25. 均一にすべてのストレージに分散
ランダムに分散
指定されたキーのハッシュ値で分散
同じキーは同じストレージに分散
Id User Tran
123 Bob 3000
324 Sue 110
324 Sue 40000
45 George 60
154 Sally 990
123 Bob 230
Id User Tran
123 Bob 3000
324 Sue 110
324 Sue 40000
45 George 60
154 Sally 990
123 Bob 230
ハッシュ関数
Dist1 Dist2 Dist3 Dist4Dist1 Dist2 Dist3 Dist4
27. LINEITEM HASH( [PARTKEY] )
[PARTKEY] NOTNULL INT
PART HASH( [PARTKEY] )
[PARTKEY] NOTNULL BIGINT
select sum( [EXTENDEDPRICE] ) from [LINEITEM],[PART]
where [PARTKEY] = [PARTKEY];
28. LINEITEM HASH( [PARTKEY] )
[PARTKEY] NOTNULL INT
PART HASH( [PARTKEY] )
[PARTKEY] NOTNULL INT
select sum( [EXTENDEDPRICE] ) from [LINEITEM],[PART]
where [PARTKEY] = [PARTKEY];