databendlabs/databend · error

no data found

Error message

no data found

What it means

validate_version reads the first line of a streamed data dump (meta backup/upgrade payload) via lines.peek(); if the iterator is empty — no data at all — it returns "no data found". It guards against being handed an empty file or stream where a version header is mandatory.

Solutions

1. Check the dump file exists and is non-empty (ls -l / wc -c) before running the restore/upgrade
2. Re-create the backup/export; the source produced no data
3. Verify you are pointing the tool at the correct input file, not a placeholder path
4. If streaming, confirm the upstream writer actually flushed and closed successfully

Example fix

// before
let f = File::open(&path)?;
validate_version(BufReader::new(f).lines().peekable())?;
// after
let meta = std::fs::metadata(&path)?;
anyhow::ensure!(meta.len() > 0, "dump file {} is empty", path.display());
let f = File::open(&path)?;

let md = std::fs::metadata(&dump_path)?;
anyhow::ensure!(md.len() > 0, "dump {} is empty", dump_path.display());

fn has_first_line<R: BufRead>(r: &mut Peekable<Lines<R>>) -> bool { r.peek().is_some() }

match validate_version(&mut lines) {
    Err(e) if e.to_string() == "no data found" => bail!("dump file is empty; regenerate the backup"),
    other => other?,
}

When it happens

Trigger: Calling validate_version with an empty reader: zero lines remain in the Peekable<Lines<B>>, so peek() returns None.

Common situations: Restoring a meta data backup from a truncated or empty file; piping an empty stdin to the meta upgrade tool; a failed export produced a 0-byte dump.

Understand the failure class

Background: EmptyResultError / "no results found": when an API or scraper succeeds but returns zero rows — this error's family across 9 libraries.

Related errors

• invalid data version
• Unsupported format for
• Unsupported source type. Expected path, pandas.DataFrame…
• Access denied: is outside allowed directories
• rename_database: src (db) should exist

AI-assisted analysis of databendlabs/databend@288d84d76e (2026-09-11). Data as JSON: /api/errors/95a59acfd687e44a. Report an issue: GitHub.

Appendix: source

Thrown at src/meta/control/src/reading.rs:33

//! Supporting utilities for reading exported data.

use std::io::BufRead;
use std::io::Lines;
use std::iter::Peekable;

use databend_meta::raft_config::data_version::DATA_VERSION;
use databend_meta::raft_config::data_version::DataVersion;
use databend_meta::store_compat::ondisk::TREE_HEADER;
use databend_meta::store_compat::sled_compat::key_spaces::RaftStoreEntry;

/// Import from lines of exported data and Return the max log id that is found.
pub fn validate_version<B: BufRead + 'static>(
    lines: &mut Peekable<Lines<B>>,
) -> anyhow::Result<DataVersion> {
    #[allow(clippy::useless_conversion)]
    let first = lines
        .peek()
        .ok_or_else(|| anyhow::anyhow!("no data found"))?;

    let first_line = match first {
        Ok(l) => l,
        Err(e) => {
            return Err(anyhow::anyhow!("{}", e));
        }
    };

    // First line is the data header that containing version.
    let version = read_version(first_line)?;

    if !DATA_VERSION.is_compatible(version) {
        return Err(anyhow::anyhow!(
            "invalid data version: {:?}, This program version is {:?}; The latest compatible program version is: {:?}",
            version,
            DATA_VERSION,
            version.max_compatible_working_version(),
        ));

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