FWOB

FWOB is a Rust implementation of the Fixed-Width Ordered Binary format family.

The project provides two format versions:

FWOB v1 for compact fixed-width ordered files.
FWOB v2, a fixed-page compressed format for high-performance random access, range queries, and bulk append workloads.

FWOB v2 keeps page addresses arithmetic while allowing each page to contain a variable number of fixed-width frames. A page is a fixed-size on-disk container with an 80-byte header, compressed payload, and zero padding.

Workspace

fwob-core: shared schema, frame, key, reader/writer handles, service traits, and error types.
fwob-derive: derive macro for strongly typed fixed-width frames.
fwob-v1: FWOB v1 reader, writer, verifier, and compatibility tests.
fwob-v2: compressed fixed-page FWOB v2 reader and writer.
fwob: the primary library facade with auto-detecting Reader, Writer, Editor, Maintenance, and Organizer APIs, plus the command-line tool.

The logical Rust API is documented in docs/api.md. Repair can promote complete ordered frames or pages left beyond the committed count by an interrupted write, while truncating partial or invalid tails.

Installation

Install the command-line tool from crates.io:

cargo install fwob

Library crates are available separately as fwob, fwob-core, fwob-derive, fwob-v1, and fwob-v2.

Library Quick Start

use fwob::{Reader, Writer};
use fwob_core::{Field, FieldType, Schema};

let schema = Schema::new(
    "Tick",
    vec![Field::new("time", FieldType::SignedInteger, 8, 0)],
    0,
)?;

let mut writer = Writer::create_v2(
    "ticks.fwob",
    schema,
    fwob_v2::WriterOptions::new("prices"),
)?;
writer.append_frame(&123_i64.to_le_bytes())?;
writer.finish()?;

let mut reader = Reader::open("ticks.fwob")?;
let first = reader.first_frame()?.expect("one frame");
assert_eq!(first.bytes(), 123_i64.to_le_bytes());
# Ok::<(), Box<dyn std::error::Error>>(())

See docs/api.md for reading, appending, editing, maintenance, organization, typed-frame, and format-specific examples.

Typed frames map ordinary Rust structs directly to the stored schema:

use fwob::{TypedEditor, TypedReader, TypedWriter};
use fwob_core::FwobFrame;

#[derive(Debug, PartialEq, FwobFrame)]
struct Tick {
    #[fwob(key)]
    time: i64,
    price: u32,
    size: i32,
}

let mut writer = TypedWriter::<Tick>::create_v2(
    "ticks.fwob",
    fwob_v2::WriterOptions::new("prices"),
)?;
writer.append(&Tick { time: 1, price: 500, size: 10 })?;
writer.finish()?;

let mut reader = TypedReader::<Tick>::open("ticks.fwob")?;
assert_eq!(reader.read_frame(0)?.unwrap().price, 500);

let mut editor = TypedEditor::<Tick>::open("ticks.fwob")?;
editor.delete_ranges(&[0..1])?;
# Ok::<(), fwob::Error>(())

Fixed-width UTF-8 fields can use fwob_core::FixedString<N>. Values are space-padded to exactly N bytes and rejected when their encoded byte length exceeds the declared width. The typed API also re-exports fwob_core::Decimal with the legacy 16-byte decimal representation. Ordered keys may be integers, f32, f64, or Decimal. String-table fields may use StringIndex8, StringIndex16, StringIndex (32-bit), or StringIndex64. On v2, integer fields may declare Unix epoch semantics with #[fwob(timestamp = "seconds")] or the millisecond, microsecond, and nanosecond variants. Table and Markdown output render those fields as UTC.

Command Examples

fwob verify ticks.fwob
fwob inspect ticks.fwob
fwob info
fwob info data archive/ticks.fwob md
fwob create ticks-empty.fwob --template ticks.fwob
fwob convert ticks.fwob ticks-v2.fwob smallest 1MiB --zstd-level 9
fwob convert ticks.fwob ticks-columnar.fwob columnar-basic zstd
fwob convert v2 ticks.fwob ticks-delta.fwob columnar-delta zstd verify
fwob convert raw-files converted-files columnar-delta zstd --parallelism 8
fwob append ticks-v2.fwob new-ticks-1.fwob new-ticks-2.fwob verify
fwob split ticks.fwob parts 1000 2000 3000 zstd columnar-basic
fwob concat ticks-joined.fwob parts/ticks.part0.fwob parts/ticks.part1.fwob zstd
fwob concat v1 ticks-v1.fwob ticks-old.fwob ticks-new.fwob
fwob edit ticks-joined.fwob --title Renamed --append-string NASDAQ --set-semantic Time=unix-milliseconds
fwob find ticks-v2.fwob 100..200
fwob find ticks-v2.fwob 100 200..300 500.. ..50
fwob dump ticks-v2.fwob 100 200..300 csv
fwob dump ticks-v2.fwob raw > ticks.txt
fwob delete ticks-v2.fwob 100 200 local-repack verify
fwob delete ticks-v2.fwob 100 200 repack-to-end zstd columnar-basic compress-partial-page
fwob verify ticks-v2.fwob
fwob bench range ticks-v2.fwob --first-key-i32 100 --last-key-i32 200

fwob create and fwob concat refuse to overwrite an existing output. Pass --force (or --overwrite) to replace it explicitly.

Append and concat assume every input file is internally valid. They validate cross-file schema, string-table, and key-boundary compatibility without rescanning each complete input. Run fwob verify FILE first when input corruption is a concern. Mixed v1/v2 concat warns when v1's missing semantic metadata requires a relaxed comparison. V2 output preserves available v2 semantics; forced v1 output drops them because v1 has no semantic metadata slot.

fwob info summarizes FWOB files as a padded table. With no paths it lists immediate *.fwob files in the current directory. Each supplied path may be a file or directory; directory discovery is non-recursive. Add table, md, csv, or jsonl to select the output format. The summary includes path, format, title, frame type, key-field index, field count, frame length/count, boundary keys, raw frame bytes, and physical-to-raw ratio.

fwob convert accepts file-to-file, file-to-directory, and directory-to-directory conversion. Directory input discovers immediate *.fwob files, preserves each filename, and creates the output directory when needed. For file input, a nonexistent extensionless output is treated as a directory; an explicit output filename should use the .fwob extension. Files are converted concurrently; --parallelism N sets the worker limit and defaults to the logical CPU count. Progress lines may interleave on stderr and include the input filename, while each file's structured stdout summary is printed atomically.

V2 writes default consistently across convert, append, concat, delete, and split: zstd level 6, columnar-basic encoding, and estimate-shrink packing. New v2 outputs use 512 KiB pages unless another page size is supplied; append and delete retain the existing file's fixed page size. Create, convert, and concat default to v2 output; pass v1 explicitly when v1 output is required.

Convert, append, concat, split, and delete write progress diagnostics to stderr and keep structured TOML on stdout. Mutation summaries contain one operation-specific section followed by [parameters], [packing], [compression], and [page_stats]; the operation section includes elapsed_seconds.

Positional tokens are case-sensitive. For example, v2, zstd, and 1MiB are tokens; V2, ZSTD, and 1MIB are treated as paths or values rather than their lowercase token forms.

Tuning Parameters