1. 09_Queries_LECTURE2
CODE GENERATION implements the operator, JOIN (equi-join, we will use  for it.)
J1. NESTED LOOP
JOIN S on S.S#=E.S#
For each record in S, (the outer loop over records from the outer or driver relation),
retrieve every record from E, (the inner loops over the inner relation),
test join condition,
if it's true, concatenate the tuples (project off unwanted columns) and output,
else go to next E (inner-relation) record.
SELECT SNAME,C#,GRADE FROM S=STUDENT,E=ENROLL WHERE S.S#=E.S#;
S#|SNAME |LCODE
25|CLAY |NJ5101
32|THAISZ|NJ5102
38|GOOD |FL6321
17|BAID |NY2091
57|BROWN |NY2092 S
S#|C#|GR
32|8 |89
32|7 |91
25|7 |68
25|6 |76
32|6 |62 E
SNAME |C# |GRADE
Result
CLAY | 7 | 68
S.S#=E.S#
FALSE
CLAY | 6 | 76
S.S#=E.S#
FALSE
S.S#=E.S#
TRUE
S.S#=E.S#
TRUE
S.S#=E.S#
FALSE
Section 9 # 19 11

2. CODE GENERATION implements the operator, JOIN (equi-join, we will use  for it.)
J1. NESTED LOOP
Second inner loop pass:
SELECT SNAME,C#,GRADE FROM S=STUDENT,E=ENROLL WHERE S.S#=E.S#;
S#|SNAME |LCODE
25|CLAY |NJ5101
32|THAISZ|NJ5102
38|GOOD |FL6321
17|BAID |NY2091
57|BROWN |NY2092 S
S#|C#|GR
32|8 |89
32|7 |91
25|7 |68
25|6 |76
32|6 |62 E
SNAME |C# |GRADE
res
CLAY | 7 | 68
CLAY | 6 | 76
THAISZ| 8 | 89
S.S#=E.S
TRUE
THAISZ| 7 | 91
S.S#=E.S
TRUE
THAISZ| 6 | 62
S.S#=E.S#
FALSE
S.S#=E.S#
FALSE
S.S#=E.S#
TRUE
Section 9 # 20 11

3. CODE GENERATION implements the operator, JOIN (equi-join, we will use  for it.)
J1. NESTED LOOP
Third inner loop pass:
SELECT SNAME,C#,GRADE FROM S=STUDENT,E=ENROLL WHERE S.S#=E.S#;
S#|SNAME |LCODE
25|CLAY |NJ5101
32|THAISZ|NJ5102
38|GOOD |FL6321
17|BAID |NY2091
57|BROWN |NY2092 S
S#|C#|GR
32|8 |89
32|7 |91
25|7 |68
25|6 |76
32|6 |62 E
SNAME |C# |GRADE
res
CLAY | 7 | 68
CLAY | 6 | 76
THAISZ| 8 | 89
THAISZ| 7 | 91
S.S#=E.S
FALSE
THAISZ| 6 | 62
S.S#=E.S
FALSE
S.S#=E.S
FALSE
S.S#=E.S#
FALSE
S.S#=E.S#
FALSE
Section 9 # 21 11

4. CODE GENERATION implements the operator, JOIN (equi-join, we will use  for it.)
J1. NESTED LOOP
4th inner loop pass:
SELECT SNAME,C#,GRADE FROM S=STUDENT,E=ENROLL WHERE S.S#=E.S#;
S#|SNAME |LCODE
25|CLAY |NJ5101
32|THAISZ|NJ5102
38|GOOD |FL6321
17|BAID |NY2091
57|BROWN |NY2092 S
S#|C#|GR
32|8 |89
32|7 |91
25|7 |68
25|6 |76
32|6 |62 E
SNAME |C# |GRADE
res
CLAY | 7 | 68
CLAY | 6 | 76
THAISZ| 8 | 89
THAISZ| 7 | 91
S.S#=E.S
FALSE
THAISZ| 6 | 62
S.S#=E.S
FALSE
S.S#=E.S
FALSE
S.S#=E.S
FALSE
S.S#=E.S#
FALSE
Section 9 # 9 11

5. CODE GENERATION implements the operator, JOIN (equi-join, we will use  for it.)
J1. NESTED LOOP
R 5th and last inner loop pass:
SELECT SNAME,C#,GRADE FROM S=STUDENT,E=ENROLL WHERE S.S#=E.S#;
S#|SNAME |LCODE
25|CLAY |NJ5101
32|THAISZ|NJ5102
38|GOOD |FL6321
17|BAID |NY2091
57|BROWN |NY2092 S
S#|C#|GR
32|8 |89
32|7 |91
25|7 |68
25|6 |76
32|6 |62 E
SNAME |C# |GRADE
res
CLAY | 7 | 68
CLAY | 6 | 76
THAISZ| 8 | 89
THAISZ| 7 | 91
THAISZ| 6 | 62
S.S#=E.S#
FALSE
S.S#=E.S
FALSE
S.S#=E.S
FALSE
S.S#=E.S
FALSE
S.S#=E.S
FALSE
Section 9 # 23 11

6. CODE GENERATION implements the operator, JOIN (equi-join, we will use  for it.)
J2. When there is an Index on one join attribute the join can be done in one pass (called Indexed Nested Loop.
If there is an index on E.S#, get r in S, get matching E-tuples using the index (need not scan entire inner relation, E, each time as was necessary with J1) .
R=SELECT SNAME,C#,GRADE FROM S=STUDENT,E=ENROLL WHERE S.S#=E.S#;
SNAME |C# |GRADE R S E
S#|SNAME |LCODE
25|CLAY |NJ5101
32|THAISZ|NJ5102
38|GOOD |FL6321
17|BAID |NY2091
57|BROWN |NY2092
RRN|S#|C#|GR
0 |32|8 |89
1 |32|7 |91
2 |25|7 |68
3 |25|6 |76
4 |32|6 |62
CLAY | 7 | 68
CLAY | 6 | 76
THAISZ| 8 | 89
THAISZ| 7 | 91
THAISZ| 6 | 62
RRN |S#
2,3 |25
0,1,4|32
Dense Index on E.S#
Section 9 # 24 11

7. CODE GENERATION implements the operator, JOIN (equi-join, we will use  for it.)
J3. MERGE JOIN: If both S.S# and E.S# are clustered, then scan both S and E once in order, keeping in mind that S.S# is the primary key (uniqueness property), but E.S# is not.
R=SELECT SNAME,C#,GRADE FROM S=STUDENT,E=ENROLL WHERE S.S#=E.S#;
SNAME |C# |GRADE R S E
S#|SNAME |LCODE
17|BAID |NY2091
25|CLAY |NJ5101
32|THAISZ|NJ5102
38|GOOD |FL6321
57|BROWN |NY2092
S#|C#|GR
25|7 |68
25|6 |76
32|6 |62
32|8 |89
32|7 |91
CLAY | 7 | 68
S.S#=E.S#
FALSE
S.S#=E.S#
TRUE
CLAY | 6 | 76
S.S#=E.S#
TRUE
THAISZ| 6 | 62
S.S#=E.S#
FALSE
S.S#=E.S#
TRUE
THAISZ| 8 | 89
S.S#=E.S#
TRUE
S.S#=E.S#
TRUE
THAISZ| 7 | 91
S.S#=E.S#
FALSE
S.S#=E.S#
FALSE
J3'. SORT-MERGE JOIN: If R.A and S.B are not ordered, sort them first (into R' clustered on A and S' clustered on B), then apply MERGE (J2 above).
Section 9 # 25 11

8. CODE GENERATION implements the operator, JOIN
J4. HASH-JOIN: RIDs hashed to buckets (pages). Corresponding buckets retrieved and scanned
GRACE JOIN: (first example of a hash-join technique): Allocate M pages of memory to the join process. Partition the M page frames as follows: One page frame for new pages as they are read from disk (called that page frame, IN), then the remaining B+1 become hash buckets R0,..,RB ( Note: B = M-2 ). Use hash function, h(S#)=MODB(S#)
Partial Sort (Build) Phase:
Partially-Sort-S: Read each S-page to IN, hash each record using h(S#) to R0,...,RB. If the bucket, say Ri, is full (collision), flush it to temporary disk file named Si.
Partially-Sort-E: Read each E-page into IN, hash each record with h(S#). Upon collision in a bucket, say Rj, flush its' contents to a temporary disk file, named Ej.
Probe Phase: With each pair of temporary files, S0 & E0, S1 & E2, S2 & E2, ... in turn, do as follows: Re-partition memory with two page frames called IN and OUT. With the rest, form one large hash area. For Si, construct an internal a hash table in the hash area using another hash function, k(S#) FOR Ei, PROBE the hash table using k(S#) for matches, output the join of all matches to OUT.
Section 9 # 26 11

9. CODE GENERATION implements the operator, JOIN
J4. HASH-JOIN: RIDs hashed to buckets (pages). Matching buckets are retrieved and scanned.
R=SELECT SNAME,C#,GRADE FROM S=STUDENT,E=ENROLL WHERE S.S#=E.S#;
GRACE JOIN: (first example of a hash-join technique): Allocate M=4 pages of memory to the join process. Partition the M pages as follows: - One page for IN (putting new pages as they are read from disk), M-1=3 pages for buckets R0,..,R2. Build Phase.
Use hash function, h(S#)=MOD3(S#) S
RID|S#|SNAME | LCODE R0 R1 R2 IN
1,0|17|BAID |NY2091 S0
1,1|25|CLAY |NJ5101
57|BROWN |NY2092
2,0|32|THAISZ|NJ5102
2,1|57|BROWN |NY2092 S1
3,0|38|GOOD |FL6321
25|CLAY |NJ5101
3,0|38|GOOD |FL6321
2,0|32|THAISZ|NJ5102
1,0|17|BAID |NY2091
1,1|25|CLAY |NJ5101
2,1|57|BROWN |NY2092 S2
17|BAID |NY2091 E
Collision! Dump R2 Then flush all.
32|THAISZ|NJ5102
RID|S#|C#|GR| LCODE
Do the same with E.
38|GOOD |FL6321
1,0|17|5 |96|NJ5101 E0
1,1|25|7 |68|ND4456
Partial-Sort-S:
Read each S-page to IN, hash
each record using h(S#) to R0,R1,R2.
Upon collision in any of the buckets,
flush to temporary disk file,
called S0,S1,S2.
2,0|25|6 |76|NY2091 E1
2,1|32|8 |89|NY2091
25|7 |68|ND4456
3,0|32|7 |91|FL6320
25|6 |76|NY2091
3,1|34|6 |62|ND4456
34|6 |62|ND4456 E2
17|5 |96|NJ5101
32|8 |89|NY2091
32|7 |91|FL6320
Section 9 # 27 11

10. CODE GENERATION implements the operator, GRACE JOIN
Hash Phase: With each pair of temporary files, S0 & E0, S1 & E2, S2 & E2,... in turn, do as follows:
Re-partition memory into IN, OUT and one large hash area.
Probe Phase: For Si, BUILD internal a hash table in the hash area using another hash function, k(S#)=MOD4
(open addr for collisions)
FOR Ei, PROBE hash table using k for matches,
output join of matches to OUT.
Start with S0 and E0. But E0 empty (no output will be produced) so skip.
PROBE S1 and E1: 1. Read S1 page-1 to IN. 2. Hash IN to HASH. S0
57|BROWN |NY2092 S1
25|CLAY |NJ5101 S2
17|BAID |NY2091
32|THAISZ|NJ5102
38|GOOD |FL6321 E0
OUT IN 1 2 3
Hash E1
25|7 |68|ND4456
25|CLAY |NJ5101
25|6 |76|NY2091
34|6 |62|ND4456 E2
17|5 |96|NJ5101
25|CLAY |NJ5101
32|8 |89|NY2091
32|7 |91|FL6320
Section 9 # 28 11

11. CODE GENERATION implements GRACE JOIN
PROBE S1, E1: 1. Read S1 page-1 to IN. 2. Hash IN to HASH Read E1 to IN 4. Concatenate to OUT. S0
57|BROWN |NY2092 S1
25|CLAY |NJ5101 S2
17|BAID |NY2091
32|THAISZ|NJ5102
38|GOOD |FL6321 E0
CLAY|7 |68
OUT IN 1 2 3
Hash
CLAY|6 |76 E1
25|7 |68|ND4456
25|CLAY |NJ5101
25|6 |76|NY2091
34|6 |62|ND4456 E2
17|5 |96|NJ5101
25|7 |68|ND4456
32|8 |89|NY2091
25|6 |76|NY2091
32|7 |91|FL6320
Section 9 # 29 11

12. CODE GENERATION implements GRACE JOIN
PROBE S1, E1: 1. Read S1 pg1 to IN. 2. Hash IN to HASH. 3. Read E1 to IN 4. Concatenate to OUT.
5. Read (next page of) E1 to IN. 6. Hash to HASH.
7. If match, Concatenate to OUT (Since OUT is full, flush OUT first.). But no match!
8. Flush HASH and IN when done with S1, E1 Probe (before starting Probe S2, E2). S0
57|BROWN |NY2092 S1
25|CLAY |NJ5101 S2
17|BAID |NY2091
32|THAISZ|NJ5102
38|GOOD |FL6321 E0
CLAY|7 |68
OUT IN 1 2 3
Hash
CLAY|6 |76 E1
25|7 |68|ND4456
25|CLAY |NJ5101
25|6 |76|NY2091
34|6 |62|ND4456 E2
17|5 |96|NJ5101
34|6 |62|ND4456
32|8 |89|NY2091
32|7 |91|FL6320
Section 9 # 30 11

13. CODE GENERATION implements GRACE JOIN
PROBE S1, E1: 1. Read S1 pg1 to IN. 2. Hash IN to HASH. 3. Read E1 to IN 4. Concatenate to OUT.
5. Read (next page of) E1 to IN. 6. Hash to HASH.
7. If match, Concatenate to OUT Flush HASH and IN when done Probing E1.
PROBE S2, E2: 1. Read S2 pg1 to IN 2. MOD3 hash IN to HASH (open addressing for collisions). S0
57|BROWN |NY2092 S1
25|CLAY |NJ5101 S2
17|BAID |NY2091
32|THAISZ|NJ5102
38|GOOD |FL6321 E0
CLAY|7 |68
OUT IN 1 2 3
Hash
CLAY|6 |76 E1
25|7 |68|ND4456
25|6 |76|NY2091
34|6 |62|ND4456 E2
17|5 |96|NJ5101
17|BAID |NY2091
32|8 |89|NY2091
32|7 |91|FL6320
32|THAISZ|NJ5102
Section 9 # 31 11

14. CODE GENERATION implements GRACE JOIN
PROBE S1, E1: 1. Read S1 pg1 to IN. 2. Hash IN to HASH. 3. Read E1 to IN 4. Concatenate to OUT.
5. Read (next page of) E1 to IN. 6. Hash to HASH.
7. If match, Concatenate to OUT Flush HASH and IN when done Probing E1.
PROBE S2, E2: 1. Read S2 pg1 to IN 2. MOD3 hash IN to HASH (open addressing for collisions).
3. Read S2 pg2 to IN 4. MOD3 hash IN to HASH (open addressing for collisions). S0
57|BROWN |NY2092 S1
25|CLAY |NJ5101 S2
17|BAID |NY2091
32|THAISZ|NJ5102
38|GOOD |FL6321 E0
CLAY|7 |68
OUT IN 1 2 3
Hash
CLAY|6 |76 E1
25|7 |68|ND4456
25|6 |76|NY2091
17|BAID |NY2091
34|6 |62|ND4456
32|THAISZ|NJ5102 E2
17|5 |96|NJ5101
38|GOOD |FL6321
32|8 |89|NY2091
32|7 |91|FL6320
Section 9 # 32 11

15. CODE GENERATION implements GRACE JOIN
PROBE S1, E1: 1. Read S1 pg1 to IN. 2. Hash IN to HASH. 3. Read E1 to IN 4. Concatenate to OUT.
5. Read (next page of) E1 to IN. 6. Hash to HASH.
7. If match, Concatenate to OUT Flush HASH and IN when done Probing E1.
PROBE S2, E2: 1. Read S2 pg1 to IN 2. MOD3 hash IN to HASH (open addressing for collisions).
3. Read S2 pg2 to IN 4. MOD3 hash IN to HASH (open addressing for collisions).
5.Read E2 to IN. 6.Hash to HASH. 7. If match, Concatenate to OUT... S0
57|BROWN |NY2092 S1
25|CLAY |NJ5101 S2
17|BAID |NY2091
32|THAISZ|NJ5102
38|GOOD |FL6321 E0
CLAY|7 |68
OUT IN 1 2 3
Hash
BAID |5|96
CLAY|6 |76
38|GOOD |FL6321 E1
25|7 |68|ND4456
25|6 |76|NY2091
17|BAID |NY2091
34|6 |62|ND4456
32|THAISZ|NJ5102 E2
17|5 |96|NJ5101
17|5 |96|NJ5101
32|8 |89|NY2091
32|8 |89|NY2091
32|7 |91|FL6320
Section 9 # 33 11

16. CODE GENERATION implements GRACE JOIN
PROBE S1, E1: 1. Read S1 pg1 to IN. 2. Hash IN to HASH. 3. Read E1 to IN 4. Concatenate to OUT.
5. Read (next page of) E1 to IN. 6. Hash to HASH.
7. If match, Concatenate to OUT Flush HASH and IN when done Probing E1.
PROBE S2, E2: 1. Read S2 pg1 to IN 2. MOD3 hash IN to HASH (open addressing for collisions).
3. Read S2 pg2 to IN 4. MOD3 hash IN to HASH (open addressing for collisions).
5.Read E2 to IN. 6.Hash to HASH. 7. If match, Concatenate to OUT... S0
57|BROWN |NY2092 S1
25|CLAY |NJ5101 S2
17|BAID |NY2091
32|THAISZ|NJ5102
38|GOOD |FL6321 E0
CLAY|7 |68
OUT IN 1 2 3
Hash
BAID |5|96
CLAY|6 |76
THAISZ|8|89
38|GOOD |FL6321 E1
25|7 |68|ND4456
25|6 |76|NY2091
17|BAID |NY2091
34|6 |62|ND4456
32|THAISZ|NJ5102 E2
17|5 |96|NJ5101
32|8 |89|NY2091
32|8 |89|NY2091
32|7 |91|FL6320
Section 9 # 34 11

17. CODE GENERATION implements GRACE JOIN
PROBE S1, E1: 1. Read S1 pg1 to IN. 2. Hash IN to HASH. 3. Read E1 to IN 4. Concatenate to OUT.
5. Read (next page of) E1 to IN. 6. Hash to HASH.
7. If match, Concatenate to OUT Flush HASH and IN when done Probing E1.
PROBE S2, E2: 1. Read S2 pg1 to IN 2. MOD3 hash IN to HASH (open addressing for collisions).
3. Read S2 pg2 to IN 4. MOD3 hash IN to HASH (open addressing for collisions).
5.Read E2 to IN. 6.Hash to HASH.
7. If match, Concatenate to OUT...(repeat until E2 empty)
8. Flush HASH and IN when done Probing E1. S0
57|BROWN |NY2092 S1
25|CLAY |NJ5101 S2
17|BAID |NY2091
32|THAISZ|NJ5102
38|GOOD |FL6321 E0
CLAY |7|68
OUT IN 1 2 3
Hash
THAISZ|7|91
BAID |5|96
CLAY |6|76
THAISZ|8|89
38|GOOD |FL6321 E1
25|7 |68|ND4456
25|6 |76|NY2091
17|BAID |NY2091
34|6 |62|ND4456
32|THAISZ|NJ5102 E2
17|5 |96|NJ5101
32|7 |91|FL6320
32|8 |89|NY2091
32|7 |91|FL6320
Section 9 # 35 11

18. CODE GENERATION implements the operator, HYBRID HASH JOIN
J4. HASH-JOIN: (a better way than GRACE JOIN):
HYBRID HASH JOIN of SS#E (developed by former chair of NDSU CS Dept., Dr. L. Shapiro):
Partition the M pages of main memory allocated to the join process as follows: One page for the IN, 0ne page for the OUT, B pages for hash buckets, R1..RB, Leave the rest for a large internal hash table, R0.
PARTIAL SORT S: Read each S page to IN, hash each record using h(S#)=MODB(S#) to R0..RB. If a record hashes to R0, apply an internal hash function, k(S#) which hashes the record to a slot in R0. Use open addressing for k-collisions. When an h-collision occurs in any page Ri i=1..B, flush that page to a disk file, called Si i=1..B.
PARTIALLY SORT E: Read each E page into IN, hash each record with h(S#) to R0..RB If record hashes to R0, apply internal hash function k(S#), and concatenate records that match to OUT. If a collision occurs in any page, Ri i=1..B, flush to temporary disk file, Ei i=1..B.
PROBE PHASE for pairs, Si and Ei i=1..B, do the same as in Grace Join.
Hybrid Hash Join can be done with Bit Filtering to eliminate non-participating tuples early and avoid wasted processing of non-participating tuples Much more detail and example walkthroughs can be found in the HTML version of these notes (also available from "Other Materials"
Section 9 # 36 11

19. CODE GENERATION implements the operator, HYBRID HASH JOIN
h=MOD k=MOD SELECT SNAME,C#,GRADE FROM S,E WHERE S.S#=E.S#;
Read each S-page to IN, hash each record using h(S#)=MOD3(S#) to R0,R1,R2. If h(S#)=0, k(S#) determines R0 slot (open addressing for collisions in R0). h collisions in R1, R2 flush to file, S1, S2 resp.
Similarly (note all h hashes goes to R1 or R2, So all E records flush to E1 and E2 and R0 is flushed too. S E
RID|S#|SNAME | LCODE
RID|S#|C#|GR| LCODE
1,0|17|BAID |NY2091
1,0|17|5 |96|NJ5101 S0
1,1|25|CLAY |NJ5101
1,1|25|7 |68|ND4456
2,0|32|THAISZ|NJ5102
2,0|25|6 |76|NY2091
2,1|57|BROWN |NY2092
2,1|32|8 |89|NY2091 S1
3,0|38|GOOD |FL6321
3,0|32|7 |91|FL6320
25|CLAY |NJ5101
3,1|34|6 |62|ND4456 S2 1 2 3
17|BAID |NY2091
OUT
32|THAISZ|NJ5102
38|GOOD |FL6321 R0
57|BROWN |NY2092 E0 R1 E1
25|7 |68|ND4456 R2
25|6 |76|NY2091
34|6 |62|ND4456 E2 IN
3,0|38|GOOD |FL6321
1,0|17|BAID |NY2091
2,0|32|THAISZ|NJ5102
17|5 |96|NJ5101
2,1|57|BROWN |NY2092
32|8 |89|NY2091
1,1|25|CLAY |NJ5101
32|7 |91|FL6320
Section 9 # 37 11

20. CODE GENERATION implements HYBRID JOIN
PROBE S1, E1: 1. Read S1 page-1 to IN. 2. Hash IN to HASH Read E1 to IN 4. Concatenate to OUT. S0 S1
25|CLAY |NJ5101 S2
17|BAID |NY2091
32|THAISZ|NJ5102
38|GOOD |FL6321 E0
CLAY|7 |68
OUT IN 1 2 3
Hash
CLAY|6 |76 E1
25|7 |68|ND4456
25|CLAY |NJ5101
25|6 |76|NY2091
34|6 |62|ND4456 E2
17|5 |96|NJ5101
25|7 |68|ND4456
32|8 |89|NY2091
25|6 |76|NY2091
32|7 |91|FL6320
Section 9 # 38 11

21. CODE GENERATION implements HYBRID JOIN
PROBE S1, E1: 1. Read S1 pg1 to IN. 2. Hash IN to HASH. 3. Read E1 to IN 4. Concatenate to OUT.
5. Read (next page of) E1 to IN. 6. Hash to HASH.
7. If match, Concatenate to OUT (Since OUT is full, flush OUT first.). But no match!
8. Flush HASH and IN when done with S1, E1 Probe (before starting Probe S2, E2). S0 S1
25|CLAY |NJ5101 S2
17|BAID |NY2091
32|THAISZ|NJ5102
38|GOOD |FL6321 E0
CLAY|7 |68
OUT IN 1 2 3
Hash
CLAY|6 |76 E1
25|7 |68|ND4456
25|CLAY |NJ5101
25|6 |76|NY2091
34|6 |62|ND4456 E2
17|5 |96|NJ5101
34|6 |62|ND4456
32|8 |89|NY2091
32|7 |91|FL6320
Section 9 # 39 11

22. CODE GENERATION implements HYBRID JOIN
PROBE S1, E1: 1. Read S1 pg1 to IN. 2. Hash IN to HASH. 3. Read E1 to IN 4. Concatenate to OUT.
5. Read (next page of) E1 to IN. 6. Hash to HASH.
7. If match, Concatenate to OUT Flush HASH and IN when done Probing E1.
PROBE S2, E2: 1. Read S2 pg1 to IN 2. MOD3 hash IN to HASH (open addressing for collisions). S0 S1
25|CLAY |NJ5101 S2
17|BAID |NY2091
32|THAISZ|NJ5102
38|GOOD |FL6321 E0
CLAY|7 |68
OUT IN 1 2 3
Hash
CLAY|6 |76 E1
25|7 |68|ND4456
25|6 |76|NY2091
34|6 |62|ND4456 E2
17|5 |96|NJ5101
17|BAID |NY2091
32|8 |89|NY2091
32|7 |91|FL6320
32|THAISZ|NJ5102
Section 9 # 40 11

23. CODE GENERATION implements HYBRID JOIN
PROBE S1, E1: 1. Read S1 pg1 to IN. 2. Hash IN to HASH. 3. Read E1 to IN 4. Concatenate to OUT.
5. Read (next page of) E1 to IN. 6. Hash to HASH.
7. If match, Concatenate to OUT Flush HASH and IN when done Probing E1.
PROBE S2, E2: 1. Read S2 pg1 to IN 2. MOD3 hash IN to HASH (open addressing for collisions).
3. Read S2 pg2 to IN 4. MOD3 hash IN to HASH (open addressing for collisions). S0 S1
25|CLAY |NJ5101 S2
17|BAID |NY2091
32|THAISZ|NJ5102
38|GOOD |FL6321 E0
CLAY|7 |68
OUT IN 1 2 3
Hash
CLAY|6 |76 E1
25|7 |68|ND4456
25|6 |76|NY2091
17|BAID |NY2091
34|6 |62|ND4456
32|THAISZ|NJ5102 E2
17|5 |96|NJ5101
38|GOOD |FL6321
32|8 |89|NY2091
32|7 |91|FL6320
Section 9 # 41 11

24. CODE GENERATION implements HYBRID JOIN
PROBE S1, E1: 1. Read S1 pg1 to IN. 2. Hash IN to HASH. 3. Read E1 to IN 4. Concatenate to OUT.
5. Read (next page of) E1 to IN. 6. Hash to HASH.
7. If match, Concatenate to OUT Flush HASH and IN when done Probing E1.
PROBE S2, E2: 1. Read S2 pg1 to IN 2. MOD3 hash IN to HASH (open addressing for collisions).
3. Read S2 pg2 to IN 4. MOD3 hash IN to HASH (open addressing for collisions).
5.Read E2 to IN. 6.Hash to HASH. 7. If match, Concatenate to OUT... S0 S1
25|CLAY |NJ5101 S2
17|BAID |NY2091
32|THAISZ|NJ5102
38|GOOD |FL6321 E0
CLAY|7 |68
OUT IN 1 2 3
Hash
BAID |5|96
CLAY|6 |76
38|GOOD |FL6321 E1
25|7 |68|ND4456
25|6 |76|NY2091
17|BAID |NY2091
34|6 |62|ND4456
32|THAISZ|NJ5102 E2
17|5 |96|NJ5101
17|5 |96|NJ5101
32|8 |89|NY2091
32|8 |89|NY2091
32|7 |91|FL6320
Section 9 # 42 11

25. CODE GENERATION implements HYBRID JOIN
PROBE S1, E1: 1. Read S1 pg1 to IN. 2. Hash IN to HASH. 3. Read E1 to IN 4. Concatenate to OUT.
5. Read (next page of) E1 to IN. 6. Hash to HASH.
7. If match, Concatenate to OUT Flush HASH and IN when done Probing E1.
PROBE S2, E2: 1. Read S2 pg1 to IN 2. MOD3 hash IN to HASH (open addressing for collisions).
3. Read S2 pg2 to IN 4. MOD3 hash IN to HASH (open addressing for collisions).
5.Read E2 to IN. 6.Hash to HASH. 7. If match, Concatenate to OUT... S0 S1
25|CLAY |NJ5101 S2
17|BAID |NY2091
32|THAISZ|NJ5102
38|GOOD |FL6321 E0
CLAY|7 |68
OUT IN 1 2 3
Hash
BAID |5|96
CLAY|6 |76
THAISZ|8|89
38|GOOD |FL6321 E1
25|7 |68|ND4456
25|6 |76|NY2091
17|BAID |NY2091
34|6 |62|ND4456
32|THAISZ|NJ5102 E2
17|5 |96|NJ5101
32|8 |89|NY2091
32|8 |89|NY2091
32|7 |91|FL6320
Section 9 # 43 11

26. CODE GENERATION implements HYBRID JOIN
PROBE S1, E1: 1. Read S1 pg1 to IN. 2. Hash IN to HASH. 3. Read E1 to IN 4. Concatenate to OUT.
5. Read (next page of) E1 to IN. 6. Hash to HASH.
7. If match, Concatenate to OUT Flush HASH and IN when done Probing E1.
PROBE S2, E2: 1. Read S2 pg1 to IN 2. MOD3 hash IN to HASH (open addressing for collisions).
3. Read S2 pg2 to IN 4. MOD3 hash IN to HASH (open addressing for collisions).
5.Read E2 to IN. 6.Hash to HASH.
7. If match, Concatenate to OUT...(repeat until E2 empty)
8. Flush HASH and IN when done Probing E1. S0 S1
25|CLAY |NJ5101 S2
17|BAID |NY2091
32|THAISZ|NJ5102
38|GOOD |FL6321 E0
CLAY |7|68
OUT IN 1 2 3
Hash
THAISZ|7|91
BAID |5|96
CLAY |6|76
THAISZ|8|89
38|GOOD |FL6321 E1
25|7 |68|ND4456
25|6 |76|NY2091
17|BAID |NY2091
34|6 |62|ND4456
32|THAISZ|NJ5102 E2
17|5 |96|NJ5101
32|7 |91|FL6320
32|8 |89|NY2091
32|7 |91|FL6320
Section 9 # 44 11

27. CODE generation of HYBRID HASH JOIN using R2 as internal hash bucket!
h=MOD3 k=MOD4 SELECT SNAME,C#,GRADE FROM S,E WHERE S.S#=E.S#;
BUILD S: Read each S-page to IN, hash each record using h(S#)=MOD3(S#) to R0,R1,R2. If h(S#)=2, k(S#) determines R2 slot (open addressing for R2). h collisions in R1, R0 flush to file, S1, S0 resp. S E
RID|S#|SNAME | LCODE
RID|S#|C#|GR| LCODE
1,0|17|BAID |NY2091
1,0|17|5 |96|NJ5101
1,1|25|CLAY |NJ5101
1,1|25|7 |68|ND4456
2,0|32|THAISZ|NJ5102
2,0|25|6 |76|NY2091 S0
2,1|57|BROWN |NY2092
2,1|32|8 |89|NY2091
57|BROWN |NY2092
3,0|38|GOOD |FL6321
3,0|32|7 |91|FL6320
3,1|34|6 |62|ND4456 S1
25|CLAY |NJ5101
OUT R0 R1 E0 R2 1 2 3 E1 IN
2,0|32|THAISZ|NJ5102
3,0|38|GOOD |FL6321
1,0|17|BAID |NY2091
1,1|25|CLAY |NJ5101
2,1|57|BROWN |NY2092
Section 9 # 45 11

28. CODE generation implements HYBRID HASH JOIN using R2 as internal hash bucket!
h=MOD3 k=MOD4 SELECT SNAME,C#,GRADE FROM S,E WHERE S.S#=E.S#;
BUILD E: Read first E-page to IN, hash each record using h(S#)=MOD3(S#) to R0,R1,R2. If h(S#)=2, k(S#) determines R2 slot (open addressing for R2). If match, concatenate to OUT. h collisions in R1, R0 flush to file, E1, E0 respectively. S E
RID|S#|SNAME | LCODE
RID|S#|C#|GR| LCODE
1,0|17|BAID |NY2091
1,0|17|5 |96|NJ5101
1,1|25|CLAY |NJ5101
1,1|25|7 |68|ND4456
2,0|32|THAISZ|NJ5102
2,0|25|6 |76|NY2091 S0
2,1|57|BROWN |NY2092
2,1|32|8 |89|NY2091
57|BROWN |NY2092
3,0|38|GOOD |FL6321
3,0|32|7 |91|FL6320
3,1|34|6 |62|ND4456 S1 S1
25|CLAY |NJ5101 S2
BAID |5 |96
OUT R0 R1 E0 R2 1 2 3
32|THAISZ|NJ5102
17|BAID |NY2091 E1
38|GOOD |FL6321
1,0|17|5 |96|NJ5101 IN
1,1|25|7 |68|ND4456
Section 9 # 46 11

29. CODE GEN implements HYBRID HASH JOIN using R2 as internal hash bucket!
h=MOD3 k=MOD4 SELECT SNAME,C#,GRADE FROM S,E WHERE S.S#=E.S#;
BUILD E: Read second E-page to IN, hash each record using h(S#)=MOD3(S#) to R0,R1,R2. If h(S#)=2, k(S#) determines R2 slot (open addressing for R2). If match, concatenate to OUT. h collisions in R1, R0 flush to file, E1, E0 respectively. S E
RID|S#|SNAME | LCODE
RID|S#|C#|GR| LCODE
1,0|17|BAID |NY2091
1,0|17|5 |96|NJ5101
1,1|25|CLAY |NJ5101
1,1|25|7 |68|ND4456
2,0|32|THAISZ|NJ5102
2,0|25|6 |76|NY2091 S0
2,1|57|BROWN |NY2092
2,1|32|8 |89|NY2091
57|BROWN |NY2092
3,0|38|GOOD |FL6321
3,0|32|7 |91|FL6320
3,1|34|6 |62|ND4456 S1 S1
25|CLAY |NJ5101 S2
BAID |5 |96
OUT
THAISZ|8 |89 R0 R1
25|7 |68|ND4456 E0 R2 1 2 3
32|THAISZ|NJ5102
17|BAID |NY2091 E1
38|GOOD |FL6321
2,0|25|6 |76|NY2091 IN
2,1|32|8 |89|NY2091
Section 9 # 47 11

30. CODE GEN implements HYBRID HASH JOIN using R2 as internal hash bucket!
h=MOD3 k=MOD4 SELECT SNAME,C#,GRADE FROM S,E WHERE S.S#=E.S#;
BUILD E: Read third E-page to IN, hash each record using h(S#)=MOD3(S#) to R0,R1,R2. If h(S#)=2, k(S#) determines R2 slot (open addressing for R2). If match, concatenate to OUT. h collisions in R1, R0 flush to file, E1, E0 respectively. When done building E, flush R2. S E
RID|S#|SNAME | LCODE
RID|S#|C#|GR| LCODE
1,0|17|BAID |NY2091
1,0|17|5 |96|NJ5101
1,1|25|CLAY |NJ5101
1,1|25|7 |68|ND4456
2,0|32|THAISZ|NJ5102
2,0|25|6 |76|NY2091 S0
2,1|57|BROWN |NY2092
2,1|32|8 |89|NY2091
57|BROWN |NY2092
3,0|38|GOOD |FL6321
3,0|32|7 |91|FL6320
3,1|34|6 |62|ND4456 S1 S1
25|CLAY |NJ5101 S2
BAID |5 |96
THAISZ|7 |91
OUT
THAISZ|8 |89 R0 R1
25|7 |68|ND4456 E0
25|6 |76|NY2091 R2 1 2 3
32|THAISZ|NJ5102
17|BAID |NY2091 E1
25|7 |68|ND4456
38|GOOD |FL6321
25|6 |76|NY2091
34|6 |62|ND4456 IN
3,0|32|7 |91|FL6320
3,1|34|6 |62|ND4456
Section 9 # 48 11

31. CODE GEN implements HYBRID HASH JOIN using R2 as internal hash bucket probe:
Note: If memory allocation is static, use all Ri pages for internal hash function! So k=MOD8
h=MOD3 k=MOD4 SELECT SNAME,C#,GRADE FROM S,E WHERE S.S#=E.S#;
PROBE S:
Notice how much more efficient the probe phase of HH JOIN is than Grace JOIN when the internal Hash table is chosen to apply to the right bucket!
(And how it may not be faster, if that decision is badly made!) S0
57|BROWN |NY2092 S1 S1
25|CLAY |NJ5101
25|CLAY |NJ5101 S2
BAID |5 |96 IN R2 1 2 3
OUT 4 5 6 7
THAISZ|7 |91
THAISZ|6 |76
THAISZ|8 |89
CLAY |7 |68 E0 E1
25|7 |68|ND4456
25|6 |76|NY2091
34|6 |62|ND4456
25|7 |68|ND4456
25|6 |76|NY2091
Section 9 # 49 11