What causes "Invalid argument , should have 2 parts" in apache/seatunnel?

Format parameterized transforms as transform[width,column], e.g. bucket[16,id] or truncate[10,name]

apache/seatunnel · error · IllegalArgumentException

Invalid argument , should have 2 parts

Error message

Invalid argument , should have 2 parts

What it means

SchemaUtils.transformArgPair parses the comma-separated argument list inside a parameterized partition transform like bucket[16,id] or truncate[10,name]. It requires exactly two parts: column name and width. If the split doesn't yield exactly two parts, it throws IllegalArgumentException 'Invalid argument <argsStr>, should have 2 parts'.

Source

Thrown at seatunnel-connectors-v2/connector-iceberg/src/main/java/org/apache/seatunnel/connectors/seatunnel/iceberg/utils/SchemaUtils.java:377

                                    Pair<String, Integer> args = transformArgPair(matcher.group(2));
                                    specBuilder.truncate(args.first(), args.second());
                                    break;
                                }
                            default:
                                throw new UnsupportedOperationException(
                                        "Unsupported transform: " + transform);
                        }
                    } else {
                        specBuilder.identity(partitionField);
                    }
                });
        return specBuilder.build();
    }

    private static Pair<String, Integer> transformArgPair(String argsStr) {
        String[] parts = argsStr.split(",");
        if (parts.length != 2) {
            throw new IllegalArgumentException(
                    "Invalid argument " + argsStr + ", should have 2 parts");
        }
        return Pair.of(parts[0].trim(), Integer.parseInt(parts[1].trim()));
    }
}

View on GitHub (pinned to cf67b549a7)

Solutions

Format parameterized transforms as transform[width,column], e.g. bucket[16,id] or truncate[10,name]
Count the comma-separated parts in the bracketed argument string — must be exactly 2
Check for stray/missing commas in the partition config
If using identity or simple temporal transforms, drop the bracketed argument entirely instead

Example fix

// before
partition = { transform = "bucket[16]" }
// after
partition = { transform = "bucket[16,id]" }

Defensive patterns

Strategy: validation

Validate before calling

String inner = transformStr.substring(transformStr.indexOf('[') + 1, transformStr.indexOf(']'));
String[] parts = inner.split(",");
if (parts.length != 2) {
    throw new IllegalArgumentException("Transform args must be [width,column]: " + inner);
}

Try / catch

try {
    Pair<String,Integer> arg = SchemaUtils.transformArgPair(argsStr);
} catch (IllegalArgumentException e) {
    log.error("Bad partition transform args '{}': use e.g. bucket[16,id]", argsStr);
    throw e;
}

Prevention

Always include both width and column inside the brackets: bucket[16,col]
Do not use engine-specific syntax like bucket[16](col)
Count commas before saving partition config
Cover transform parsing with unit tests using representative config strings

When it happens

Trigger: A transform argument string with the wrong number of comma-separated parts, e.g. 'bucket[16]' argument portion '16' (one part) or 'bucket[16,col,extra]' (three parts) passed into SchemaUtils while building the partition spec.

Common situations: Users writing Iceberg-style 'bucket[16](col)' syntax where the connector expects 'bucket[16,col]'; missing column name; stray commas from copy-paste; omitting the column in the bracketed argument.

Understand the failure class

Background: "Invalid ... format", "must be in format X", "does not look like a ..." — invalid argument format errors across CLI tools and libraries — this error's family across 17 libraries.

Related errors

AI-assisted analysis of apache/seatunnel@cf67b549a7 (2026-09-10). Data as JSON: /api/errors/b28ecb8d7a239690. Report an issue: GitHub.