tursodatabase/turso · error · ValueError

each sweep file must have a distinct positive connection…

Error message

each sweep file must have a distinct positive connection count

What it means

read_sweep aggregates multiple FTS benchmark sweep CSV files into one plot series keyed by connection count. It raises this ValueError when a file's 'connections' value is zero/negative or duplicates a connection count already seen in another sweep file, because the plot needs one distinct x-axis point per file.

Solutions

Rerun the benchmark sweep with a unique, positive connection count for each result file.
Remove duplicate sweep files that record the same connection count.
Fix the CSV generation so the 'connections' column always holds a positive integer.

Example fix

# before
python plot-fts.py results/c8.csv results/c8.csv
# after
python plot-fts.py results/c1.csv results/c8.csv results/c32.csv

Defensive patterns

Strategy: validation

Validate before calling

import csv
conns = [int(next(csv.DictReader(open(p))['connections'])) for p in paths]
assert all(c > 0 for c in conns), 'all connection counts must be positive'
assert len(set(conns)) == len(conns), 'connection counts must be distinct across sweep files'

Try / catch

try:
    config, points = read_sweep(paths)
except ValueError as e:
    if 'distinct positive connection count' in str(e):
        print('Fix: rerun sweeps with unique, positive connection counts')
    else:
        raise

Prevention

Name sweep result files by connection count and verify uniqueness before plotting.
Never pass the same sweep file twice on the command line.
Add a sanity check in the benchmark harness that connections is a positive integer.

When it happens

Trigger: Calling read_sweep (via main) with sweep CSVs where two files record the same 'connections' value, or a file records connections <= 0.

Common situations: Copying a sweep result file and forgetting to rerun with a different connection count; a buggy benchmark run writing connections=0; passing the same file twice on the command line.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

AI-assisted analysis of tursodatabase/turso@8d4a589f8d (2026-09-20). Data as JSON: /api/errors/48d6ed22b075f370. Report an issue: GitHub.

Appendix: source

Thrown at perf/fts/plot/plot-fts.py:57

    configuration, samples = (
        read_sweep(args.csv_files, args.percentile) if args.sweep else read_runs(args.csv_files, args.percentile)
    )
    for output in args.output or [Path("fts.png"), Path("fts.pdf")]:
        if args.sweep:
            plot_sweep(configuration, samples, output, args.relative)
        else:
            plot(configuration, samples, output)
        print(f"wrote {output}")


def read_sweep(paths, percentile="p50"):
    configuration = None
    points = {}
    for path in paths:
        current, samples = read_runs([path], percentile)
        connections = int(current.pop("connections"))
        if connections <= 0 or connections in points:
            raise ValueError("each sweep file must have a distinct positive connection count")
        if configuration is None:
            configuration = current
        if current != configuration or (points and set(samples) != set(next(iter(points.values())))):
            raise ValueError("sweep files must match benchmark, sample budget, fixture and engine/mode series")
        points[connections] = samples
    if not points:
        raise ValueError("no sweep results found")
    return configuration, dict(sorted(points.items()))


def read_runs(paths, percentile="p50"):
    configuration = None
    samples = {}
    expected_series = None
    for path in paths:
        current, runs = read_file(path, percentile, samples)
        if configuration is None:
            configuration = current

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