frostfs-node/pkg/local_object_storage/metabase/VERSION.md

Metabase versioning

This file describes changes between the metabase versions.

Warning: database schema below is outdated and incomplete, see source code.

Current

Primary buckets

• Graveyard bucket
  • Name: _Graveyard
  • Key: object address
  • Value: tombstone address
• Garbage bucket
  • Name: _Garbage
  • Key: object address
  • Value: dummy value
• Bucket containing IDs of objects that are candidates for moving to another shard.
  • Name: _ToMoveIt
  • Key: object address
  • Value: dummy value
• Container volume bucket
  • Name: _ContainerSize
  • Key: container ID
  • Value: container size in bytes as little-endian uint64
• Bucket for storing locked objects information
  • Name: _Locked
  • Key: container ID
  • Value: bucket mapping objects locked to the list of corresponding LOCK objects
• Bucket containing auxilliary information. All keys are custom and are not connected to the container
  • Name: _i
  • Keys and values
    • id -> shard id as bytes
    • version -> metabase version as little-endian uint64
    • phy_counter -> shard's physical object counter as little-endian uint64
    • logic_counter -> shard's logical object counter as little-endian uint64

Unique index buckets

• Buckets containing objects of REGULAR type
  • Name: container ID
  • Key: object ID
  • Value: marshalled object
• Buckets containing objects of LOCK type
  • Name: container ID + _LOCKER
  • Key: object ID
  • Value: marshalled object
• Buckets containing objects of STORAGEGROUP type
  • Name: container ID + _SG
  • Key: object ID
  • Value: marshaled object
• Buckets containing objects of TOMBSTONE type
  • Name: container ID + _TS
  • Key: object ID
  • Value: marshaled object
• Buckets mapping objects to the storage ID they are stored in
  • Name: container ID + _small
  • Key: object ID
  • Value: storage ID
• Buckets for mapping parent object to the split info
  • Name: container ID + _root
  • Key: object ID
  • Value: split info

FKBT index buckets

• Buckets mapping owner to object IDs
  • Name: containerID + _ownerid
  • Key: owner ID as base58 string
  • Value: bucket containing object IDs as keys
• Buckets containing objects attributes indexes
  • Name: containerID + _attr_ + attribute key
  • Key: attribute value
  • Value: bucket containing object IDs as keys

List index buckets

• Buckets mapping payload hash to a list of object IDs
  • Name: container ID + _payloadhash
  • Key: payload hash
  • Value: list of object IDs
• Buckets mapping parent ID to a list of children IDs
  • Name: container ID + _parent
  • Key: parent ID
  • Value: list of children object IDs
• Buckets mapping split ID to a list of object IDs
  • Name: container ID + _splitid
  • Key: split ID
  • Value: list of object IDs

History

Version 3

• Payload hash, owner ID and FKBT buckets deleted
• Expiration epoch to object ID and object ID to expiration epoch added

Version 2

• Container ID is encoded as 32-byte slice
• Object ID is encoded as 32-byte slice
• Object ID is encoded as 64-byte slice, container ID + object ID
• Bucket naming scheme is changed:
  • container ID + suffix -> 1-byte prefix + container ID

Version 1

• Metabase now stores generic storage id instead of blobovnicza ID.

Version 0

• Container ID is encoded as base58 string
• Object ID is encoded as base58 string
• Address is encoded as container ID + "/" + object ID