DBIx can't read SQL server 2008 varchar(max) column

[Thai Heng]

I use DBIx to retrieve some varchar(max) column, but the program is dead, not executed when retrieve only one row. The following is the output:

  c:\temp\perl\DBIx\hengaini>perl ecis_odbc.pl
  MyApp::Schema=HASH(0x33c928)
  select * from T_SEARCH where %s

my script as follows:

 
   #!/usr/bin/perl
use v5.14.2;
use strict;
use warnings;

use utf8;
use MyApp::Schema;
use open ":encoding(gbk)", ":std";

my $schema = MyApp::Schema->connect('dbi:ODBC:DSN=ecis_yl','sa','73545
+00',
{odbc_trace_file => 'c:\temp\odbc.trc',
                      odbc_trace => 1}
);

say $schema;
my $rs = $schema->resultset('Search');

while (my $search = $rs->next) {
   say $search->mysql;   
}

I use DBIx, and result 'Search' file Search.pm as follows:

   package MyApp::Schema::Result::Search;
    use base qw/DBIx::Class::Core/;
    __PACKAGE__->table('dbo.t_search');
    __PACKAGE__->add_columns(qw/ searchid searchname title mysql /);
   __PACKAGE__->set_primary_key('searchid');

   1;

The table "T_search" in SQL Server 2008 defination as follows :

    CREATE TABLE [dbo].[T_Search](
    [searchId] [varchar](10) NOT NULL,
    [searchName] [varchar](50) NOT NULL,
    [mysql] [varchar](max) NOT NULL,
    [formName] [varchar](30) NULL,
    [formAction] [varchar](30) NULL,
    [mykey] [varchar](30) NULL,
    [title] [varchar](120) NULL,
    [orderBy] [varchar](64) NULL,
    [groupBy] [varchar](30) NULL,
    [pageSize] [smallint] NOT NULL,
    [entityName] [varchar](30) NULL,
    [ds] [varchar](12) NULL,
    [remark] [varchar](80) NULL,
 CONSTRAINT [PK_T_SearchValue22] PRIMARY KEY NONCLUSTERED 
(
    [searchId] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY
+ = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]

GO

   select max(len(mysql)) from T_Search --10516

My questions are: 1. how to debug this question? 2. What's wrong? Thanks!