讲解：candidate key、R、ACID、RSPSS| Statistics、、

1)Given relation R(A,B,C,D,E)with functional dependencies{AB→C,C→D,D→E}.a.Show how to determine the candidate keyb.What is the reason that R is not BCNF?c.Show ALL steps needed to decompose R into BCNF relations,if possible.2)Many of the No-SQL systems that support large-scale parallel execution guarantee“eventual consistency”rather than the ACID properties.What does this mean? Explainbriefly how this can produce different results compared to a parallel SQL system thatguarantees the ACID properties.3)Consider the seschedules involving 3 transactions:S1:r1(x);r2(y);r1(z);r3(z);r2(x);r1(y)S2:r1(x);w2(y);r1(z);r3(z);w2(x);r1(y)S3:r1(x);w2(y);r1(z);r3(z);w1(x);r2(y)S4:r1(x);r2(y);r1(z);r3(z);w1(x);w2(y)For each schedule,draw the precedencegraph and decide if the schedule isconflict-serializable.4)Given three simple tables with FDsA→ B,B→ C,C→ DCreate tablet 1(ainteger,binteger);Create tablet 2(binteger,cinteger);Create tablet 3(cinteger,dinteger);data is provided in 3 CSV files for importing,or 3 SQL“insert”filesa.create the tables a代做candidate key作业、代写R编程作业、代做ACID留学生作业、R语言作业代写 代做SPSS|代写留学生 Ss defined above and import the data (10Krows)usingLOAD DATA(or equivalent).SQL insert statements are provided as an alternative.Consider these three different but equivalent queries.--1select a fromt 1where mod(a,5)=0 and bin(select b fromt 2where cin(SELECT c FROM t3 where mod(d,5)=0));--2select t1.a from t1,t2,t 3wheret1.b=t2.b and t2.c=t3.c and mod(t1.a,5)=0 and mod(t3.d,5)=0;--3select t1.a from(t1 join t2 on t1.b=t2.b)join t3 on t2.c=t3.cwhere mod(t1.a,5)=0 and mod(t3.d,5)=0;b.Which one of the above select statements has the best executionHmwk7,page2performance? Explain your decision,supported by facts,not just opinion.5)Consider an internet voting system where a voter must enter a PIN which is checkedto ensure it isvalid and not already used.Two tables are used:PIN(number,if_voted)and VOTES(can didate,count).Consider anewread-only transaction that outputs theentire vote tally table.Discuss the issues involved in selecting the appropriate isolation level to ensure correctly reporting the voting results.For example:转自：http://ass.3daixie.com/2018120110863785.html