presto-hive/src/main/java/io/prestosql/plugin/hive/metastore/MetastoreUtil.java/MetastoreUtil/toThriftDdl
class MetastoreUtil:    private static String toThriftDdl(String structName, List<Column> columns)
    {
        // Mimics function in Hive:
        // MetaStoreUtils.getDDLFromFieldSchema(String, List<FieldSchema>)
        StringBuilder ddl = new StringBuilder();
        ddl.append("struct ");
        ddl.append(structName);
        ddl.append(" { ");
        boolean first = true;
        for (Column column : columns) {
            if (first) {
                first = false;
            }
            else {
                ddl.append(", ");
            }
            ddl.append(typeToThriftType(column.getType().getHiveTypeName().toString()));
            ddl.append(' ');
            ddl.append(column.getName());
        }
        ddl.append("}");
        return ddl.toString();
    }