What causes "`compaction.write_parquet_compression` must be one of {:?}, got: {}" in risingwavelabs/risingwave?

Set the value to one of the valid codec names, e.g. `zstd` or `snappy` (lowercase).

`compaction.write_parquet_compression` must be one of

Error message

`compaction.write_parquet_compression` must be one of {:?}, got: {}

What it means

When altering an Iceberg sink config, `compaction.write_parquet_compression` must name a Parquet codec the writer supports. The value is lowercased and checked against a fixed list (uncompressed, snappy, gzip, lzo, brotli, lz4, zstd, etc.); anything else fails validation.

Solutions

Set the value to one of the valid codec names, e.g. `zstd` or `snappy` (lowercase).
Remove the property to use the default compression codec.
If you need codec-level options (like zstd levels), remove the level suffix and check whether a separate tuning option exists.

Example fix

-- before
ALTER SINK s SET ('compaction.write_parquet_compression'='zstd-3');
-- after
ALTER SINK s SET ('compaction.write_parquet_compression'='zstd');

Defensive patterns

Strategy: validation

Validate before calling

const VALID_CODECS: &[&str] = &["uncompressed","snappy","gzip","lzo","brotli","lz4","zstd"];
fn valid_codec(cfg: &std::collections::BTreeMap<String, String>) -> Result<(), String> {
    if let Some(c) = cfg.get("compaction.write_parquet_compression") {
        if !VALID_CODECS.contains(&c.to_lowercase().as_str()) {
            return Err(format!("write_parquet_compression must be one of {VALID_CODECS:?}, got {c}"));
        }
    }
    Ok(())
}

Prevention

Use bare codec names without levels or variants (no 'zstd-3', no 'lz4_raw').
Copy codec names from the error message's valid list.
Keep a shared constants list in your deployment tooling matching the engine.

When it happens

Trigger: `ALTER SINK ... SET` with `compaction.write_parquet_compression` set to a misspelled or unsupported codec such as `Snappy!`, `zstd1`, `GZIP_LEVEL6`, or `lz4_raw`.

Common situations: Users copying codec names from other engines that accept extra variants (e.g. `lz4_raw`, `zstd-1`) or appended compression levels; case-sensitive assumptions (lowercasing is applied, so casing alone is fine).

Understand the failure class

Background: Invalid enum value errors: "Unknown type", "Invalid scope", "must be one of" — when a string is not on the library's allowed list — this error's family across 23 libraries.

Related errors

AI-assisted analysis of risingwavelabs/risingwave@6469eb736d (2026-09-11). Data as JSON: /api/errors/681f7f73a39a8fc4. Report an issue: GitHub.

Appendix: source

Thrown at src/connector/src/sink/iceberg/mod.rs:366

        if let Some(max_row_group_bytes) = iceberg_config.write_parquet_max_row_group_bytes
            && max_row_group_bytes == 0
        {
            bail!("`compaction.write_parquet_max_row_group_bytes` must be greater than 0");
        }

        // Validate parquet compression codec
        if let Some(ref compression) = iceberg_config.write_parquet_compression {
            let valid_codecs = [
                "uncompressed",
                "snappy",
                "gzip",
                "lzo",
                "brotli",
                "lz4",
                "zstd",
            ];
            if !valid_codecs.contains(&compression.to_lowercase().as_str()) {
                bail!(
                    "`compaction.write_parquet_compression` must be one of {:?}, got: {}",
                    valid_codecs,
                    compression
                );
            }
        }

        Ok(())
    }

    async fn new_log_sinker(&self, writer_param: SinkWriterParam) -> Result<Self::LogSinker> {
        let writer = IcebergSinkWriter::new(
            self.config.clone(),
            self.param.clone(),
            writer_param.clone(),
            self.upsert_primary_key_column_names.clone(),
        );

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