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Amélioration perfo.

Amélioration des performances à l'aide de la dénormalisation

QuestionAnswer
Définir Normalisation Design logique structuré et cohérent pour éviter la redondance
Problème avec une base de données normalisé Pas efficace au niveau des performances, à cause des jointures
But de la dénormalisation Accepter une redondance contrôlée pour améliorer les performances
Désavantages de la dénormalisation (3) -Rend implémentation plus complexe -Sacrifice de souplesse -Améliore la recherche, mais ralenti les MAJ
Quoi prendre en considération lors de la dénormalisation -Réétudier les choix d'index -Faire des triggers pour l'intégrité des données -Vérifier la cohérence
Comment la dénormalisation améliore les performances(5) -calcul préalable des données dérivées -réduction des jointures -réduction des FK -réduction du nombre d'index -réduction du nombre de tables
Types de dénormalisations -Combiner association 1:1 -1:*(Pour les tables qui ne changent pas souvent)Utilisation de Trigger -1:* Dupliquer les attributs clés étrangères pour réduire les jointures -*:*Dupliquer les attributs pour réduire les jointures -Introduire un groupe rép.
tables d'extraction Jointure multi-relations, données relativement statiques
Partitionner des relations Pour gérer de très vastes relations. Il en existe 2 types : horizontal, vertical
3 solutions pour pallier aux problèmes de la dénormalisations -Déclencheur -Transaction -Réconciliation par lots
Created by: Gabswim
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