133 lines
3.1 KiB
SQL
133 lines
3.1 KiB
SQL
--Exercice 1
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CREATE INDEX ix_cl ON CLIENT(id);
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/*
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impossible d'inserer cet index parce que id est la clef primaire.
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et les clef primaire ont deja un index
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*/
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--Exercice 2
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SET AUTOTRACE ON
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SELECT * FROM LIGNE_COMMANDE WHERE COMMANDE_ID=46;
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--observation
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CREATE INDEX ix_commande_id ON LIGNE_COMMANDE (COMMANDE_ID,
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PRODUIT_ID) ;
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SET AUTOTRACE ON
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SELECT * FROM LIGNE_COMMANDE WHERE COMMANDE_ID=46;
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--observation: l'index est sur la colonne COMMANDE_ID donc c'est beaucoup plus efficace
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SELECT PRODUIT_ID FROM LIGNE_COMMANDE WHERE
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COMMANDE_ID = 46;
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--observation: l'index est sur la colonne COMMANDE_ID et PRODUIT_ID donc c'est beaucoup plus efficace
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DROP INDEX ix_commande_id;
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--Exercice 3
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SELECT cl.nom, SUM(lc.prix_total)
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FROM CLIENT cl
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INNER JOIN COMMANDE c ON c.client_id = cl.id
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INNER JOIN LIGNE_COMMANDE lc ON lc.commande_id = c.id
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GROUP BY cl.nom;
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SELECT cl.nom, SUM(lc.prix_total) FROM CLIENT cl INNER JOIN COMMANDE c ON c.client_id = cl.id INNER JOIN LIGNE_COMMANDE lc ON lc.commande_id = c.id GROUP BY cl.nom;
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--on utilise ici des hash join pour les jointures.
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--les tables sont lu integralement
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CREATE index test1 on COMMANDE(client_id);
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CREATE index test2 on LIGNE_COMMANDE(commande_id);
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DROP INDEX test1;
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DROP INDEX test2;
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--Exercice 4
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SELECT * FROM LIGNE_COMMANDE WHERE PRODUIT_ID IN (SELECT ID FROM PRODUIT WHERE PRIX_UNITAIRE>100);
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SELECT L.* FROM LIGNE_COMMANDE L JOIN PRODUIT P ON (L.PRODUIT_ID=P.ID) WHERE P.PRIX_UNITAIRE>100;
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--parreille 13 de cout et 46 de consistents get
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SELECT * FROM LIGNE_COMMANDE lc WHERE EXISTS (SELECT * FROM PRODUIT p WHERE p.id=lc.produit_id AND p.prix_unitaire > 100);
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-- 93 consistent gets
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--il doit y avoir une erreur quelque part. Mais voici du plus efficace au moins efficace:
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-- 1) EXISTS / NOT EXISTS
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-- 2) JOIN ON
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-- 3) WHERE IN
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--Exercice 5
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CREATE TABLE BIGBITMAP(
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id NUMBER PRIMARY KEY,
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nbitmap NUMBER,
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date_insertion DATE
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);
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BEGIN
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for id in 0..300000 LOOP
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INSERT INTO BIGBITMAP VALUES
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( id,
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MOD(id,5) ,
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TO_DATE(sysdate, 'DD/MM/YYYY')
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);
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Commit;
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END LOOP;
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dbms_output.put_line ('100000 lignes inserees');
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END;
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CREATE INDEX ix_nbitmap_tree ON BIGBITMAP (nbitmap);
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DROP INDEX ix_nbitmap_tree;
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CREATE BITMAP INDEX ix_nbitmap_bitmap ON BIGBITMAP (nbitmap);
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DROP INDEX ix_nbitmap_bitmap;
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/*
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218 recursive calls
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0 db block gets
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3741 consistent gets
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1568 physical reads
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0 redo size
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335 bytes sent via SQL*Net to client
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41 bytes received via SQL*Net from client
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2 SQL*Net roundtrips to/from client
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5 sorts (memory)
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0 sorts (disk)
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1 rows processed
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*/
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/*
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0 recursive calls
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0 db block gets
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2558 consistent gets
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0 physical reads
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0 redo size
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335 bytes sent via SQL*Net to client
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41 bytes received via SQL*Net from client
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2 SQL*Net roundtrips to/from client
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0 sorts (memory)
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0 sorts (disk)
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1 rows processed
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*/
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/*
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52 recursive calls
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0 db block gets
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127 consistent gets
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35 physical reads
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0 redo size
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335 bytes sent via SQL*Net to client
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41 bytes received via SQL*Net from client
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2 SQL*Net roundtrips to/from client
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0 sorts (memory)
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0 sorts (disk)
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1 rows processed
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*/ |