postgresql – load json file to postgres table

I have created one table in Postgres as:

 CREATE TABLE temp_test_table
( 
  technology       character varying(255),
  vendor           character varying(255),
  name             character varying(255),
  temporal_unit    character varying(255),
  regional_unit    character varying(255),
  dataset_metadata json,
  rk               character varying(255)
);

and I have a json file below as:

(xyz@innolx20122 ~)$ cat cgs_test.json
{"technology":"AAA","vendor":"XXX","name":"RBNI","temporal_unit":"hour","regional_unit":"cell","dataset_metadata":"{"name": "RBNI", "temporal_unit": "hour", "technology": "LTE", "is_dimension": false, "timestamp_column_pattern": "yyyyMMddHHmmss", "data_type": "PM", "source_name": "RBNI", "intervals_epoch_seconds": ((1609941600, 1609945200)), "identifier_column_names": ("CELLID", "CELLNAME", "radio_frequency_band", "ENODEBID", "ENODEBNAME", "SBNID", "SITEID", "SITENAME", "CLUSTER_PRIORITY", "CP_SITE", "IBC", "NETWORK_TIER", "SITE_TYPE", "T3_FLAG", "CLUSTERID", "CLUSTERNAME", "REGION", "NETWORK"), "vendor": "ZTE", "timestamp_column_name": "COLLECTTIME", "regional_unit": "cell"}","rk":1}
{"technology":"LTE","vendor":"XXX","name":"RRCADD","temporal_unit":"hour","regional_unit":"cell","dataset_metadata":"{"name": "RRCADD", "temporal_unit": "hour", "technology": "AAA", "is_dimension": false, "timestamp_column_pattern": "yyyyMMddHHmmss", "data_type": "PM", "source_name": "RRCADD", "intervals_epoch_seconds": ((1609941600, 1609945200)), "identifier_column_names": ("CELLID", "CELLNAME", "radio_frequency_band", "ENODEBID", "ENODEBNAME", "SBNID", "SITEID", "SITENAME", "CLUSTER_PRIORITY", "CP_SITE", "IBC", "NETWORK_TIER", "SITE_TYPE", "T3_FLAG", "CLUSTERID", "CLUSTERNAME", "REGION", "NETWORK"), "vendor": "XXX", "timestamp_column_name": "COLLECTTIME", "regional_unit": "cell"}","rk":1}

not sure why it was not able to load

copy temp_test_table(technology,vendor,name,temporal_unit,regional_unit,dataset_metadata,rk) FROM '/home/eksinvi/cgs_test.json';


ERROR:  value too long for type character varying(255)
CONTEXT:  COPY temp_test_table, line 1, column technology: "{"technology":"AAA","vendor":"XXX","name":"RBNI","temporal_unit":"hour","regional_unit":"cell","data..."