Yingwen
6a40c0b811
* docs(mito): specify columnar samples format Signed-off-by: evenyag <realevenyag@gmail.com> * feat(mito): implement columnar samples format Signed-off-by: evenyag <realevenyag@gmail.com> * fix(mito): address columnar samples review feedback Signed-off-by: evenyag <realevenyag@gmail.com> * style(mito): use crate-rooted samples imports Signed-off-by: evenyag <realevenyag@gmail.com> --------- Signed-off-by: evenyag <realevenyag@gmail.com>
1.9 KiB
Mito columnar samples version 1
This fixture freezes the version-1 sample wire contract in
mito-samples.md. It is exercised by
the owning Mito Rust test, not SQLness discovery:
cargo nextest run -p mito2 frozen_v1_samples_fixture_and_unknown_codec
v1-manifest.json and v1-part.hex describe a 397-byte part with raw compression,
one leaf/root, and two samples for (table_id=7, tsid=42) at timestamp 100 ms.
The first row is a put with sequence 9 and Float64 negative zero. The second is a
delete with sequence 8 and a null field. Both rows must survive decoding.
The part was assembled independently of the Rust writer, using explicit little-endian fields and XXH64 with seed zero. Its layout is:
| Range | Content |
|---|---|
| 0..16 | Header |
| 16..32 | Constant-step timestamps: first 100, step 0 |
| 32..41 | Delta sequences: first 9, ZigZag delta -1 |
| 41..43 | Raw operations: put 1, delete 0 |
| 43..53 | Nullable XOR: bitmap mode, validity 0x01, negative-zero bits |
| 53..285 | Leaf/root: one block, four column references |
| 285..397 | Trailer with root reference and checksum |
The test installs these exact bytes and recorded object sizes, opens them through
SamplesFormat, and verifies the values and order. It also changes a column
codec to an unknown ID while updating checksums to test that unrequested columns
can be skipped and requested unknown codecs fail explicitly. Legacy catalog
identifier coverage remains in series_index::catalog tests.
Do not regenerate this fixture just to make a reader change pass. Preserve its
bytes for future reader compatibility; introduce a separate versioned fixture
when the approved format changes. This is a frozen-byte compatibility check,
not a cross-binary upgrade/downgrade test. Older binaries are not promised to
understand the new opt-in columnar-samples catalog identifier.