http://bugs.mysql.com/bug.php?id=68350
first time
call rozklad(2012) time 0.946 sec

second time
call rozklad(2012) time 46.55 sec

next time
call rozklad(2012) time sec

How to repeat:
DELIMITER $$

USE `dekanat`$$

DROP PROCEDURE IF EXISTS `rozklad`$$

CREATE DEFINER=`root`@`localhost` PROCEDURE `rozklad`(IN iRik YEAR)
BEGIN
SELECT
trozklad.ID
, trozpodil.Ses AS piv
, tpredmets.GroupID
, tpredmets.Name AS Predmet
, tgroups.Name AS Grupa
, CONCAT(tlogin.FName,' ', SUBSTR(tlogin.Name,1,1),'. ',
SUBSTR(tlogin.LName,1,1),'.') AS FIO
, trozklad.T
, CASE trozklad.Type WHEN 1 THEN 'Лек' WHEN 2 THEN 'Пр'
WHEN 3 THEN 'Лаб' END AS TYPE
, trozklad.Ses
, trozklad.God
, trozklad.Den
, trozklad.Para
, trozklad.Podgrupa
, tfakultet.Name AS Fakultet
, tnkp.Name AS NKP
, tfnavch.Name AS FNavch
, tkafedra.Name AS Kafedra
, tgroups.Kurs
, IF(trozklad.Type=1,tpredmets.PotokID,NULL) AS PotokID
, IF(trozklad.Type=2,tpredmets.PotokPrID,NULL) AS PotokPrID
, IF(trozklad.Type=3,tpredmets.PotokLabID,NULL) AS PotokLabID
, trozklad.Vichitano
, a.PotokLec
, a1.PotokPr
, a2.PotokLab

1. ,tpredmets.KafedraID
   , a3.Posada
   FROM
   trozklad
   INNER JOIN trozpodil ON (trozklad.RozpodilID = trozpodil.ID)
   INNER JOIN tpredmetsinfo ON (trozpodil.PredmetsInfoID =
   tpredmetsinfo.ID)
   INNER JOIN tlogin ON (tpredmetsinfo.LoginID = tlogin.ID)
   INNER JOIN tpredmets ON (tpredmetsinfo.PredmetsID = tpredmets.ID)
   INNER JOIN tkafedra ON (tpredmets.KafedraID = tkafedra.ID)
   INNER JOIN tgroups ON (tpredmets.GroupID = tgroups.ID)
   INNER JOIN tfnavch ON (tgroups.FnavchID = tfnavch.ID)
   INNER JOIN tfakultet ON (tgroups.FakultetId = tfakultet.ID)
   LEFT JOIN tnkp ON (tgroups.NkpID=tnkp.ID)
   LEFT JOIN
   (SELECT GROUP_CONCAT( tgroups.Name) AS PotokLec,tpredmets.PotokID FROM
   tpredmets
   INNER JOIN tgroups ON (tpredmets.GroupID = tgroups.ID)
   WHERE tpredmets.PotokID IS NOT NULL
   GROUP BY tpredmets.PotokID
   ) AS a ON (tpredmets.PotokID=a.potokid) AND (trozklad.Type=1)
   LEFT JOIN
   (SELECT GROUP_CONCAT( tgroups.Name) AS PotokPr,tpredmets.PotokPrID
   FROM tpredmets
   INNER JOIN tgroups ON (tpredmets.GroupID = tgroups.ID)
   WHERE tpredmets.PotokPrID IS NOT NULL
   GROUP BY tpredmets.PotokPrID
   ) AS a1 ON (tpredmets.PotokPrID=a1.potokPrid) AND (trozklad.Type=2)
   LEFT JOIN
   (SELECT GROUP_CONCAT( tgroups.Name) AS PotokLab,tpredmets.PotokLabID
   FROM tpredmets
   INNER JOIN tgroups ON (tpredmets.GroupID = tgroups.ID)
   WHERE tpredmets.PotokLabID IS NOT NULL
   GROUP BY tpredmets.PotokLabID
   ) AS a2 ON (tpredmets.PotokLabID=a2.potokLabid) AND (trozklad.Type=3)

LEFT JOIN
(
SELECT
CONCAT(IFNULL(tposada.Name,''),' - ',IFNULL(tposada.Stupin,'')) AS
Posada
,tposadainfo.kafedraid
,tposadainfo.loginid
FROM
tposadainfo
LEFT JOIN tposada
ON (tposadainfo.PosadaID = tposada.ID)
GROUP BY tposadainfo.kafedraid
,tposadainfo.loginid
) AS a3 ON (tpredmets.kafedraid=a3.kafedraid AND
tpredmetsinfo.loginid=a3.loginid )
WHERE tgroups.Rik=iRik AND trozpodil.noRoz=0
ORDER BY piv, trozklad.T, tgroups.Name,trozklad.Den , trozklad.Para
;
END$$

DELIMITER ;

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