prestodb/presto · error · IllegalArgumentException

Expected column to be a timestamp type but is

Error message

Expected column to be a timestamp type but is 

What it means

PrestoResultSet.getTimestamp parses the column only when the column's reported type name is 'timestamp' or 'timestamp with time zone'. If the column holds any other Presto type, the driver throws an IllegalArgumentException naming the actual server type. It signals a caller bug: getTimestamp was invoked on a non-timestamp column instead of using the matching getter.

Source

Thrown at presto-jdbc/src/main/java/com/facebook/presto/jdbc/PrestoResultSet.java:346

        if (columnInfo.getColumnTypeName().equalsIgnoreCase("timestamp")) {
            try {
                return new Timestamp(TIMESTAMP_FORMATTER.withZone(localTimeZone).parseMillis(String.valueOf(value)));
            }
            catch (IllegalArgumentException e) {
                throw new SQLException("Invalid timestamp from server: " + value, e);
            }
        }

        if (columnInfo.getColumnTypeName().equalsIgnoreCase("timestamp with time zone")) {
            try {
                return new Timestamp(TIMESTAMP_WITH_TIME_ZONE_FORMATTER.parseMillis(String.valueOf(value)));
            }
            catch (IllegalArgumentException e) {
                throw new SQLException("Invalid timestamp from server: " + value, e);
            }
        }

        throw new IllegalArgumentException("Expected column to be a timestamp type but is " + columnInfo.getColumnTypeName());
    }

    @Override
    public InputStream getAsciiStream(int columnIndex)
            throws SQLException
    {
        throw new NotImplementedException("ResultSet", "getAsciiStream");
    }

    @Override
    public InputStream getUnicodeStream(int columnIndex)
            throws SQLException
    {
        throw new SQLFeatureNotSupportedException("getUnicodeStream");
    }

    @Override
    public InputStream getBinaryStream(int columnIndex)

View on GitHub (pinned to 55bb57d202)

Solutions

1. Read the column with the getter matching its actual Presto type (getString/getDate for date/varchar, getLong for bigint)
2. Cast in SQL: SELECT CAST(col AS timestamp) or CAST(col AS timestamp with time zone)
3. Branch on ResultSetMetaData.getColumnTypeName(i) before choosing a getter
4. Fix upstream schema drift so the column is genuinely timestamp typed

Example fix

// before
Timestamp ts = rs.getTimestamp("event_time"); // event_time is varchar -> IllegalArgumentException
// after
String raw = rs.getString("event_time");
Timestamp ts = raw != null ? Timestamp.valueOf(raw) : null;
// or in SQL: SELECT CAST(event_time AS timestamp) AS event_time

ResultSetMetaData md = rs.getMetaData();
String typeName = md.getColumnTypeName(colIndex);
if (!typeName.equalsIgnoreCase("timestamp") && !typeName.equalsIgnoreCase("timestamp with time zone")) {
    throw new IllegalStateException("Column " + colIndex + " is not a timestamp but " + typeName);
}
Timestamp ts = rs.getTimestamp(colIndex);

static boolean isTimestampColumn(ResultSetMetaData md, int idx) throws SQLException {
    String t = md.getColumnTypeName(idx);
    return t != null && (t.equalsIgnoreCase("timestamp") || t.equalsIgnoreCase("timestamp with time zone"));
}

Timestamp ts;
try {
    ts = rs.getTimestamp(idx);
} catch (IllegalArgumentException e) {
    ts = Timestamp.valueOf(rs.getString(idx));
}

When it happens

Trigger: Calling ResultSet.getTimestamp(i) or getTimestamp(label) on a column whose Presto type is not timestamp/timestamp with time zone (e.g. date, varchar, bigint, map, row). Also occurs after schema drift changes a column from timestamp to another type while the code still calls getTimestamp.

Common situations: Code that calls getTimestamp on a 'date' or varchar column; SELECT with CAST(col AS varchar) of a timestamp read via getTimestamp; schema evolution in upstream tables; generic result-set mappers that call getTimestamp unconditionally.

Related errors

• No wrapper for
• Result set type must be TYPE_FORWARD_ONLY
• Result set concurrency must be CONCUR_READ_ONLY
• Invalid date from server:
• Expected column to be a time type but is

AI-assisted analysis of prestodb/presto@55bb57d202 (2026-09-04). Data as JSON: /api/errors/d7bc20e7d9670330. Report an issue: GitHub.