zen and the art ofSQL optimization

Karen Morton

Simplicity

“Make everything as simple as possible but no simpler.

”— Albert Einstein

— Alan Watts

“Normally, we do not so much look at things as overlook them.”

simplevs

simple-minded

Oracle 9.2.0.6

SELECT to_char( to_date(:B1,‘DD-MON-YYYY’)+1,

‘DD-MON-YYYY’)

FROM dual;

What about its effect?

32.9%% of total R

1,087,770# of executions

3,263,033# of LIOs

v_date_str := to_char(

to_date( :B1,‘DD-MON-YYYY’ ) + 1, ‘DD-MON-YYYY’ ) ;

Focus

ETCIBMVIPNASAFBI

ETCIBMVIPNASAFBI

SELECT rowid, load_no, load_status,manifest_no, manifest_date

FROM cs_loads WHERE load_no = 552888 ;

VARCHAR2(15)

SELECT rowid, load_no, load_status,manifest_no, manifest_date

FROM cs_loads WHERE load_no = 552888 ;

datatype mismatch causes FULL SCAN

SELECT rowid, load_no, load_status,manifest_no, manifest_date

FROM cs_loads WHERE load_no =‘552888’;

SELECT rowid, load_no, load_status,manifest_no, manifest_date

FROM cs_loads WHERE load_no = :B1 ;

Keys to Optimizing SQL

Tune the question,not the query.

What output shouldthe query provide?

What special conditionsneed to be handled?

“If you don’t know where you are going, you’ll end up somewhere else.” — Yogi Berra

Reduce.Reuse.

Decrease rowsource sizes quickly

Access objects onceand reuse the result set

“Not enough gets said

about the importance

of abandoning crap.” - Ira Glass

Practice.

Never stop learning

Stay connected

Think in sets

TestTestTest

(then test again)

“Practice, practice, practice.Until it becomes your practice.”

— Unknown

GoingZen

1

SELECT invoice_id, distribution_line_number FROM ap.ap_invoice_distributions_all ap2 WHERE ap2.project_id > 0 AND ap2.pa_addition_flag = 'T' MINUS SELECT invoice_id, distribution_line_number FROM ap.ap_invoice_distributions_all ap, pa.pa_cost_distribution_lines_all pa WHERE ap.project_id > 0 AND ap.pa_addition_flag = 'T' AND pa.system_reference2 IS NOT NULL AND TO_NUMBER(pa.system_reference2) = ap.invoice_id AND TO_NUMBER(pa.system_reference3) = ap.distribution_line_number ORDER BY invoice_id;

Elapsed Time LIO Blocks PIO Blocks Total Rows------------ ---------- ---------- ---------- 00:00:20.09 60,941 57,116 6

SELECT invoice_id, distribution_line_number FROM (SELECT invoice_id, distribution_line_number, system_reference2, system_reference3 FROM ap.ap_invoice_distributions_all ap, (SELECT TO_NUMBER(system_reference2)

system_reference2, TO_NUMBER(system_reference3) system_reference3 FROM pa.pa_cost_distribution_lines_all WHERE system_reference2 IS NOT NULL) WHERE system_reference2 (+) = ap.invoice_id AND system_reference3 (+) = ap.distribution_line_number AND ap.project_id > 0 AND ap.pa_addition_flag = 'T' ) WHERE system_reference2 IS NULL AND system_reference3 IS NULL ORDER BY invoice_id;

Elapsed Time LIO Blocks PIO Blocks Total Rows------------ ---------- ---------- ---------- 00:00:03.09 1,824 453 6

2

SELECT t.* FROM RMS.tasks t, RMS.status s WHERE t.status_id = s.id AND (EXISTS ( SELECT null FROM RMS.tasks ta, RMS.resources r

WHERE t.id = ta.parent_task_id AND ta.project_code = :p AND ta.task_type_code = 'A' AND ta.resource_id = r.id AND r.reporting_id = :r )

OR (t.project_code = :p AND t.task_type_code = 'T') );

Elapsed Time LIO Blocks PIO Blocks Total Rows------------ ---------- ---------- ---------- 00:00:09.50 287,330 992 3

SELECT t.* FROM RMS.tasks t, RMS.status s WHERE t.status_id = s.id AND EXISTS

(SELECT null FROM RMS.tasks ta,RMS.resources r WHERE t.id = ta.parent_task_id AND ta.project_code = :p

AND ta.task_type_code = 'A' AND ta.resource_id = r.id AND r.reporting_id = :r )

UNIONSELECT t.* FROM RMS.tasks t, RMS.status s WHERE t.status_id = s.id AND t.id IN

(SELECT t.parent_task_id FROM RMS.tasks t, RMS.status s WHERE t.status_id = s.id AND

EXISTS (SELECT null FROM RMS.tasks ta, RMS.resources r WHERE t.id = ta.parent_task_id AND ta.project_code = :p AND ta.task_type_code = 'A' AND ta.resource_id = r.id AND r.reporting_id = :r );

Elapsed Time LIO Blocks PIO Blocks Total Rows------------ ---------- ---------- ---------- 00:00:00.01 128 0 3

3

SELECT J.emplid, J.empl_rcd, J.effdt, J.effseq FROM PS_JOB J WHERE J.effdt = (SELECT MAX(effdt) FROM PS_JOB WHERE emplid = J.emplid AND empl_rcd = J.empl_rcd AND effdt <= SYSDATE ) AND J. effseq = (SELECT MAX(effseq) FROM PS_JOB WHERE emplid = J.emplid AND empl_rcd = J.empl_rcd AND effdt = J.effdt ) ;

Elapsed Time LIO Blocks PIO Blocks Total Rows------------ ---------- ---------- ---------- 00:00:08.04 337,908 0 30,107

SELECT J.emplid, J.empl_rcd, J.effdt, J.effseq FROM (SELECT J.emplid, J.empl_rcd, J.effdt, J.effseq, MAX(J.effdt)

OVER (PARTITION BY J.emplid, J.empl_rcd ) max_effdt, LAST_VALUE(J.effseq) OVER (PARTITION BY J.emplid,

J.empl_rcd ORDER BY J.efdt, J.effseq ROWS BETWEEN CURRENT ROW AND

UNBOUNDED FOLLOWING ) max_effseq FROM PS_JOB J WHERE J.effdt <= SYSDATE ) J

WHERE J.effdt = J.max_effdt AND J.effseq = J.max_effseq;

Elapsed Time LIO Blocks PIO Blocks Total Rows------------ ---------- ---------- ---------- 00:00:00.44 1,009 0 30,107

4

SELECT utrsotp_desc FROM utrsotp, ucbsvco WHERE ucbsvco_sotp_code = utrsotp_code AND ucbsvco_dispatch_date = (SELECT MAX(ucbsvco_dispatch_date) FROM ucbsvco WHERE ucbsvco_cust_code = 1320908 AND ucbsvco_prem_code = '507601' AND ucbsvco_stus_code = 'C' AND ucbsvco_dispatch_ind IS NOT NULL) AND ucbsvco_stus_code = 'C' AND ucbsvco_dispatch_ind IS NOT NULL

Elapsed Time LIO Blocks PIO Blocks Total Rows------------ ---------- ---------- ---------- 00:00:20.16 106,693 0 1

SELECT utrsotp_desc FROM utrsotp, (SELECT ucbsvco_sotp_code, ucbsvco_dispatch_date, MAX(ucbsvco_dispatch_date) OVER(PARTITION BY

ucbsvco_cust_code, ucbsvco_prem_code) max_dispatch_dt

FROM ucbsvco WHERE ucbsvco_cust_code = 1320908 AND ucbsvco_prem_code = '507601' AND ucbsvco_stus_code = 'C' AND ucbsvco_dispatch_ind IS NOT NULL) svco WHERE svco.ucbsvco_dispatch_date = svco.max_dispatch_dt AND svco.ucbsvco_sotp_code = utrsotp_code

Elapsed Time LIO Blocks PIO Blocks Total Rows------------ ---------- ---------- ---------- 00:00:00.18 15 0 1

Simplicity is powerful…

…but it is neithersimple nor easy to

achieve.

It is obtained through the careful

reduction of the nonessential.

While simplicityis the goal…

…it is possible tobe “too simple.”

Your job is to findthe balance mostappropriate toyour situation.

Thank You

http://www.method-r.com

http://karenmorton.blogspot.com

karen.morton@method-r.com