jonathan lewis eoug jun 2000 execution plans agenda what are execution plans where do you find...

Jonathan LewisEOUG Jun 2000

Execution Plans

Agenda

• What are execution plans

• Where do you find execution plans

• Key mechanisms of execution

• Understanding a complex plan

• Conclusion


Execution Plans

What are execution plans

Show me

all clients accounts

which are

holding at least one position

and have no unsettled positions


Execution Plans


Select * from accounts awhere exists ( select null from holdings h1

where h1.account = a.account and av_qty != 0

)and not exists (select null from holdings h2

where h2.account = a.acount and unset_qty = 0

)


Execution Plans


SELECT STATEMENT

FILTER

TABLE ACCESS FULL ACCOUNT

TABLE ACCESS BY ROWID HOLDING

INDEX RANGE SCAN HOLD_IX1 NON-UNIQUE

TABLE ACCESS BY ROWID HOLDING

INDEX RANGE SCAN HOLD_IX1 NON-UNIQUE

Execution Plans

Where do plans come from ?

select ep1.v1, ep2.v2, ep3.n2

from ep3, ep2, ep1

where (

ep3.v1 = 'TV Region1'

or ep3.v2 = 'Newspaper2'

)

and ep2.n1 = ep3.n1

and ep2.n2 = ep3.n2

and ep1.n1 = ep2.n1;


Execution Plans

Autotrace

• SQL*Plus

• set autotrace on

• set autotrace on explain

• set autotrace traceonly explain

• set autotrace traceonly statistics

Execution Plans

Autotrace

0 SELECT STATEMENT Optimizer=FIRST_ROWS (c,c,b)

1 0 HASH JOIN (c,c,b)

2 1 TABLE ACCESS (FULL) OF 'EP1' (c,c,b)

3 1 NESTED LOOPS (c,c,b)

4 3 TABLE ACCESS (BY INDEX ROWID) OF 'EP3' (c,c,b)

5 4 BITMAP CONVERSION (TO ROWIDS)

6 5 BITMAP OR

7 6 BITMAP INDEX (SINGLE VALUE) OF 'EP3_BI1'

8 6 BITMAP INDEX (SINGLE VALUE) OF 'EP3_BI2'

9 3 TABLE ACCESS (BY INDEX ROWID) OF 'EP2' (c,c,b)

10 9 INDEX (UNIQUE SCAN) OF 'EP2_PK' (UNIQUE)


Execution Plans

Explain Plan

explain plan

set statement_id = userenv(‘sessionid’)

for

sql_statement;

select from plan_table

start with

connect by

order by

Execution Plans

Explain Plan

0 402 SELECT STATEMENT (first_rows) (c,c,b)

1 0 1 HASH JOIN (c,c,b)

2 1 1 3 TABLE ACCESS (analyzed) EP1 (full) (c,c,b)

3 1 2 NESTED LOOPS (c,c,b)

4 3 1 1 TABLE ACCESS (analyzed) EP3 (by index rowid) (c,c,b)

5 4 1 BITMAP CONVERSION (to rowids)

6 5 1 BITMAP OR

7 6 1 BITMAP INDEX EP3_BI1 (single value)

8 6 2 BITMAP INDEX EP3_BI2 (single value)

9 3 2 2 TABLE ACCESS (analyzed) EP2 (by index rowid) (c,c,b)

10 9 1 INDEX (analyzed) UNIQUE EP2_PK (unique scan)


Execution Plans

tkprof

alter session set sql_trace true;

tkprof {file stem} {file stem} \

explain=userid/password \

sort=\(options\)

Execution Plans

tkprof (1)

301 HASH JOIN

200 TABLE ACCESS FULL EP1

303 NESTED LOOPS

304 TABLE ACCESS BY INDEX ROWID EP3

304 BITMAP CONVERSION TO ROWIDS

2 BITMAP OR

2 BITMAP INDEX SINGLE VALUE

2 BITMAP INDEX SINGLE VALUE

303 TABLE ACCESS BY INDEX ROWID EP2

606 INDEX UNIQUE SCAN (object id 21464)

Execution Plans

tkprof (2)

0 SELECT STATEMENT GOAL: HINT: FIRST_ROWS

301 HASH JOIN

200 TABLE ACCESS GOAL: ANALYZED (FULL) OF 'EP1'

303 NESTED LOOPS

304 TABLE ACCESS GOAL: ANA (BY IND RID) OF 'EP3'

304 BITMAP CONVERSION (TO ROWIDS)

2 BITMAP OR

2 BITMAP INDEX (SINGLE VALUE) OF 'EP3_BI1'

2 BITMAP INDEX (SINGLE VALUE) OF 'EP3_BI2'

303 TABLE ACCESS GOAL: ANA (BY IND RID) OF 'EP2'

606 INDEX GOAL: ANA (UNIQ SC) OF 'EP2_PK' (UNIQ)

Execution Plans

Trace file

id=1 cnt=301 pid=0 pos=0 obj=0 op='HASH JOIN '

id=2 cnt=200 pid=1 pos=1 obj=21461 op='TABLE ACCESS FULL EP1 '

id=3 cnt=303 pid=1 pos=2 obj=0 op='NESTED LOOPS '

id=4 cnt=304 pid=3 pos=1 obj=21465 op='TABLE ACCESS BY IND RID EP3 '

id=5 cnt=304 pid=4 pos=1 obj=0 op='BITMAP CONVERSION TO ROWIDS '

id=6 cnt=2 pid=5 pos=1 obj=0 op='BITMAP OR '

id=7 cnt=2 pid=6 pos=1 obj=21466 op='BITMAP INDEX SINGLE VALUE '

id=8 cnt=2 pid=6 pos=2 obj=21467 op='BITMAP INDEX SINGLE VALUE '

id=9 cnt=303 pid=3 pos=2 obj=21463 op='TABLE ACCESS BY IND RID EP2 '

id=10 cnt=606 pid=9 pos=1 obj=21464 op='INDEX UNIQUE SCAN '


Execution Plans

Key mechanisms of execution

• Data access methods

• Data manipulation methods


Execution Plans

Data access

select * from dept

where dname = 'SALES';

TABLE ACCESS FULL DEPT


Execution Plans

Data access

select empno from emp

where mgr = 7698;

INDEX RANGE SCAN NON-UNIQUE EMP_FK_MGR

The index is (mgr,empno)


Execution Plans

Parent and Child

select * from dept

where deptno = 10;

Id Pid Plan

1 0 TABLE ACCESS BY ROWID DEPT

2 1 INDEX UNIQUE SCAN UNIQUE DPT_PK


Execution Plans

Parent, child, and grandchild

select * from emp

where deptno = 10;

IdPid Plan

1 0 TABLE ACCESS BY ROWID EMP

2 1 BITMAP CONVERSION TO ROWIDS

3 2 BITMAP INDEX SINGLE VALUE EMP_FK_DPT


Execution Plans

Parent with two children

select *

from emp

where job='SALESMAN'

and sal=1250;

IdPid Pos Plan

1 0 1 TABLE ACCESS BY ROWID EMP

2 1 1 AND-EQUAL

3 2 1 INDEX RANGE SCAN NON-UNIQUE EMP_JOB

4 2 2 INDEX RANGE SCAN NON-UNIQUE EMP_SAL


Execution Plans

Mechanisms: Data handling

select

max(sal), count(*)

from emp;

SORT AGGREGATE

TABLE ACCESS FULL EMP


Execution Plans


select deptno,max(sal)

from empgroup by deptno;

SORT GROUP BY



Execution Plans


select deptno,max(sal)

from empgroup by deptno;

SORT GROUP BY (NOSORT)

TABLE ACCESS BY ROWID EMP

INDEX RANGE SCAN NON-UNIQUE EMP_FK_DP


Execution Plans


select max(empno) from emp

where mgr = 7698;

The index is emp_fk_mgr (mgr,empno)

sort (aggregate)

first row

index (range scan (min/max)) of emp_fk_mgr


Execution Plans


select deptno,max(sal)from empgroup by deptnohaving max(sal) > 3000;

FILTER

SORT GROUP BY



Execution Plans


select mgr,count(*)from emp where job = 'SALESMAN'group by mgrorder by count(*) desc;

SORT ORDER BY

SORT GROUP BY


INDEX RANGE SCAN NON-UNIQUE EMP_FK_JOB


Execution Plans


select * from emp where job='SALESMAN' or deptno = 10;

CONCATENATION


BITMAP CONVERSION TO ROWIDS

BITMAP INDEX SINGLE VALUE EMP_FK_DPT




Execution Plans



CONCATENATION




Execution Plans



CONCATENATION


BITMAP CONVERSION TO ROWIDS

BITMAP INDEX SINGLE VALUE EMP_FK_DPT



Execution Plans



CONCATENATION





Execution Plans



Id Pid Ps Plan

1 0 1 CONCATENATION


3 2 1 BITMAP CONVERSION TO ROWIDS

4 3 1 BITMAP INDEX SINGLE VALUE EMP_FK_DPT


6 5 1 INDEX RANGE SCAN NON-UNIQUE EMP_FK_JOB


Execution Plans


select * from emp where job='SALESMAN' or job = 'CLERK'

INLIST ITERATOR




Execution Plans


select * from emp where exists (

select null from projects prjwhere prj.empno = emp.empnoand prj.date_completed is null

)

FILTER


TABLE ACCESS BY ROWID PROJECTS

INDEX RANGE SCAN NON-UNIQUE PRJ_FK_EMP


Execution Plans

Mechanisms: Joins

• Nested Loops

• Sort Merge

• Hash


Execution Plans

Mechanisms: Nested Loop

Nested Loops

[The first set of data]

[The second set of data]


Execution Plans


Nested Loops

Table scan FULL the red pack

Table scan FULL the blue pack


Execution Plans


Nested Loops

Table access by rowid DEPT

Index unique scan DPT_PK

Table access by rowid EMP

Index range scan EMP_FK_DPT


Execution Plans

Mechanisms: Sort Merge

Merge Join

[The first sorted set of data]

[The second sorted set of data]


Execution Plans


Merge Join

Sort join

Table access full DEPT

Sort join

Table access full EMP


Execution Plans


Merge Join

Index Range Scan DPT_IDX

Sort join

Table access full EMP


Execution Plans

Mechanisms: Hash

Hash




Execution Plans

Mechanisms: Hash

Hash

Table access FULL DEPT

Table access FULL EMP


Execution Plans

Understanding a complex plan

Nested Loops




Execution Plans


Nested Loops






Execution Plans


Table access by rowid SALGRADE

Index range scan SAL_PK


Execution Plans


Nested Loops

Nested Loops








Execution Plans


Nested Loops

Table access by rowid REGION

Index unique scan REG_PK


Index unique scan DPT_FK_REG


Execution Plans


Nested Loops

Nested Loops

Nested Loops

Table access by rowid REGION

Index unique scan REG_PK


Index unique scan DPT_FK_REG






Execution Plans


Hash




Execution Plans


Hash

Table scan full Medium_table

Table scan full Large_table


Execution Plans


Table scan full Small_table


Execution Plans


Hash

Hash





Execution Plans


Hash


Hash



Execution Plans

Explain Plan

SELECT STATEMENT (first_rows)

HASH JOIN

TABLE ACCESS (analyzed) EP1 (full)

NESTED LOOPS

TABLE ACCESS (analyzed) EP3 (by index rowid)

BITMAP CONVERSION (to rowids)

BITMAP OR

BITMAP INDEX EP3_BI1 (single value)



INDEX (analyzed) UNIQUE EP2_PK (unique scan)

Execution Plans

Explain Plan - top down


HASH JOIN


NESTED LOOPS



BITMAP OR





Execution Plans

Explain Plan

NESTED LOOPS



BITMAP OR





Execution Plans

Explain Plan



BITMAP OR



Execution Plans

Explain Plan


HASH JOIN


NESTED LOOPS



BITMAP OR





Execution Plans

Explain Plan - Bottom up


HASH JOIN


NESTED LOOPS



BITMAP OR





Execution Plans

Explain Plan


HASH JOIN


NESTED LOOPS



BITMAP OR






Execution Plans

Conclusion

• Execution plans are important

• How much effort do you take

• Break complex plans down

jonathan lewis eoug jun 2000 execution plans agenda what are execution plans where do you find...

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