오라클 Blob 용량 표시 byte, kbyte, mbyte, gbyte select --count(*) sum(dbms_lob.getlength(a.blob_col)) byte , sum(dbms_lob.getlength(a.blob_col)/1024) kbyte , sum(dbms_lob.getlength(a.blob_col)/1024/1024) mbyte , sum(dbms_lob.getlength(a.blob_col)/1024/1024/1024) gbyte from tab1 a