Search string field in elasticsearch -

i have device_model field, example this:

lenovo ideatab a3000-h[graphicsdevicename: powervr sgx 544mp; graphicsdevicevendor: imagination technologies; graphicsdeviceversion: opengl es 2.0 build 1.9@2204701; graphicsmemorysize: 60; operatingsystem: android os 4.2.2 / api-17 (jdq39/a3000_a422_003_026_130823_ww_sms_fuse); processorcount: 4; processortype: armv7 vfpv3 neon; systemmemorysize: 974; maxtexturesize: 4096]

i want aggregate know devices:

"aggs" : {         "devices" : {             "terms" : { "field" : "device_model",                 "size": 0             }         }     } 

but returns me 1 words aggregation this:

"aggregations": {       "user-ids": {          "doc_count_error_upper_bound": 0,          "sum_other_doc_count": 0,          "buckets": [             {                "key": "android",                "doc_count": 20851             },             {                "key": "api",                "doc_count": 20851             },             {                "key": "es",                "doc_count": 20851             }, 

but want see whole field. should elasticsearch not divide string field when aggregated?