Green-Sky/solanaceae_object_store
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add file2 experimentally to the backend interface
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README.md

Object Store

Objects are are pieces of information split into Metadata and Data. They can be stored seperated or together. They can be used as a Transport protocol/logic too.

see wikipedia

Store types

Filesystem Store

Fragment files are stored with the first 2 hex chars as sub folders: eg: objects/ (object store root)

  • 5f/ (first 2hex subfolder)
    • 4fffffff (the fragment file without the first 2 hexchars)

Metadata and data stored in seperate files. Metadata files have the .meta suffix. They also have a filetype specific suffix, like .json, .msgpack etc. (single file objects are planned but no ETA)

Memory Store

Just keeps the Fragments in memory.

File formats

Files can be compressed and encrypted. Since compression needs the data's structure to work properly, it is applied before it is encrypted.

Text Json

Text json only makes sense for metadata if it's neither compressed nor encrypted. (otherwise its binary on disk anyway, so why waste bytes). Since the content of data is not looked at, nothing stops you from using text json and ecrypt it, but atleast basic compression is advised.

A Metadata json object can have arbitrary keys, some are predefined:

  • FragComp::DataEncryptionType (uint) Encryption type of the data, if any
  • FragComp::DataCompressionType (uint) Compression type of the data, if any

Binary msgpack

msgpack array:

  • [0]: file magic string SOLMET (6 bytes)
  • [1]: uint8 encryption type (0x00 is none)
  • [2]: uint8 compression type (0x00 is none, 0x01 is zstd)
  • [3]: binary metadata (optionally compressed and encrypted)

note that the encryption and compression are for the metadata only. The metadata itself contains encryption and compression info about the data.

Split Data

All the metadata is in the metadata file. (like encryption and compression) This is mostly to allow direct storage for files in the Fragment store without excessive duplication. Keep in mind to not use the actual file name as the data/meta file name.

Compression types

  • 0x00 none
  • 0x01 zstd (without dict)

zstd with hardcoded dictionaries will come later.