collection sharding rules [ ] configure default arangodb collection replication rules

complexity

ok, so if https://www.arangodb.com/docs/stable/indexing-index-basics.html#persistent-index is correct

O(1)

• InsertEntry
• UpdateEntry
• FindEntry
• DeleteEntry
• KvPut
• KvGet
• KvDelete

O(log(BUCKET_SIZE))

• DeleteFolderChildren

O(log(DIRECTORY_SIZE))

• ListDirectoryEntries
• ListDirectoryPrefixedEntries