What causes "unsupported column type '%s' for column '%s'" in prestodb/presto?

Change the column to a supported primitive type (boolean, bigint, double, varchar, date, time, timestamp)

prestodb/presto · error · IllegalArgumentException

unsupported column type '%s' for column '%s'

Error message

unsupported column type '%s' for column '%s'

What it means

JsonRowDecoderFactory.throwUnsupportedColumnType signals that a column's type cannot be decoded by any JSON field decoder for the given setup. When the column has no dataFormat, the message reports just the column type and name. The type is simply not in the set the JSON decoder supports (e.g. row, map, array or other unsupported types).

Source

Thrown at presto-record-decoder/src/main/java/com/facebook/presto/decoder/json/JsonRowDecoderFactory.java:90

                case "milliseconds-since-epoch":
                    return new MillisecondsSinceEpochJsonFieldDecoder(column);
                case "rfc2822":
                    return new RFC2822JsonFieldDecoder(column);
                case "":
                    return new DefaultJsonFieldDecoder(column);
                default:
                    throw new IllegalArgumentException(format("unknown data format '%s' used for column '%s'", column.getDataFormat(), column.getName()));
            }
        }
        catch (IllegalArgumentException e) {
            throw new PrestoException(GENERIC_USER_ERROR, e);
        }
    }

    public static JsonFieldDecoder throwUnsupportedColumnType(DecoderColumnHandle column)
    {
        if (column.getDataFormat() == null) {
            throw new IllegalArgumentException(format("unsupported column type '%s' for column '%s'", column.getType().getDisplayName(), column.getName()));
        }
        throw new IllegalArgumentException(format("unsupported column type '%s' for column '%s' with data format '%s'", column.getType(), column.getName(), column.getDataFormat()));
    }
}

View on GitHub (pinned to 55bb57d202)

Solutions

Change the column to a supported primitive type (boolean, bigint, double, varchar, date, time, timestamp)
Drop the unsupported column from the table definition
Represent structured JSON via varchar and parse in queries (json_extract)
Check connector docs for supported JSON decoder column types

Example fix

// before
{"name":"payload","type":"map(varchar, varchar)"}
// after
{"name":"payload","type":"varchar"} then json_extract(payload, '$.x')

Defensive patterns

Strategy: validation

Validate before calling

boolean ok = java.util.Set.of("boolean","bigint","integer","smallint","tinyint","double","real","varchar","date","time","time with time zone","timestamp").contains(column.getType().getDisplayName().toLowerCase());

Try / catch

try { decoder = JsonRowDecoderFactory.create(...); } catch (PrestoException e) { log.error("unsupported column type: " + e.getMessage()); throw new ConfigError(e); }

Prevention

Restrict record-decoder columns to supported primitive types
Parse nested JSON via varchar + json_extract in queries instead of complex types
Review connector docs for type support before adding columns
Add a definition lint step that checks column types against the whitelist

When it happens

Trigger: Declaring a Kafka/record column whose type (e.g. a complex type like array(F) or map(...)) has no JSON field decoder implementation and no dataFormat set, so decoder selection fails and calls throwUnsupportedColumnType.

Common situations: Overly ambitious table DDL trying to map nested JSON structures to complex Presto types; schema copied from a Hive connector where complex types are supported.

Related errors

AI-assisted analysis of prestodb/presto@55bb57d202 (2026-09-04). Data as JSON: /api/errors/e107cb057223a9f6. Report an issue: GitHub.