Sybase CEP Server performs base64 encoding and decoding for BLOB data when you store it as character data.
Keep your data within the maximum amount that can be exchanged with the remote database server. The limiting factor may be the amount that the external server character data type can hold, or may be limited by DBDriverCharBufferSize. The longest BLOB you can store on such a server is approximately 3/4 the length of the longest character string that the external server can store or that Sybase CEP Server can exchange with the remote database server.