how to avoid sub-query to gain performance - sql

Question

i have a reporting query which have 2 long sub-query
SELECT r1.code_centre, r1.libelle_centre, r1.id_equipe, r1.equipe, r1.id_file_attente,
r1.libelle_file_attente,r1.id_date, r1.tranche, r1.id_granularite_de_periode,r1.granularite,
r1.ContactsTraites, r1.ContactsenParcage, r1.ContactsenComm, r1.DureeTraitementContacts,
r1.DureeComm, r1.DureeParcage, r2.AgentsConnectes, r2.DureeConnexion, r2.DureeTraitementAgents,
r2.DureePostTraitement
FROM
( SELECT cc.id_centre_contact, cc.code_centre, cc.libelle_centre, a.id_equipe, a.equipe,
a.id_file_attente, f.libelle_file_attente, a.id_date, g.tranche, g.id_granularite_de_periode,
g.granularite, sum(Nb_Contacts_Traites) as ContactsTraites,
sum(Nb_Contacts_en_Parcage) as ContactsenParcage,
sum(Nb_Contacts_en_Communication) as ContactsenComm,
sum(Duree_Traitement/1000) as DureeTraitementContacts,
sum(Duree_Communication / 1000 + Duree_Conference / 1000 + Duree_Com_Interagent / 1000) as DureeComm,
sum(Duree_Parcage/1000) as DureeParcage
FROM agr_synthese_activite_media_fa_agent a, centre_contact cc,
direction_contact dc, granularite_de_periode g, media m, file_attente f
WHERE m.id_media = a.id_media
AND cc.id_centre_contact = a.id_centre_contact
AND a.id_direction_contact = dc.id_direction_contact
AND dc.direction_contact ='INCOMING'
AND a.id_file_attente = f.id_file_attente
AND m.media = 'PHONE'
AND ( ( g.valeur_min = date_format(a.id_date,'%d/%m') and g.granularite = 'Jour')
or ( g.granularite = 'Heure' and a.id_th_heure = g.id_granularite_de_periode) )
GROUP by cc.id_centre_contact, a.id_equipe, a.id_file_attente, a.id_date, g.tranche,
g.id_granularite_de_periode) r1,
(
(SELECT cc.id_centre_contact,cc.code_centre, cc.libelle_centre, a.id_equipe, a.equipe,
a.id_date, g.tranche, g.id_granularite_de_periode,g.granularite,
count(distinct a.id_agent) as AgentsConnectes,
sum(Duree_Connexion / 1000) as DureeConnexion,
sum(Duree_en_Traitement / 1000) as DureeTraitementAgents,
sum(Duree_en_PostTraitement / 1000) as DureePostTraitement
FROM activite_agent a, centre_contact cc, granularite_de_periode g
WHERE ( g.valeur_min = date_format(a.id_date,'%d/%m') and g.granularite = 'Jour')
AND cc.id_centre_contact = a.id_centre_contact
GROUP BY cc.id_centre_contact, a.id_equipe, a.id_date, g.tranche, g.id_granularite_de_periode )
UNION
(SELECT cc.id_centre_contact,cc.code_centre, cc.libelle_centre, a.id_equipe, a.equipe,
a.id_date, g.tranche, g.id_granularite_de_periode,g.granularite,
count(distinct a.id_agent) as AgentsConnectes,
sum(Duree_Connexion / 1000) as DureeConnexion,
sum(Duree_en_Traitement / 1000) as DureeTraitementAgents,
sum(Duree_en_PostTraitement / 1000) as DureePostTraitement
FROM activite_agent a, centre_contact cc, granularite_de_periode g
WHERE ( g.granularite = 'Heure'
AND a.id_th_heure = g.id_granularite_de_periode)
AND cc.id_centre_contact = a.id_centre_contact
GROUP BY cc.id_centre_contact,a.id_equipe, a.id_date, g.tranche, g.id_granularite_de_periode)
) r2
WHERE r1.id_centre_contact = r2.id_centre_contact
AND r1.id_equipe = r2.id_equipe AND r1.id_date = r2.id_date
AND r1.tranche = r2.tranche AND r1.id_granularite_de_periode = r2.id_granularite_de_periode
GROUP BY r1.id_centre_contact , r1.id_equipe, r1.id_file_attente,
r1.id_date, r1.tranche, r1.id_granularite_de_periode
ORDER BY r1.code_centre, r1.libelle_centre, r1.equipe,
r1.libelle_file_attente, r1.id_date, r1.id_granularite_de_periode,r1.tranche
the EXPLAIN shows
| id | select_type | table | type| possible_keys | key | key_len | ref| rows | Extra |
'1', 'PRIMARY', '<derived3>', 'ALL', NULL, NULL, NULL, NULL, '2520', 'Using temporary; Using filesort'
'1', 'PRIMARY', '<derived2>', 'ALL', NULL, NULL, NULL, NULL, '4378', 'Using where; Using join buffer'
'3', 'DERIVED', 'a', 'ALL', 'fk_Activite_Agent_centre_contact', NULL, NULL, NULL, '83433', 'Using temporary; Using filesort'
'3', 'DERIVED', 'g', 'ref', 'Index_granularite,Index_Valeur_min', 'Index_Valeur_min', '23', 'func', '1', 'Using where'
'3', 'DERIVED', 'cc', 'ALL', 'PRIMARY', NULL, NULL, NULL, '6', 'Using where; Using join buffer'
'4', 'UNION', 'g', 'ref', 'PRIMARY,Index_granularite', 'Index_granularite', '23', '', '24', 'Using where; Using temporary; Using filesort'
'4', 'UNION', 'a', 'ref', 'fk_Activite_Agent_centre_contact,fk_activite_agent_TH_heure', 'fk_activite_agent_TH_heure', '5', 'reporting_acd.g.Id_Granularite_de_periode', '2979', 'Using where'
'4', 'UNION', 'cc', 'ALL', 'PRIMARY', NULL, NULL, NULL, '6', 'Using where; Using join buffer'
NULL, 'UNION RESULT', '<union3,4>', 'ALL', NULL, NULL, NULL, NULL, NULL, ''
'2', 'DERIVED', 'g', 'range', 'PRIMARY,Index_granularite,Index_Valeur_min', 'Index_granularite', '23', NULL, '389', 'Using where; Using temporary; Using filesort'
'2', 'DERIVED', 'a', 'ALL', 'fk_agr_synthese_activite_media_fa_agent_centre_contact,fk_agr_synthese_activite_media_fa_agent_direction_contact,fk_agr_synthese_activite_media_fa_agent_file_attente,fk_agr_synthese_activite_media_fa_agent_media,fk_agr_synthese_activite_media_fa_agent_th_heure', NULL, NULL, NULL, '20903', 'Using where; Using join buffer'
'2', 'DERIVED', 'cc', 'eq_ref', 'PRIMARY', 'PRIMARY', '4', 'reporting_acd.a.Id_Centre_Contact', '1', ''
'2', 'DERIVED', 'f', 'eq_ref', 'PRIMARY', 'PRIMARY', '4', 'reporting_acd.a.Id_File_Attente', '1', ''
'2', 'DERIVED', 'dc', 'eq_ref', 'PRIMARY', 'PRIMARY', '4', 'reporting_acd.a.Id_Direction_Contact', '1', 'Using where'
'2', 'DERIVED', 'm', 'eq_ref', 'PRIMARY', 'PRIMARY', '4', 'reporting_acd.a.Id_Media', '1', 'Using where'
don't know it very clear, but i think is the problem of seems it take full scaning
than i change all the sub-query to views(create view as select sub-query), and the result is the same
thanks for any advice

Answer 1

Subquery and view will most of the time give you same result speed-wise.
If your subquery is not variabe, consider creating table that has same structure as your view, and occasionally do:
truncate table my_table;
insert into my_table select * from my_view;
...to cache your subquery data. If properly indexed, it will marginalize time lost on storing results of subquery in table, if data is not that frequently changed, or at least if you don't need up-to-date information on second-to-second basis.