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Session 6: Workload optimization
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‎Laboratori/Sessió 6.txt

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Ex. 1
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Donades les taules i les dades al fitxer adjunt, feu el disseny físic de la base de dades de manera que sigui òptima l'execució de les comandes següents (la freqüencia d'execució de cadascuna està indicada entre parèntesis):
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(10%) SELECT * FROM empleats e WHERE sou BETWEEN 15000 AND 20000;
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(42%) SELECT * FROM departaments d WHERE seu = 1;
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(05%) SELECT * FROM (
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SELECT * FROM empleats e WHERE id = 1 union all
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SELECT * FROM empleats e WHERE id = 10 union all
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SELECT * FROM empleats e WHERE id = 100 union all
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SELECT * FROM empleats e WHERE id = 1000 union all
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SELECT * FROM empleats e WHERE id = 10000);
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(43%) SELECT * FROM departaments d, seus s WHERE s.id = d.seu AND s.id > 9;
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Tingueu en compte que només podeu utilitzar 1370 blocs d'espai en total.
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Fitxer adjunt:
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CREATE TABLE seus (
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id INTEGER,
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ciutat CHAR(40)
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) PCTFREE 0 ENABLE ROW MOVEMENT;
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-- Id és clau candidata
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CREATE TABLE empleats (
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id INTEGER,
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nom CHAR(200),
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sou INTEGER,
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edat INTEGER,
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dpt INTEGER,
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historial CHAR(500)
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) PCTFREE 0 ENABLE ROW MOVEMENT;
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-- Id és clau candidata
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CREATE TABLE departaments (
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id INTEGER,
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nom CHAR(200),
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seu INTEGER,
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tasques CHAR(2000)
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) PCTFREE 0 ENABLE ROW MOVEMENT;
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-- Id és clau candidata
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DECLARE
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i INTEGER;
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BEGIN
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DBMS_RANDOM.seed(0);
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-- Insercions de seus
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INSERT INTO seus (id, ciutat) VALUES (1, 'BARCELONA');
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INSERT INTO seus (id, ciutat) VALUES (2, 'GIRONA');
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INSERT INTO seus (id, ciutat) VALUES (3, 'ZARAGOZA');
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INSERT INTO seus (id, ciutat) VALUES (4, 'MADRID');
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INSERT INTO seus (id, ciutat) VALUES (5, 'GRANADA');
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INSERT INTO seus (id, ciutat) VALUES (6, 'PARIS');
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INSERT INTO seus (id, ciutat) VALUES (7, 'LONDRES');
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INSERT INTO seus (id, ciutat) VALUES (8, 'FRANKFURT');
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INSERT INTO seus (id, ciutat) VALUES (9, 'LIMA');
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INSERT INTO seus (id, ciutat) VALUES (10, 'TOKIO');
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-- Insercions de departaments
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FOR i IN 1..1100 LOOP
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INSERT INTO departaments (id, nom, seu, tasques) VALUES (i,
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LPAD(dbms_random.string('U',10),200,'*'),
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dbms_random.value(1,10),
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LPAD(dbms_random.string('U',10),2000,'*')
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);
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END LOOP;
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-- Insercions d'empleats
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FOR i IN 1..(10000) LOOP
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INSERT INTO empleats (id, nom, sou, edat, dpt, historial) VALUES (
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i,
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LPAD(dbms_random.string('U',10),200,'*'),
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dbms_random.value(15000,50000),
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dbms_random.value(19,64),
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dbms_random.value(1,1100),
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LPAD(dbms_random.string('U',10),500,'*')
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);
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END LOOP;
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END;
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ALTER TABLE empleats SHRINK SPACE;
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ALTER TABLE departaments SHRINK SPACE;
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ALTER TABLE seus SHRINK SPACE;
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---------------------------- Update Statistics -----------------------------
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DECLARE
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esquema VARCHAR2(100);
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CURSOR c IS SELECT TABLE_NAME FROM USER_TABLES;
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BEGIN
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SELECT '"'||sys_context('USERENV', 'CURRENT_SCHEMA')||'"' INTO esquema FROM dual;
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FOR taula IN c LOOP
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DBMS_STATS.GATHER_TABLE_STATS(
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ownname => esquema,
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tabname => taula.table_name,
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estimate_percent => NULL,
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method_opt =>'FOR ALL COLUMNS SIZE REPEAT',
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granularity => 'GLOBAL',
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cascade => TRUE
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);
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END LOOP;
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END;
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---------------------------- To check the real costs -------------------------
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CREATE TABLE measure (id INTEGER, weight FLOAT, i FLOAT, f FLOAT);
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DECLARE
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i0 INTEGER;
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i1 INTEGER;
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i2 INTEGER;
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i3 INTEGER;
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i4 INTEGER;
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r INTEGER;
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BEGIN
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select value INTO i0
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from v$statname c, v$sesstat a
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where a.statistic# = c.statistic#
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and sys_context('USERENV','SID') = a.sid
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and c.name in ('consistent gets');
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SELECT MAX(LENGTH(e.id||e.nom||e.sou||e.edat||e.dpt||e.historial)) INTO r FROM empleats e WHERE sou BETWEEN 15000 AND 20000;
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select value INTO i1
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from v$statname c, v$sesstat a
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where a.statistic# = c.statistic#
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and sys_context('USERENV','SID') = a.sid
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and c.name in ('consistent gets');
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SELECT MAX(LENGTH(d.id||d.nom||d.seu||d.tasques)) INTO r FROM departaments d WHERE seu = 1;
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select value INTO i2
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from v$statname c, v$sesstat a
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where a.statistic# = c.statistic#
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and sys_context('USERENV','SID') = a.sid
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and c.name in ('consistent gets');
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SELECT MAX(LENGTH(e.id||e.nom||e.sou||e.edat||e.dpt||e.historial)) INTO r FROM (
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SELECT * FROM empleats e WHERE id = 1 union all
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SELECT * FROM empleats e WHERE id = 10 union all
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SELECT * FROM empleats e WHERE id = 100 union all
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SELECT * FROM empleats e WHERE id = 1000 union all
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SELECT * FROM empleats e WHERE id = 10000) e;
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select value INTO i3
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from v$statname c, v$sesstat a
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where a.statistic# = c.statistic#
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and sys_context('USERENV','SID') = a.sid
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and c.name in ('consistent gets');
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SELECT MAX(LENGTH(d.id||d.nom||d.seu||d.tasques||s.id||s.ciutat)) INTO r FROM departaments d, seus s WHERE s.id = d.seu AND s.id > 9;
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select value INTO i4
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from v$statname c, v$sesstat a
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where a.statistic# = c.statistic#
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and sys_context('USERENV','SID') = a.sid
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and c.name in ('consistent gets');
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INSERT INTO measure (id,weight,i,f) VALUES (1,0.10,i0,i1);
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INSERT INTO measure (id,weight,i,f) VALUES (2,0.42,i1,i2);
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INSERT INTO measure (id,weight,i,f) VALUES (3,0.05,i2,i3);
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INSERT INTO measure (id,weight,i,f) VALUES (4,0.43,i3,i4);
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END;
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SELECT SUM((f-i)*weight) FROM measure;
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DROP TABLE measure PURGE;
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Solució:
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Bitmap sobre l'atribut seu a la taula departaments
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B+ sobre l'atribut id a la taula empleats

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