Performance Tuning "Select All" vs "Select Then Delete"

Question

Dear Experts,
Please tell me which one has better prefromance between
SELECT a~vbeln
         a~kunnr
         a~bukrs_vf
         a~vkorg
         a~vtweg
         a~spart
         a~augru
         a~vbtyp
         a~auart
         a~bstnk
         b~kunnr
  INTO TABLE ivbak
  FROM vbak AS a
  INNER JOIN vbpa AS b
    ON  bvbeln EQ avbeln
    AND b~parvw EQ c_shipto
  WHERE a~kunnr IN s_kunnr AND
        a~vkorg EQ p_vkorg AND
        a~vtweg IN s_vtweg AND
        a~spart IN s_spart and
        a~auart in s_auart .
  DELETE ivbak WHERE NOT (
        vbeln IN s_vbeln  AND
        augru EQ space    AND
        vbtyp EQ s_order AND
        kunno IN s_kunev ).
  DELETE ivbak WHERE auart EQ ordertype2
                   OR auart EQ ordertype1.
  DELETE ADJACENT DUPLICATES FROM ivbak COMPARING ALL FIELDS.
AND
SELECT a~vbeln
         a~kunnr
         a~bukrs_vf
         a~vkorg
         a~vtweg
         a~spart
         a~augru
         a~vbtyp
         a~auart
         a~bstnk
         b~kunnr
  INTO TABLE i_vbak
  FROM vbak AS a
  INNER JOIN vbpa AS b
    ON  bvbeln EQ avbeln
    AND b~parvw EQ c_shipto
  WHERE a~kunnr IN s_kunnr AND
        a~vkorg EQ p_vkorg AND
        a~vtweg IN s_vtweg AND
        a~spart IN s_spart AND
        a~auart in s_auart AND
        a~vbeln NOT IN s_vbeln AND
        a~augru NE SPACE AND
        a~vbtyp NE s_order OR
        (auart EQ ordertype2
                   OR auart EQ ordertype1)

Answer 1

as a general recommendation, I would say that the second one should be faster.
But every rule has exceptions and your case could be such an exception. You really have to try booth version is a small test programm,
execute them with GET RUNTIME FIELD start and stop.
And check the SQL Trace. It can happen that version gets a different access path with different indexes. This can take much longer than the delete.
Siegfried