apache/seatunnel · warning

enable_file_split=true but file_format_type={} does not supp

Error message

enable_file_split=true but file_format_type={} does not support file split. Falling back to non-splitting mode.

What it means

WARN logged by FileSplitStrategyFactory.initFileSplitStrategy when the user enabled file splitting (enable_file_split=true) but the chosen file_format_type's FileFormat does not support splitting. The factory silently degrades to DefaultFileSplitStrategy (whole-file reads), so the job runs but without the requested parallel per-file splitting.

Source

Thrown at seatunnel-connectors-v2/connector-file/connector-file-base/src/main/java/org/apache/seatunnel/connectors/seatunnel/file/source/split/FileSplitStrategyFactory.java:44

import org.apache.seatunnel.connectors.seatunnel.file.exception.FileConnectorErrorCode;

import lombok.extern.slf4j.Slf4j;

import java.util.Objects;

import static org.apache.seatunnel.connectors.seatunnel.file.config.FileBaseSourceOptions.DEFAULT_ROW_DELIMITER;

@Slf4j
public class FileSplitStrategyFactory {

    public static FileSplitStrategy initFileSplitStrategy(
            ReadonlyConfig readonlyConfig, HadoopConf hadoopConf) {
        if (!readonlyConfig.get(FileBaseSourceOptions.ENABLE_FILE_SPLIT)) {
            return new DefaultFileSplitStrategy();
        }
        FileFormat fileFormat = readonlyConfig.get(FileBaseSourceOptions.FILE_FORMAT_TYPE);
        if (!fileFormat.supportFileSplit()) {
            log.warn(
                    "enable_file_split=true but file_format_type={} does not support file split. "
                            + "Falling back to non-splitting mode.",
                    fileFormat);
            return new DefaultFileSplitStrategy();
        }
        CompressFormat compressCodec = readonlyConfig.get(FileBaseSourceOptions.COMPRESS_CODEC);
        ArchiveCompressFormat archiveCompressCodec =
                readonlyConfig.get(FileBaseSourceOptions.ARCHIVE_COMPRESS_CODEC);
        if (compressCodec != CompressFormat.NONE
                || archiveCompressCodec != ArchiveCompressFormat.NONE) {
            log.warn(
                    "enable_file_split=true but compress_codec={} or archive_compress_codec={} is not NONE. "
                            + "Falling back to non-splitting mode.",
                    compressCodec,
                    archiveCompressCodec);
            return new DefaultFileSplitStrategy();
        }

View on GitHub (pinned to cf67b549a7)

Solutions

1. Set file_format_type to a split-supporting format (e.g. Parquet, ORC) if you need split-based parallelism.
2. Otherwise accept the fallback — remove enable_file_split=true from config to make intent explicit and silence the warning.
3. Increase source parallelism via other means (more files/partitions) if whole-file mode is required.

Example fix

// before
enable_file_split = true
file_format_type = "csv"
// after (either disable the option...)
file_format_type = "csv"
// ...or use a splittable format
enable_file_split = true
file_format_type = "parquet"

// Before enabling split mode, check format support
FileFormat fmt = ReadonlyConfig get FILE_FORMAT_TYPE;
if (enableFileSplit && !fmt.supportFileSplit()) {
    throw new IllegalArgumentException(
        "file_format_type=" + fmt + " does not support file split");
}

// Java-style check
if (fileFormat instanceof SplittableFileFormat) { /* safe to enable split */ }

When it happens

Trigger: Config with enable_file_split=true and a FILE_FORMAT_TYPE whose format reports supportFileSplit()==false — e.g. CSV/text formats (or other formats lacking splittable readers) rather than splittable columnar formats.

Common situations: User expects text/CSV files to be split for parallelism; enabling the option while reading formats that only support whole-file reads; copying an option set from a Parquet/ORC job to a CSV job.

Understand the failure class

Background: "Invalid value" and "allowed values are" config errors: what your library rejected and how to fix it — this error's family across 41 libraries.

Related errors

• enable_file_split=true but compress_codec={} or archive_comp
• File format 'pdf' does not support writing.
• Fallback content comparison failed, fallback to COPY. source
• File checksum is not available, fallback to content comparis
• prepare method is not supported

AI-assisted analysis of apache/seatunnel@cf67b549a7 (2026-09-10). Data as JSON: /api/errors/787f15c15f689b31. Report an issue: GitHub.