1. CPSC-608 Database Systems
Fall 2018
Instructor: Jianer Chen
Office: HRBB 315C
Phone:
Notes #15

2. What Does DBMS Do? understand the program P
An input database program P
understand the program P
parse tree
translate the program P into an
expression E in relational algebra
logic query plan
convert E into an algorithm using
algorithms in the collection C
Machine executable code

3. subqueries in the FROM clause
subqueries in the FROM clause
\\ Parse tree to Exp tree: for SFW
1. create a π node;
2. collect the attributes in child-2
and attach them to the π node;
3. IF child-5 ≠ NULL THEN
create a σ node and make it
the child of the π node;
get the conditions in child-6
and attach it to the σ node;
4. create a × node and make it the
child of the σ node;
5. make the tables in child-4 the
children of the × node;
6. IF child-7 ≠ NULL THEN …
SELECT c
FROM S(a,b), (SELECT * FROM T(b,c) WHERE c = 10) t
WHERE S.b = t.b AND a>4;
<statement>
<select-statement>
select
<select-list>
from
<tbl-list>
where
<search-condition>
<select-sublist>
<tbl-name> ,
<tbl-list>
<b-term>
<column-name>
S(a,b)
<tbl-name>
<b-facor>
<b-term>
and c
<b-primary>
<b-facor>
S(a,b) t c × π σ
S.b=t.b AND a>4
<comp-pred>
<b-primary>
<exp>
<co-op>
<exp>
<comp-pred>
<term>
<term> =
<exp>
<co-op>
<exp>
<column-name>
<column-name>
<term>
<term>
>
S.b
T.b
<column-name>
<integer> a 4
parse tree for
(SELECT *
FROM T(b,c)
WHERE c = 10) t
logic plan for
(SELECT *
FROM T(b,c)
WHERE c = 10) t

4. subqueries in the WHERE clause

5. subqueries in the WHERE clause
subqueries in the WHERE clause
SELECT b
FROM S(a,b)
WHERE S.a > ANY (SELECT c FROM T(c,d) WHERE d = 10) ;

6. subqueries in the WHERE clause
subqueries in the WHERE clause
SELECT b
FROM S(a,b)
WHERE S.a > ANY (SELECT c FROM T(c,d) WHERE d = 10) ;

7. subqueries in the WHERE clause
subqueries in the WHERE clause
SELECT b
FROM S(a,b)
WHERE S.a > ANY (SELECT c FROM T(c,d) WHERE d = 10) ;
\\ Parse tree to Exp tree: for SFW
1. create a π node;
2. collect the attributes in child-2
and attach them to the π node;
3. IF child-5 ≠ NULL THEN
create a σ node and make it
the child of the π node;
get the conditions in child-6
and attach it to the σ node;
4. create a × node and make it the
child of the σ node;
5. make the tables in child-4 the
children of the × node;
6. IF child-7 ≠ NULL THEN …
Can we make a logic query plan like this?
S(a,b) b π σ
S.a > ANY (SELECT c FROM T(c,d) WHERE d= 10)

8. subqueries in the WHERE clause
subqueries in the WHERE clause
SELECT b
FROM S(a,b)
WHERE S.a > ANY (SELECT c FROM T(c,d) WHERE d = 10) ;
\\ Parse tree to Exp tree: for SFW
1. create a π node;
2. collect the attributes in child-2
and attach them to the π node;
3. IF child-5 ≠ NULL THEN
create a σ node and make it
the child of the π node;
get the conditions in child-6
and attach it to the σ node;
4. create a × node and make it the
child of the σ node;
5. make the tables in child-4 the
children of the × node;
6. IF child-7 ≠ NULL THEN …
Can we make a logic query plan like this?
S(a,b) b π σ
S.a > ANY (SELECT c FROM T(c,d) WHERE d= 10)
NO! Conditions in σ involved in subqueries can cause
significant inefficiency and/or even logic inconsistency

9. Then what will we do? subqueries in the WHERE clause
subqueries in the WHERE clause
SELECT b
FROM S(a,b)
WHERE S.a > ANY (SELECT c FROM T(c,d) WHERE d = 10) ;
\\ Parse tree to Exp tree: for SFW
1. create a π node;
2. collect the attributes in child-2
and attach them to the π node;
3. IF child-5 ≠ NULL THEN
create a σ node and make it
the child of the π node;
get the conditions in child-6
and attach it to the σ node;
4. create a × node and make it the
child of the σ node;
5. make the tables in child-4 the
children of the × node;
6. IF child-7 ≠ NULL THEN …
Can we make a logic query plan like this?
S(a,b) b π σ
S.a > ANY (SELECT c FROM T(c,d) WHERE d= 10)
Then what will we do?

10. subqueries in the WHERE clause
subqueries in the WHERE clause
EXIST R
s IN R
s > ALL R
s > ANY R
SELECT b
FROM S(a,b)
WHERE S.a > ANY (SELECT c FROM T(c,d) WHERE d = 10) ;

11. subqueries in the WHERE clause
subqueries in the WHERE clause
EXIST R
s IN R
s > ALL R
s > ANY R
SELECT b
FROM S(a,b)
WHERE S.a > ANY (SELECT c FROM T(c,d) WHERE d = 10) ;
Each operation has a different conversion procedure.
In general,
Convert the subquery into a logic plan;
Collect the attributes for the condition;
Make a cross product with the “main” relations;
Apply the conditions in the cross product.

12. subqueries in the WHERE clause
subqueries in the WHERE clause
1. Convert the subquery into a logic plan;
2. Collect the attributes for the condition;
3. Make a cross product with the “main” relations;
4. Apply the conditions in the cross product.
SELECT b
FROM S(a,b)
WHERE S.a > ANY (SELECT c FROM T(c,d) WHERE d = 10) ;

13. subqueries in the WHERE clause
subqueries in the WHERE clause
1. Convert the subquery into a logic plan;
2. Collect the attributes for the condition;
3. Make a cross product with the “main” relations;
4. Apply the conditions in the cross product.
SELECT b
FROM S(a,b)
WHERE S.a > ANY (SELECT c FROM T(c,d) WHERE d = 10) ;
<statement>
<select-statement>
select
<select-list>
from
<tbl-list>
where
<search-condition>
<select-sublist>
<tbl-name>
<b-term>
<column-name>
<b-facor>
S(a,b) b
<b-primary>
<comp-pred>
<exp>
<co-op>
<exp>
<term>
>
any
<column-name>
S.a
Parse tree for
SELECT c
FROM T(c,d)
WHERE d = 10

14. subqueries in the WHERE clause
subqueries in the WHERE clause
1. Convert the subquery into a logic plan;
2. Collect the attributes for the condition;
3. Make a cross product with the “main” relations;
4. Apply the conditions in the cross product.
SELECT b
FROM S(a,b)
WHERE S.a > ANY (SELECT c FROM T(c,d) WHERE d = 10) ;
<statement>
<select-statement>
select
<select-list>
from
<tbl-list>
where
<search-condition>
<select-sublist>
<tbl-name>
<b-term>
<column-name>
<b-facor>
S(a,b) b
<b-primary>
<comp-pred>
<exp>
<co-op>
<exp>
<term>
>
any
<column-name>
S.a
Parse tree for
SELECT c
FROM T(c,d)
WHERE d = 10
logic plan for
SELECT c
FROM T(c,d)
WHERE d = 10

15. subqueries in the WHERE clause
subqueries in the WHERE clause
1. Convert the subquery into a logic plan;
2. Collect the attributes for the condition;
3. Make a cross product with the “main” relations;
4. Apply the conditions in the cross product.
SELECT b
FROM S(a,b)
WHERE S.a > ANY (SELECT c FROM T(c,d) WHERE d = 10) ;
<statement>
<select-statement>
select
<select-list>
from
<tbl-list>
where
<search-condition>
<select-sublist>
<tbl-name>
<b-term>
<column-name>
<b-facor>
S(a,b) b
<b-primary>
<comp-pred> σ
d = 10 c π
T(c,d)
<exp>
<co-op>
<exp>
<term>
>
any
<column-name>
S.a
Parse tree for
SELECT c
FROM T(c,d)
WHERE d = 10
logic plan for
SELECT c
FROM T(c,d)
WHERE d = 10

16. subqueries in the WHERE clause
subqueries in the WHERE clause
1. Convert the subquery into a logic plan;
2. Collect the attributes for the condition;
3. Make a cross product with the “main” relations;
4. Apply the conditions in the cross product.
SELECT b
FROM S(a,b)
WHERE S.a > ANY (SELECT c FROM T(c,d) WHERE d = 10) ;
<statement>
<select-statement>
select
<select-list>
from
<tbl-list>
where
<search-condition>
<select-sublist>
<tbl-name>
<b-term>
<column-name>
<b-facor>
S(a,b) b
<b-primary> ×
<comp-pred> σ
d = 10 c π
T(c,d)
S(a,b)
<exp>
<co-op>
<exp>
<term>
>
any
<column-name>
S.a
Parse tree for
SELECT c
FROM T(c,d)
WHERE d = 10
logic plan for
SELECT c
FROM T(c,d)
WHERE d = 10

17. subqueries in the WHERE clause
subqueries in the WHERE clause
1. Convert the subquery into a logic plan;
2. Collect the attributes for the condition;
3. Make a cross product with the “main” relations;
4. Apply the conditions in the cross product.
SELECT b
FROM S(a,b)
WHERE S.a > ANY (SELECT c FROM T(c,d) WHERE d = 10) ;
<statement>
<select-statement> b π
select
<select-list>
from
<tbl-list>
where
<search-condition>
<select-sublist>
<tbl-name>
<b-term> σ
S.a > U.c
<column-name>
<b-facor>
S(a,b) b
<b-primary> ×
<comp-pred> σ
d = 10 c π
T(c,d)
S(a,b)
<exp>
<co-op>
<exp>
<term>
>
any
<column-name>
S.a
Parse tree for
SELECT c
FROM T(c,d)
WHERE d = 10
logic plan for
SELECT c
FROM T(c,d)
WHERE d = 10

18. subqueries in the WHERE clause
subqueries in the WHERE clause
1. Convert the subquery into a logic plan;
2. Collect the attributes for the condition;
3. Make a cross product with the “main” relations;
4. Apply the conditions in the cross product.
SELECT b
FROM S(a,b)
WHERE S.a > ANY (SELECT c FROM T(c,d) WHERE d = 10) ;
<statement>
<select-statement> b π
select
<select-list>
from
<tbl-list>
where
<search-condition>
<select-sublist>
<tbl-name>
<b-term> σ
S.a > U.c
<column-name>
<b-facor>
S(a,b) b
<b-primary> ×
<comp-pred> σ
d = 10 c π
T(c,d)
S(a,b)
<exp>
<co-op>
<exp>
<term>
>
any
<column-name>
S.a
Parse tree for
SELECT c
FROM T(c,d)
WHERE d = 10

19. subqueries in the WHERE clause
subqueries in the WHERE clause
1. Convert the subquery into a logic plan;
2. Collect the attributes for the condition;
3. Make a cross product with the “main” relations;
4. Apply the conditions in the cross product.
SELECT b
FROM S(a,b)
WHERE S.a > ANY (SELECT c FROM T(c,d) WHERE d = 10) ;
<statement>
<select-statement> b π
select
<select-list>
from
<tbl-list>
where
<search-condition>
<select-sublist>
<tbl-name>
<b-term> σ
S.a > U.c
<column-name>
<b-facor>
S(a,b) b
<b-primary> ×
<comp-pred>
S(a,b) δ
<exp>
<co-op>
<exp> σ
d = 10 c π
T(c,d)
<term>
>
any
<column-name>
S.a
Parse tree for
SELECT c
FROM T(c,d)
WHERE d = 10

20. What Does DBMS Do? √ understand the program P
An input database program P
understand the program P
parse tree
translate the program P into an
expression E in relational algebra √
logic query plan
convert E into an algorithm using
algorithms in the collection C
Machine executable code

21. What Does DBMS Do? √ understand the program P
An input database program P
understand the program P
View processing,
Semantic checking
parse tree
preprocessing
parse tree
translate the program P into an
expression E in relational algebra √
logic query plan
convert E into an algorithm using
algorithms in the collection C
Machine executable code

22. View Processing

23. View Processing CREATE VIEW V AS SELECT a, b FROM T(a,g), U(h,b)
WHERE T.g > U.h

24. View Processing CREATE VIEW V AS SELECT a, b FROM T(a,g), U(h,b)
<statement>
<select-statement>
select
<select-list>
from
<tbl-list>
where
<search-condition>
<tbl-name>
T(a,g)
<b-term>
<b-facor>
<b-primary>
<comp-pred>
<exp>
<co-op>
<term>
T.g
<column-name>
<select-sublist> b
> , a
U.h
CREATE VIEW V AS
SELECT a, b
FROM T(a,g), U(h,b)
WHERE T.g > U.h

25. View Processing SELECT a, d FROM V(a,b), S(c,d) WHERE V.b = S.c
U(h,b)
<statement>
<select-statement>
select
<select-list>
from
<tbl-list>
where
<search-condition>
<tbl-name>
T(a,g)
<b-term>
<b-facor>
<b-primary>
<comp-pred>
<exp>
<co-op>
<term>
T.g
<column-name>
<select-sublist> b
> , a
U.h
SELECT a, d
FROM V(a,b), S(c,d)
WHERE V.b = S.c
CREATE VIEW V AS
SELECT a, b
FROM T(a,g), U(h,b)
WHERE T.g > U.h

26. View Processing V is a view SELECT a, d FROM V(a,b), S(c,d)
U(h,b)
<statement>
<select-statement>
select
<select-list>
from
<tbl-list>
where
<search-condition>
<tbl-name>
T(a,g)
<b-term>
<b-facor>
<b-primary>
<comp-pred>
<exp>
<co-op>
<term>
T.g
<column-name>
<select-sublist> b
> , a
U.h
V is a view
SELECT a, d
FROM V(a,b), S(c,d)
WHERE V.b = S.c
CREATE VIEW V AS
SELECT a, b
FROM T(a,g), U(h,b)
WHERE T.g > U.h

27. View Processing V is a view SELECT a, d FROM V(a,b), S(c,d)
U(h,b)
<statement>
<select-statement>
select
<select-list>
from
<tbl-list>
where
<search-condition>
<tbl-name>
T(a,g)
<b-term>
<b-facor>
<b-primary>
<comp-pred>
<exp>
<co-op>
<term>
T.g
<column-name>
<select-sublist> b
> , a
U.h
V is a view
SELECT a, d
FROM V(a,b), S(c,d)
WHERE V.b = S.c
<statement>
<select-statement>
select
<select-list>
from
<tbl-list>
where ,
<column-name> ,
<search-condition>
<tbl-name>
<tbl-list>
<select-sublist> a
<b-term>
V(a,b)
<tbl-name>
<column-name>
<b-facor> d
S(c,d)
<b-primary>
<comp-pred>
CREATE VIEW V AS
SELECT a, b
FROM T(a,g), U(h,b)
WHERE T.g > U.h
<exp>
<co-op>
<exp>
<term> =
<term>
<column-name>
V.b
S.c

28. View Processing V is a view SELECT a, d FROM V(a,b), S(c,d)
U(h,b)
<statement>
<select-statement>
select
<select-list>
from
<tbl-list>
where
<search-condition>
<tbl-name>
T(a,g)
<b-term>
<b-facor>
<b-primary>
<comp-pred>
<exp>
<co-op>
<term>
T.g
<column-name>
<select-sublist> b
> , a
U.h
V is a view
SELECT a, d
FROM V(a,b), S(c,d)
WHERE V.b = S.c
<statement>
<select-statement>
select
<select-list>
from
<tbl-list>
where ,
<column-name> ,
<search-condition>
<tbl-name>
<tbl-list>
<select-sublist> a
<b-term>
V(a,b)
<tbl-name>
<column-name>
<b-facor> d
S(c,d)
<b-primary>
<comp-pred>
CREATE VIEW V AS
SELECT a, b
FROM T(a,g), U(h,b)
WHERE T.g > U.h
<exp>
<co-op>
<exp>
<term> =
<term>
<column-name>
V.b
S.c

29. View Processing V is a view replace it by its parse tree SELECT a, d
U(h,b)
<statement>
<select-statement>
select
<select-list>
from
<tbl-list>
where
<search-condition>
<tbl-name>
T(a,g)
<b-term>
<b-facor>
<b-primary>
<comp-pred>
<exp>
<co-op>
<term>
T.g
<column-name>
<select-sublist> b
> , a
U.h
V is a view
SELECT a, d
FROM V(a,b), S(c,d)
WHERE V.b = S.c
<statement>
<select-statement>
select
<select-list>
from
<tbl-list>
where ,
<column-name> ,
<search-condition>
<tbl-name>
<tbl-list>
<select-sublist> a
<b-term>
V(a,b)
<tbl-name>
<column-name>
<b-facor> d
S(c,d)
<b-primary>
<comp-pred>
CREATE VIEW V AS
SELECT a, b
FROM T(a,g), U(h,b)
WHERE T.g > U.h
<exp>
<co-op>
<exp>
replace it by
its parse tree
<term> =
<term>
<column-name>
V.b
S.c

30. View Processing V is a view SELECT a, d FROM V(a,b), S(c,d)
U(h,b)
<statement>
<select-statement>
select
<select-list>
from
<tbl-list>
where
<search-condition>
<tbl-name>
T(a,g)
<b-term>
<b-facor>
<b-primary>
<comp-pred>
<exp>
<co-op>
<term>
T.g
<column-name>
<select-sublist> b
> , a
U.h
V is a view
SELECT a, d
FROM V(a,b), S(c,d)
WHERE V.b = S.c
<statement>
<select-statement>
select
<select-list>
from
<tbl-list>
where ,
<column-name> ,
<tbl-list>
<search-condition>
<tbl-name>
<select-sublist> a
<b-term>
V(a,b)
<tbl-name>
<column-name>
<b-facor>
U(h,b)
<statement>
<select-statement>
select
<select-list>
from
<tbl-list>
where
<search-condition>
<tbl-name>
T(a,g)
<b-term>
<b-facor>
<b-primary>
<comp-pred>
<exp>
<co-op>
<term>
T.g
<column-name>
<select-sublist> b
> , a
U.h d
S(c,d)
<b-primary>
<comp-pred>
CREATE VIEW V AS
SELECT a, b
FROM T(a,g), U(h,b)
WHERE T.g > U.h
<exp>
<co-op>
<exp>
<column-name>
<term> =
<term>
<column-name>
V.b
S.c

31. View Processing V is a view Therefore, for each CREATE VIEW
U(h,b)
<statement>
<select-statement>
select
<select-list>
from
<tbl-list>
where
<search-condition>
<tbl-name>
T(a,g)
<b-term>
<b-facor>
<b-primary>
<comp-pred>
<exp>
<co-op>
<term>
T.g
<column-name>
<select-sublist> b
> , a
U.h
V is a view
SELECT a, d
FROM V(a,b), S(c,d)
WHERE V.b = S.c
<statement>
<select-statement>
select
<select-list>
from
<tbl-list>
where ,
<column-name> ,
<search-condition>
<tbl-name>
<tbl-list>
<select-sublist> a
<b-term>
V(a,b)
<tbl-name>
<column-name>
<b-facor>
U(h,b)
<statement>
<select-statement>
select
<select-list>
from
<tbl-list>
where
<search-condition>
<tbl-name>
T(a,g)
<b-term>
<b-facor>
<b-primary>
<comp-pred>
<exp>
<co-op>
<term>
T.g
<column-name>
<select-sublist> b
> , a
U.h d
S(c,d)
<b-primary>
<comp-pred>
CREATE VIEW V AS
SELECT a, b
FROM T(a,g), U(h,b)
WHERE T.g > U.h
<exp>
<co-op>
<exp>
<column-name>
<term> =
<term>
<column-name>
V.b
S.c
Therefore, for each CREATE VIEW
statement, construct its parse tree.
In the parse tree for a statement that
uses the view, replace the view name
with the parse tree for the view.

32. What Does DBMS Do? √ √ understand the program P
An input database program P
understand the program P
View processing,
Semantic checking
parse tree √
preprocessing
parse tree
translate the program P into an
expression E in relational algebra √
logic query plan
convert E into an algorithm using
algorithms in the collection C
Machine executable code

33. What Does DBMS Do? √ √ √ understand the program P
An input database program P √
understand the program P
View processing,
Semantic checking
parse tree √
preprocessing
parse tree
translate the program P into an
expression E in relational algebra √
logic query plan
convert E into an algorithm using
algorithms in the collection C
Machine executable code

34. parse tree-lqp convertor
What Does DBMS Do?
An input database program P
View processing,
Semantic checking
parser
parse tree
preprocessing
parse tree
parse tree-lqp convertor
logic query plan
Lqp-pqp convertor
physical query plan
Machine executable code

35. parse tree-lqp convertor
What Does DBMS Do?
An input database program P
SELECT c
FROM S(a,b), T(b,c)
WHERE S.b = T.b AND a>4;
View processing,
Semantic checking
parser
parse tree
preprocessing
parse tree
parse tree-lqp convertor
logic query plan
Lqp-pqp convertor
physical query plan
Machine executable code

36. parse tree-lqp convertor
What Does DBMS Do?
An input database program P
SELECT c
FROM S(a,b), T(b,c)
WHERE S.b = T.b AND a>4;
View processing,
Semantic checking
parser
<statement>
<select-statement>
select
<select-list>
from
<tbl-list>
where
<search-condition>
<select-sublist>
<column-name>
<tbl-name> ,
S(a,b)
<b-term>
<b-facor>
and
T(b,c)
<b-primary>
<comp-pred>
<exp>
<co-op> =
<term>
<factor>
S.b
T.b
> a 4
<integer>
parse tree
preprocessing
parse tree
parse tree-lqp convertor
logic query plan
Lqp-pqp convertor
physical query plan
Machine executable code

37. parse tree-lqp convertor
What Does DBMS Do?
An input database program P
SELECT c
FROM S(a,b), T(b,c)
WHERE S.b = T.b AND a>4;
View processing,
Semantic checking
parser
<statement>
<select-statement>
select
<select-list>
from
<tbl-list>
where
<search-condition>
<select-sublist>
<column-name>
<tbl-name> ,
S(a,b)
<b-term>
<b-facor>
and
T(b,c)
<b-primary>
<comp-pred>
<exp>
<co-op> =
<term>
<factor>
S.b
T.b
> a 4
<integer>
parse tree
preprocessing
parse tree
parse tree-lqp convertor
S(a,b)
T(b,c) c × π σ
S.b=T.b AND a>4
logic query plan
Lqp-pqp convertor
physical query plan
Machine executable code

38. parse tree-lqp convertor
What Does DBMS Do?
An input database program P
SELECT c
FROM S(a,b), T(b,c)
WHERE S.b = T.b AND a>4;
Prepare a collection A of efficient algorithms for operations in relational algebra;
View processing,
Semantic checking
parser
<statement>
<select-statement>
select
<select-list>
from
<tbl-list>
where
<search-condition>
<select-sublist>
<column-name>
<tbl-name> ,
S(a,b)
<b-term>
<b-facor>
and
T(b,c)
<b-primary>
<comp-pred>
<exp>
<co-op> =
<term>
<factor>
S.b
T.b
> a 4
<integer>
parse tree
preprocessing
parse tree
parse tree-lqp convertor
S(a,b)
T(b,c) c × π σ
S.b=T.b AND a>4
logic query plan
Lqp-pqp convertor
physical query plan
Machine executable code

39. parse tree-lqp convertor
What Does DBMS Do?
An input database program P
SELECT c
FROM S(a,b), T(b,c)
WHERE S.b = T.b AND a>4;
Prepare a collection A of efficient algorithms for operations in relational algebra;
View processing,
Semantic checking
parser
<statement>
<select-statement>
select
<select-list>
from
<tbl-list>
where
<search-condition>
<select-sublist>
<column-name>
<tbl-name> ,
S(a,b)
<b-term>
<b-facor>
and
T(b,c)
<b-primary>
<comp-pred>
<exp>
<co-op> =
<term>
<factor>
S.b
T.b
> a 4
<integer>
parse tree
preprocessing
parse tree
parse tree-lqp convertor
S(a,b)
T(b,c) c × π σ
S.b=T.b AND a>4
logic query plan
output
Lqp-pqp convertor
Projection(c)
physical query plan
Select(S.b=T.b & a>4)
Alg-CrossProd
Machine executable code
ScanTable(S(a,b))
ScanTable(T(b,c))

40. parse tree-lqp convertor
What Does DBMS Do?
An input database program P
SELECT c
FROM S(a,b), T(b,c)
WHERE S.b = T.b AND a>4;
Prepare a collection A of efficient algorithms for operations in relational algebra;
View processing,
Semantic checking
parser
<statement>
<select-statement>
select
<select-list>
from
<tbl-list>
where
<search-condition>
<select-sublist>
<column-name>
<tbl-name> ,
S(a,b)
<b-term>
<b-facor>
and
T(b,c)
<b-primary>
<comp-pred>
<exp>
<co-op> =
<term>
<factor>
S.b
T.b
> a 4
<integer>
parse tree
preprocessing
parse tree
parse tree-lqp convertor
S(a,b)
T(b,c) c × π σ
S.b=T.b AND a>4
logic query plan
output
Lqp-pqp convertor
Projection(c)
physical query plan
In general
a pretty bad
algorithm
Select(S.b=T.b & a>4)
Alg-CrossProd
Machine executable code
ScanTable(S(a,b))
ScanTable(T(b,c))

41. parse tree-lqp convertor
What Does DBMS Do?
An input database program P
SELECT c
FROM S(a,b), T(b,c)
WHERE S.b = T.b AND a>4;
Prepare a collection A of efficient algorithms for operations in relational algebra;
View processing,
Semantic checking
parser
<statement>
<select-statement>
select
<select-list>
from
<tbl-list>
where
<search-condition>
<select-sublist>
<column-name>
<tbl-name> ,
S(a,b)
<b-term>
<b-facor>
and
T(b,c)
<b-primary>
<comp-pred>
<exp>
<co-op> =
<term>
<factor>
S.b
T.b
> a 4
<integer>
parse tree
preprocessing
parse tree
parse tree-lqp convertor
S(a,b)
T(b,c) c × π σ
S.b=T.b AND a>4
logic query plan
output
Lqp-pqp convertor
Projection(c)
take care of issues in optimization and security.
physical query plan
In general
a pretty bad
algorithm
Select(S.b=T.b & a>4)
Alg-CrossProd
Machine executable code
ScanTable(S(a,b))
ScanTable(T(b,c))

42. parse tree-lqp convertor
Query Optimization
An input database program P
Prepare a collection A of efficient algorithms for operations in relational algebra;
parser
parse tree
preprocessing
View processing,
Semantic checking
parse tree-lqp convertor
logic query plan
Lqp-pqp convertor
take care of issues in optimization and security.
physical query plan
Machine executable code

43. parse tree-lqp convertor
Query Optimization
An input database program P
Prepare a collection A of efficient algorithms for operations in relational algebra;
parser
View processing,
Semantic checking
parse tree
preprocessing
parse tree
parse tree-lqp convertor
logic query plan
push selections,
group joins
apply logic laws
logic query plan
Lqp-pqp convertor
take care of issues in optimization and security.
physical query plan
Machine executable code

44. parse tree-lqp convertor
Query Optimization
An input database program P
Prepare a collection A of efficient algorithms for operations in relational algebra;
parser
View processing,
Semantic checking
parse tree
preprocessing
parse tree
parse tree-lqp convertor
logic query plan
push selections,
group joins
apply logic laws
logic query plan
reduce the size of
intermediate results
Optimization via logic and size
logic query plan
Lqp-pqp convertor
take care of issues in optimization and security.
physical query plan
Machine executable code

45. parse tree-lqp convertor
Query Optimization
An input database program P
Prepare a collection A of efficient algorithms for operations in relational algebra;
parser
View processing,
Semantic checking
parse tree
preprocessing
parse tree
parse tree-lqp convertor
logic query plan
push selections,
group joins
apply logic laws
logic query plan
reduce the size of
intermediate results
Optimization via logic and size
logic query plan
Lqp-pqp convertor
take care of issues in optimization and security.
physical query plan
choices of algorithms,
data structures, and
computational modes
Optimization via algorithms and cost
Machine executable code

46. parse tree-lqp convertor
Query Optimization
An input database program P
Prepare a collection A of efficient algorithms for operations in relational algebra;
parser
View processing,
Semantic checking
parse tree
preprocessing
parse tree
parse tree-lqp convertor
logic query plan
push selections,
group joins
apply logic laws
logic query plan
reduce the size of
intermediate results
Optimization via logic and size
logic query plan
Lqp-pqp convertor
take care of issues in optimization and security.
physical query plan
choices of algorithms,
data structures, and
computational modes
Optimization via algorithms and cost
Machine executable code