Obtain CDR from DB

Every minute, Class4 pushes CDRs into DB.

You can obtain all CDRs in the following tables:

 public | client_cdr20200412                               | table    | class4_dial | 252 MB     | 
 public | client_cdr20200413                               | table    | class4_dial | 293 MB     | 
 public | client_cdr20200414                               | table    | class4_dial | 216 MB     | 
 public | client_cdr20200415                               | table    | class4_dial | 318 MB     | 
 public | client_cdr20200416                               | table    | class4_dial | 353 MB     |