Select-Tuning

[omata]

So hier mal ein Vorschlag (ungetestet)

SQL-Code:

CREATE GLOBAL TEMPORARY TABLE temp_data (
  vv_id INT PRIMARY KEY,
  vv_name VARCHAR(100),
  vv_alter INT,
       ...
  vv_gruppe VARCHAR(100)
);


INSERT INTO temp_data
SELECT vv_id,
       vv_name,
       vv_alter,
       ...
       p.vv_gruppe,
FROM vv_personas p
WHERE vv_alter = 25
  AND vv_xyz IS NULL
  AND vv_abc IS NULL;


SELECT p.*, g.anzahl
FROM temp_data p
LEFT JOIN (SELECT vv_gruppe, COUNT(*) anzahl
           FROM temp_data
           GROUP BY vv_gruppe) g
  ON p.vv_gruppe = g.vv_gruppe;


DROP GLOBAL TEMPORARY TABLE temp_data;