Dump file format​

This description uses the same conventions as the protocol description.

The dump file format is not final and is subject to change before EdgeDB 1.0.

General Structure​

Dump file is structure as follows:

  1. Dump file format marker \xFF\xD8\x00\x00\xD8EDGEDB\x00DUMP\x00 (17 bytes)

  2. Format version number \x00\x00\x00\x00\x00\x00\x00\x01 (8 bytes)

  3. Header block

  4. Any number of data blocks

General Dump Block​

Both header and data blocks are formatted as follows:

  1. struct DumpHeader {
  2.     int8            mtype;
  4.     // SHA1 hash sum of block data
  5.     byte            sha1sum[20];
  7.     // Length of message contents in bytes,
  8.     // including self.
  9.     int32           message_length;
  11.     // Block data. Should be treated in opaque way by a client.
  12.     byte            data[message_length];
  13. }

Upon receiving a protocol dump data message, the dump client should:

  • Replace packet type:

    • @ (0x40) → H (0x48)

    • = (0x3d) → D (0x44)

  • Prepend SHA1 checksum to the block

  • Append the entire dump protocol message disregarding the first byte (the message type).

Header Block​

Format:

  1. struct DumpHeader {
  2.     // Message type ('H')
  3.     int8            mtype = 0x48;
  5.     // SHA1 hash sum of block data
  6.     byte            sha1sum[20];
  8.     // Length of message contents in bytes,
  9.     // including self.
  10.     int32           message_length;
  12.     // A set of message headers.
  13.     Headers         headers;
  15.     // Protocol version of the dump
  16.     int16           major_ver;
  17.     int16           minor_ver;
  19.     // Schema data
  20.     string          schema_ddl;
  22.     // Type identifiers
  23.     int32           num_types;
  24.     TypeInfo        types[num_types];
  26.     // Object descriptors
  27.     int32           num_descriptors;
  28.     ObjectDesc      descriptors[num_descriptors]
  29. };
  31. struct TypeInfo {
  32.     string          type_name;
  33.     string          type_class;
  34.     byte            type_id[16];
  35. }
  37. struct ObjectDesc {
  38.     byte            object_id[16];
  39.     bytes           description;
  41.     int16           num_dependencies;
  42.     byte            dependency_id[num_dependencies][16];
  43. }

Known headers:

  • 101 BLOCK_TYPE – block type, always “I”

  • 102 SERVER_TIME – server time when dump is started as a floating point unix timestamp stringified

  • 103 SERVER_VERSION – full version of server as string

Data Block​

Format:

  1. struct DumpBlock {
  2.     // Message type ('=')
  3.     int8            mtype = 0x3d;
  5.     // Length of message contents in bytes,
  6.     // including self.
  7.     int32           message_length;
  9.     // A set of message headers.
  10.     Headers         headers;
  11. }

Known headers:

  • 101 BLOCK_TYPE – block type, always “D”

  • 110 BLOCK_ID – block identifier (16 bytes of UUID)

  • 111 BLOCK_NUM – integer block index stringified

  • 112 BLOCK_DATA – the actual block data