MigrateFromOTRS: handle Blob columns

[bschmalhofer]

It looks like Blob Columns were never correctly converted between dabase types that have different DirectBlob settings.
Either fix this, or remove the remnants of the code that once did the conversion.

Maybe check whether there still is a need to support Base64 encoded binary data.

[bschmalhofer]

I added support for Blob conversion in Kernel::System::MigrateFromOTRS::CloneDB::Driver::Base in the rel-10_0 branch. This should not affect MySQL to MySQL migration, as the DB::DirectBlob check is still honored.

However it looks like the conversion is not as straightforward as assumed. Let's take for example the table columns article_data_mime.email and sysconfig_default_version.description. For the first column there is an explicit check of DB::DirectBlob in Kernel::System::Ticket::Article::Backend::MIMEBase::ArticleStorageDB.

    # encode attachment if it's a postgresql backend!!!
    if ( !$DBObject->GetDatabaseFunction('DirectBlob') ) {

        $Kernel::OM->Get('Kernel::System::Encode')->EncodeOutput( \$Param{Email} );

        $Param{Email} = encode_base64( $Param{Email} );
    }

But, for the latter column, there seems to be no such check in Kernel::System::SysConfig::DB.

This seems to indicate that some more testing of the PostgreSQL to MySQL migration needs to be done. As this is not super urgent, let's move the issue to OTOBO 10.1.x.

[StefanRother-OTOBO]

Dublicate with Issue #1006, #800 and #601