f0:int b0:blob b1:blob b2:blob b3:blob (all can be null)
bucket count: -1
target-file-size: 700
row-tracking.enabled: true
data-evolution.enabled: true
blob-descriptor-field: b0,b1

b0: descriptor field, inline in main file, source .bin files in raw_blob/
b1: descriptor field whose descriptor points to external_blob/
b2: regular blob, written to .blob files
b3: regular blob, written to .blob files

Note: this fixture keeps historical descriptor URIs pointing at raw_blob/ and external_blob/.

Msgs:
snapshot-1
write field: "f0", "b0", "b1", "b2", "b3"
Add: 1, "img_0", null,    "raw_2_0", "raw_3_0"
Add: 2, "img_1", "vid_1", "raw_2_1", null
Add: 3, "img_2", null,    "raw_2_2", "raw_3_2"
NoCompact

C++ read note:
  Descriptor URIs contain absolute paths from the Java generation machine.
  ConvertDescriptorToRawBlob uses BlobDescriptorPathRewrite{"raw_blob", "external_blob"}
  to redirect them to <table>/raw_blob/ and <table>/external_blob/ at read time.
