复杂的SQL子查询失败

Question

所以最初这个查询正在使8 minutes返回1400行。我注释掉原始查询中导致滞后的部分。 EXPLAIN sql显示lien_objet_contact table没有索引。我不能简单地创建一个索引，因为这是为了工作而需要迁移。我相信如果我可以编写带有 TXT_POSTE_CONTACT 作为子查询的查询，我可以加快速度。

以下方法的问题在于它引入了所有联系人。我只想要基于下面的 WHERE 子句的联系人。所以他们必须附加到poste.strreference。基本上这是一个充满工作和候选人的数据库。每个工作都有一个联系人，您可以称之为招聘经理。我认为这更像是一个方法问题。我可能完全不在下面的尝试。如果是这样，我愿意接受建议。提前致谢。

 SELECT DISTINCT poste.pkposte 
                AS 
                `COLONNE_NON_AFFICHEE`, 
                poste.strreference 
                AS `TXT_REFERENCE`, 
                lib_poste.strlangue1 
                AS `TXT_INTITULE`, 
                Group_concat(DISTINCT Concat(lib_u.strprenom, ' ', 
                lib_u.strnom))             AS 
                `TXT_POSTE_CHARGE_RECRUTEMENT`,
                (SELECT Group_concat(DISTINCT Concat(lib_contact.strprenom, ' ', lib_contact.strnom)) 
                  FROM poste p
                   LEFT JOIN lien_objet_contact lib_loc
                   ON p.pkposte = lib_loc.fkobjet
                   LEFT JOIN contact lib_contact 
                   ON lib_loc.fkcontact = lib_contact.pkcontact) AS  `TXT_POSTE_CONTACT`,
                -- Group_concat(DISTINCT Concat(lib_contact.strprenom, ' ', 
                -- lib_contact.strnom)) AS 
                -- `TXT_POSTE_CONTACT`, 
                lib_country.strlangue1 
                AS `TXT_PAYS`, 
                lib_state.strlangue1 
                AS `TXT_REGION`, 
                lib_city.strlangue1 
                AS `TXT_DEPARTEMENT_GEO`, 
                Concat(c.strprenom, ' ', c.strnom) 
                AS `Candidate`, 
                CASE 
                  WHEN c.imobiliteinterne = 1 THEN "yes" 
                  WHEN c.imobiliteinterne = 0 THEN "no" 
                end 
                AS `Internal_Candidate`, 
                Max(Date_format(sa_hired_date.dtdateaction, "%c/%e/%y")) 
                AS `TXT_EMBAUCHER`, 
                Date_format(hireInfo.dtdebut, "%c/%e/%y") 
                AS StartDate, 
                Source.strlangue1 
                AS TXT_PARTENAIRE_SOURCE 
FROM   poste 
       INNER JOIN r_texte_court lib_poste 
               ON poste.fklibintitule = lib_poste.pktextecourt 
       LEFT JOIN lien_utilisateur_objet lib_luo 
              ON poste.pkposte = lib_luo.fkobjet 
                 AND lib_luo.itypeobjet = 2 
       LEFT JOIN utilisateur lib_u 
              ON lib_luo.fkutilisateur = lib_u.pkutilisateur 
       -- LEFT JOIN lien_objet_contact lib_loc 
       --        ON poste.pkposte = lib_loc.fkobjet 
       --           AND lib_loc.itypeobjet = 2 
       --           AND lib_loc.strcontexte = 'descriptif/contact' 
       -- LEFT JOIN contact lib_contact 
       --        ON lib_loc.fkcontact = lib_contact.pkcontact 
       LEFT JOIN affectation aff 
              ON aff.fkposte = poste.pkposte 
                 AND aff.isuppr = 0 
       LEFT JOIN candidat c 
              ON c.pkcandidat = aff.fkcandidat 
       LEFT JOIN lien_objet_ref_1 lor1a 
              ON lor1a.fkobjet = poste.pkposte 
                 AND lor1a.itypeobjet = 2 
                 AND lor1a.strcontexte = 'descriptif/pays' 
       LEFT JOIN r_referentiel rr_country 
              ON lor1a.fkreferentiel = rr_country.pkreferentiel 
       LEFT JOIN r_libelle_ref lib_country 
              ON rr_country.fklib1 = lib_country.pklibelleref 
       LEFT JOIN lien_objet_ref_2 lor2a 
              ON lor2a.fkobjet = poste.pkposte 
                 AND lor2a.itypeobjet = 2 
                 AND lor2a.strcontexte = 'descriptif/region' 
       LEFT JOIN r_referentiel rr_state 
              ON lor2a.fkreferentiel = rr_state.pkreferentiel 
       LEFT JOIN r_libelle_ref lib_state 
              ON rr_state.fklib1 = lib_state.pklibelleref 
       LEFT JOIN lien_objet_ref_3 lor3a 
              ON lor3a.fkobjet = poste.pkposte 
                 AND lor3a.itypeobjet = 2 
                 AND lor3a.strcontexte = 'descriptif/departement_geo' 
       LEFT JOIN r_referentiel rr_city 
              ON lor3a.fkreferentiel = rr_city.pkreferentiel 
       LEFT JOIN r_libelle_ref lib_city 
              ON rr_city.fklib1 = lib_city.pklibelleref 
       LEFT JOIN historique_candidat sa_hired_date 
              ON c.pkcandidat = sa_hired_date.fkcandidat 
       LEFT JOIN embauche hireInfo 
              ON aff.pkaffectation = hireInfo.fkaffectation 
       INNER JOIN embauche hireInfoFilter 
               ON aff.pkaffectation = hireInfoFilter.fkaffectation 
       LEFT JOIN candidature cand 
              ON c.pkcandidat = cand.fkcandidat 
       LEFT JOIN partenaire pnaire 
              ON cand.fkpartenairesource = pnaire.pkpartenaire 
       LEFT JOIN r_texte_court Source 
              ON Source.pktextecourt = pnaire.fklibnom 
WHERE  poste.isuppr <> 1 
       AND poste.pkposte <> 1 
       AND hireInfo.iembauche = 1 
GROUP  BY `txt_reference`, 
          `pkcandidat`