spring data jpa @index unable to create index

spring data jpa annotations may be used to create the index table, the specific use is as follows: 

@Data
@Entity
@Table(name = "pre_lcas_syslog" , indexes = {@Index(name = "index_timestamp", columnList = "timestamp")})
public class Xxx extends BaseEntity implements Serializable {
    private String xxx;
　　 private String timestamp;
}

The code above can successfully create an index, however, if the specified index name is "i_timestamp", when the program starts, the console has been successfully created an index print, but the database view, it is no corresponding index;

 

I did not know why, there may be an internal database with pg naming conflict, the only note of this phenomenon, subsequent analysis;