DO YOU LACK STABILITY IN YOUR LIFE? ESPECIALLY WHEN IT COMES TO ORACLE EXECUTION PLANS?

Transcription

1 DO YOU LACK STABILITY IN YOUR LIFE? ESPECIALLY WHEN IT COMES TO ORACLE EXECUTION PLANS? Janis Griffin Senir DBA / Perfrmance Evangelist

2 WHO AM I Senir DBA / Perfrmance Evangelist fr SlarWinds JanisGriffin@slarwindscm Twitter Current 25+ Years in Oracle, SQL Server, ASE, and nw MySQL DBA and Develper Specialize in Perfrmance Tuning Review Database Perfrmance fr Custmers and Prspects Cmmn Questin Hw d I tune it? 2

3 AGENDA Histry f Plan Stability In the beginning Outlines, Prfiles, Patches & Baselines Hw the ptimizer wrks Why & hw d plans change V$SQL_PLAN & V$SQL_SHARED_CURSOR Helps with finding ut the WHY XML Query f clumn Other_XML Which features may impact the plan Adaptive Cursr Sharing SQL Directives & Statistics Feedback Using Baselines, Patches & Prfiles t help stabilize plans Q & A 3

4 QUERY SUDDENLY RUNS SLOWER Specified SQL Statements PROD_STA740 December 19, 2015 t January 17, 2016 Why is this query, which runs nce a day, suddenly taking s lng? 4

5 PLAN REGRESSION Tp Plans fr SQL Statement Change Ntices PROD_STA740 December 19, 2015 t January 17, 2016 Sudden plan change 5

6 IN THE BEGINNING - HISTORY OF PLAN STABILITY Oracle 8 Intrduced cst-based ptimizer Allwed fr Hash jins, Histgrams, Partitining & Parallel queries Required statistics gathering Quickly fund ut that plans culd change ver time Stred Outlines t cntrl plan changes Oracle 10g SQL Prfiles / Tuning Advisr Sub-ptimal executin plans still generated Perfrmance Regressin vertime - N Evlutin DBMS_SQLTUNE Csts $$$ Oracle 11 SQL Patches & SQL Plan Management (Baselines) SQL Patches free bth in Standard r Enterprise Baselines free with Enterprise Oracle 12C Adaptive Optimizer Allws fr autmatic plan evlutin & SPM Evlve Advisr 6

7 OUTLINES & PROFILES Stred Outlines Can freeze a plan fr a specific statement Used when sql changing between a cuple f plans e.g. bind variable peeking Implemented with hints S freeze is nt abslutely guaranteed (e.g. hint uses index but index can be drpped) DBMS_OUTLN / alter sessin set create_stred_utlines = true; SQL Prfiles Created by SQL Tuning Advisr (dbms_sqltune - cst $$$) Similar t Outlines implemented with hints Uses OPT_ESTIMATE hint nt always accurate Tries t imprve cst estimates ver time (factrs 10x estimate may be wrng) Nightly lk at SQLs t find better executin plan 7

8 OUTLINES & PROFILES LIMITATIONS Reactive versus Practive Perfrmance issues have t ccur befre fix Depends n hints t limit ptimizer chices Nt a guaranteed plan when changes happen Can grw stale ver time N evlutin f plans as changes happen Outlines Deprecated Annuncement in 11 But still wrk in 12c Prfiles/Tuning Advisr Cst $$$ 8

9 SQL PATCHES SQL Patches is part f the SQL Repair Advisr (11g) Used after a SQL statement fails with a critical errr Example - index is drpped, the advisr recmmends a patch using anther index DBA can manually add patches utside f SQL Repair Advisr Used t insert hints int a query which can t be changed Useful fr 3 rd party applicatins Uses the functin: dbms_sqldiag_internal.i_create_patch Advantages ver Prfiles & Baselines Advisr is FREE in bth Standard & Enterprise Additins Wrks withut tuning packs Limitatins If patch is used, it s ften frgtten Need t peridically review perfrmance (wn t evlve) Is mre f a wrkarund than a slutin 9

10 SQL PLAN MANAGEMENT (BASELINES) Preventative mechanism fr Plan Stability Optimizer recrds & evaluates executin plans ver time (if run mre than nce) Baselines can evlve vertime fr better perfrmance Preserves perfrmance regardless f changes DBA can verify that nly cmparable r better plans will be used Cmmn Uses f Baselines System & Data changes causing perfrmance regressins Database Upgrades & New Applicatin Installs In 12c Manage SPM Evlve Advisr via OEM r DBMS_AUTO_TASK_ADMIN Still can evlve unaccepted plans manually using DBMS_SPM r OEM 10

11 BASELINE LIMITATIONS Baseline evlutin is dependent n new plan perfrmance Must be >= 1.5x better Significant perfrmance imprvements culd happen > 1x DBA must manually research and evlve these Baselines are created using the signature f the SQL statement Unique SQL identifier generated frm the nrmalized SQL text Uncased & whitespaces remved Culd be wrng plan if same SQL statement is used in different schemas Fr example, missing index in ne schema nt the ther May result in many unaccepted baselines SQL statements using dblinks can t be baselined N remte access 11

12 SOLARWINDS WORLDWIDE, LLC. ALL RIGHTS RESERVED. 12

13 HOW THE OPTIMIZER WORKS Parsed Query (frm Parser) Query Transfrmer rewrites query t be mre efficient Transfrmed Query Estimatr lks at selectivity, cardinality & cst Query + Estimates Data Dictinary Schema Definitin Statistics Plan Generatr creates multiple plans using different access paths & jin types. Plan with lwest cst is chsen Init.ra parameter t cntrl behavir: OPTIMIZER_FEATURES_ENABLED Default Plan sent t Rw Surce Generatr 13

14 EXECUTION PLAN Shw the sequence f peratins perfrmed t run SQL Statement Order f the tables referenced in the statements Access methd fr each table in the statement INDEX INLIST ITERATOR TABLE ACCESS VIEW Jin methd in statement accessing multiple tables HASH JOIN MERGE JOIN NESTED LOOPS Data manipulatins CONCATENATION COUNT FILTER SORT Statistic Cllectrs New in 12C 14

15 12C ADAPTIVE QUERY OPTIMIZER Allws fr run-time adjustments t executin plans Can discver additinal infrmatin Which can lead t better statistics & ptimal plans Adaptive Query Optimizer Adaptive Plans Adaptive Statistics Jin Methds Parallel Distributin Dynamic Statistics Autmatic Reptimizatin Sql Plan Directives 15

16 HOW TO CONTROL & VIEW ADAPTATIONS Init.ra parameters that cntrl Adaptive Plans Name Type Value ptimizer_adaptive_features blean TRUE ptimizer_adaptive_reprting_nly blean FALSE ptimizer_features_enable string ptimizer_dynamic_sampling integer 2 Use DBMS_XPLAN.DISPLAY_CURSOR t view Adaptatins Use frmat parameter +reprt fr testing Wrks with reprting_nly mde select * frm table(dbms_xplan.display_cursr ('&sql_id',&child,frmat=>'+reprt')); Use frmat parameter +adaptive t see all steps ( active / inactive) Including instrumented statistics cllectrs select * frm table(dbms_xplan.display_cursr('&sql_id',&child,frmat=>'+adaptive')); 16

17 ADAPTIVE PLANS SELECT sql_id, child_number, SUBSTR(sql_text, 1,30) sql_text, IS_RESOLVED_ADAPTIVE_PLAN, IS_REOPTIMIZABLE FROM v$sql WHERE sql_text like 'select /* jg */%' ORDER BY sql_id,child_number select /* jg */ p.prduct_name frm rder_items, prduct p where.unit_price = :b1 and.quantity > :b2 and.prduct_id = p.prduct_id; IS_REOPTIMIZABLE is fr next executin Y - the next executin will trigger a reptimizatin R has reptimizatin inf but wn t trigger due t reprting mde N -the child cursr has n reptimizatin inf 17

18 OPTIMIZER_ADAPTIVE_REPORTING_ONLY alter sessin set ptimizer_adaptive_reprting_nly=true; select * frm table(dbms_xplan.display_cursr('8qpakg674n4mz',0,frmat=>'+reprt')); 18

19 ACTUAL ADAPTIVE PLAN Adapted n first executin ; alter sessin set ptimizer_adaptive_reprting_nly=false 19

20 WHY PLANS CHANGES Executin plans can change as underlying inputs t ptimizer change Same Sql Different Schemas Different table sizes / statistics / indexes Same Sql Different Csts Data vlume & Statistic Changes ver time Bind variable types and values Initializatin parameters (set glbally r sessin level) Adaptive Cursr Sharing 11G V$SQL - IS_BIND_SENSITIVE: ptimizer peeked plan may change V$SQL - IS_BIND_AWARE: Y after query has been marked bind sensitive Adaptive Plans, Statistics, & Directives 12C V$SQL_SHARED_CURSOR Can give clues t why plan changed 70 clumns shwing mismatches /differences Hard t view query next slide 20

21 V$SQL_SHARED_CURSOR - SHARED_PROC.SQL DECLARE c NUMBER; cl_cnt NUMBER; cl_rec DBMS_SQL.DESC_TAB; cl_value VARCHAR2(4000); ret_val NUMBER; BEGIN c := dbms_sql.pen_cursr; DBMS_SQL.PARSE(c, SELECT q.sql_text, s.* FROM v$sql_shared_cursr s, v$sql q WHERE s.sql_id = q.sql_id AND s.child_number = q.child_number AND q.sql_id = &1, DBMS_SQL.NATIVE); DBMS_SQL.DESCRIBE_COLUMNS(c, cl_cnt, cl_rec); FOR idx IN 1.. Cl_cnt LOOP DBMS_SQL.DEFINE_COLUMN(c, idx, cl_value, 4000); END LOOP; ret_val := DBMS_SQL.EXECUTE(c); while(dbms_sql.fetch_rows(c) > 0) LOOP FOR idx IN 1.. Cl_cnt LOOP DBMS_SQL.COLUMN_VALUE(c, idx, cl_value); IF cl_rec(idx).cl_name in ( SQL_ID, ADDRESS, CHILD_ADDRESS, CHILD_NUMBER, SQL_TEXT, REASON ) THEN DBMS_OUTPUT.PUT_LINE(RPAD(cl_rec(idx).cl_name, 30) = cl_value); ELSIF cl_value = Y THEN DBMS_OUTPUT.PUT_LINE(RPAD(cl_rec(idx).cl_name, 30) = cl_value); END IF; END LOOP; DBMS_OUTPUT.PUT_LINE( ); END LOOP; DBMS_SQL.CLOSE_CURSOR(C); END; / 21

22 QUERIES WITH MULTIPLE PLANS OPTIMIZER MISMATCH SELECT sql_id, cunt(*) plan_cnt FROM v$sql SELECT /*+ OPT_PARAM('_fix_cntrl :1') */ GROUP_TYPE, BUCKET_START, BUCKET_END, TM_GROUP_TYPE... _fix_cntrl is a hidden parameter fr bugs - see v$system_fix_cntrl r v$sessin_fix_cntrl GROUP BY sql_id having cunt(*) >1 ORDER BY 2 DESC; 22

23 QUERIES WITH MULTIPLE PLANS BIND MISMATCH SELECT cunt(*) child_cnt, m.psitin bind_number, m.max_length, decde(m.datatype,1,'varchar2',2,'number',m.datatype) AS datatype FROM v$sql s, v$sql_bind_metadata m WHERE s.sql_id = '&sql_id' AND s.child_address = m.address grup by m.psitin, m.max_length,decde(m.datatype,1,'varchar2',2,'number',m.datatype) having cunt(*) < &tt_child_cnt rder by 4,1 23

24 EXAMPLE OF ADAPTIVE PLANS Select /* jg */ p.prduct_name frm rder_items, prduct p where.unit_price = :b1 and.quantity > :b2 and.prduct_id = p.prduct_id; 24

25 MY V$SQL_SHARED_CURSOR DECLARE c NUMBER; cl_cnt NUMBER; cl_rec DBMS_SQL.DESC_TAB; cl_value VARCHAR2(4000); ret_val NUMBER; v_sql_id VARCHAR2(100); BEGIN c := dbms_sql.pen_cursr; DBMS_SQL.PARSE(c,'SELECT q.sql_text, s.* FROM v$sql_shared_cursr s, v$sql q WHERE s.sql_id = q.sql_id AND s.child_number = q.child_number', DBMS_SQL.NATIVE); DBMS_SQL.DESCRIBE_COLUMNS(c, cl_cnt, cl_rec); FOR idx IN 1.. Cl_cnt LOOP DBMS_SQL.DEFINE_COLUMN(c, idx, cl_value, 4000); END LOOP; ret_val := DBMS_SQL.EXECUTE(c); while(dbms_sql.fetch_rows(c) > 0) LOOP FOR idx IN 1.. Cl_cnt LOOP DBMS_SQL.COLUMN_VALUE(c, idx, cl_value); IF cl_rec(idx).cl_name in ('SQL_ID') THEN v_sql_id := cl_rec(idx).cl_name ' = ' cl_value; ELSIF cl_value = 'Y' THEN DBMS_OUTPUT.PUT_LINE(v_sql_id ' ' RPAD(cl_rec(idx).cl_name, 30) ' = ' cl_value); END IF; END LOOP; END LOOP; DBMS_SQL.CLOSE_CURSOR(C); END; / 25

26 V$SQLPLAN & DBMS_XPLAN.DISPLAY_CURSOR SELECT /*+ pt_param('parallel_executin_enabled', 'false') */ /* EXEC_FROM_DBMS_XPLAN */ id, parent_id, partitin_id, timestamp, ptimizer, psitin, search_clumns, depth, peratin, ptins, bject_name, bject_wner, bject_type, null as bject_instance, cardinality, bytes, temp_space, cst, i_cst, cpu_cst, time, partitin_start, partitin_stp, bject_nde, ther_tag, distributin, null, access_predicates, filter_predicates, ther, null, null, ther_xml, sql_prfile, sql_plan_baseline, null, null, null, null, null, null, null,null, null, null, null, null, null, null, null, null frm (select /*+ n_merge */ vp.id id, vp.parent_id parent_id, vp.partitin_id, vp.timestamp, vp.ptimizer, vp.search_clumns, vp.depth depth, vp.psitin psitin, vp.peratin peratin, vp.ptins ptins, vp.cst cst, vp.time time, vp.cardinality cardinality, vp.bytes bytes, vp.bject_nde bject_nde, vp.bject_name bject_name, vp.bject_wner bject_wner, vp.bject_type bject_type, null as bject_instance, vp.ther_tag ther_tag, vp.partitin_start partitin_start, vp.partitin_stp partitin_stp, vp.distributin distributin, vp.temp_space temp_space, vp.i_cst i_cst, vp.cpu_cst cpu_cst, vp.filter_predicates filter_predicates, vp.access_predicates access_predicates, vp.ther ther, vp.prjectin prjectin, vp.qblck_name qblck_name, vp.bject_alias bject_alias, vp.ther_xml ther_xml, v$sql.sql_prfile sql_prfile, v$sql.sql_plan_baseline sql_plan_baseline, 0 starts, 0 utrws, 0 crgets, 0 cugets,0 reads,0 writes, 0 etime,0 mem_pt,0 mem_ne, null last_mem_used, null last_mem_usage,0 pt_cnt,0 ne_cnt,0 multi_cnt,0 max_tmp,0 last_tmp frm V$SQL_PLAN vp, v$sql where vp.sql_id = &sql_id and vp.child_number=&child and vp.sql_id = v$sql.sql_id and v$sql.is_bslete = 'N' and v$sql.address = vp.address and v$sql.child_number= &child) rder by id; select * frm table(dbms_xplan.display_cursr( &sql_id, &child_number)); 26

27 V$SQLPLAN & DBMS_XPLAN.DISPLAY_CURSOR CONT. OTHER_XML clumn cntains ntes, peeked binds, hints, & display map infrmatin SELECT /*+ pt_param('parallel_executin_enabled', 'false') */ extractvalue(xmlval, = "sql_prfile"]') sql_prfile, extractvalue(xmlval, = "sql_patch"]') sql_patch, extractvalue(xmlval, = "baseline"]') baseline, extractvalue(xmlval, = "utline"]') utline, extractvalue(xmlval, = "dynamic_sampling"]') dynamic_sampling, extractvalue(xmlval, = "dp"]') dp, extractvalue(xmlval, = "dp_reasn"]') dp_reasn, extractvalue(xmlval, = "pdml_reasn"]') pdml_reasn, extractvalue(xmlval, = "idl_reasn"]') idl_reasn, extractvalue(xmlval, = "queuing_reasn"]') queuing_reasn, extractvalue(xmlval, = "px_in_memry"]') px_in_memry, extractvalue(xmlval, = "px_in_memry_imc"]') px_in_memry_imc, extractvalue(xmlval, = "rw_shipping"]') rw_shipping, extractvalue(xmlval, = "index_size"]') index_size, extractvalue(xmlval, = "result_checksum"]') result_checksum, extractvalue(xmlval, = "cardinality_feedback"]') cardinality_feedback, extractvalue(xmlval, = "perfrmance_feedback"]') perfrmance_feedback, extractvalue(xmlval, = "xml_subptimal"]') xml_subptimal, extractvalue(xmlval, = "adaptive_plan"]') adaptive_plan, extractvalue(xmlval, '/*/spd/cu') spd_cu, extractvalue(xmlval, = "gtt_sessin_st"]') gtt_sessin_st, = "plan_hash"]') plan_hash frm (select xmltype(replace(ther_xml,'''','"')) xmlval frm v$sql_plan where sql_id = '&sqlid' and child_number=&child and ther_xml is nt null); 27

28 WHICH FEATURES MAY IMPACT THE PLAN Bind Variable Peeking / Adaptive Cursr Sharing Example First ran with :P1=10 28

29 BIND VARIABLE PEEKING / ADAPTIVE CURSOR SHARING 1 st run with :p1=10 Changed after 2 nd executin f :p1=40 29

30 BIND VARIABLE PEEKING / ADAPTIVE CURSOR SHARING :P SELECT * FROM TABLE (DBMS_SQLTUNE.EXTRACT_BINDS ('BEDA0C C989D000101C C10B')); 30

31 DYNAMIC STATISTICS (DYNAMIC SAMPLING IN 9.2) Missing Statistics Stale Statistics Insufficient Statistics Estimates ver 6X ff! Parallel Executin SQL Plan Directives Ntes: Parse time takes lnger. Results are persisted & used elsewhere 31

32 STATISTICS FEEDBACK Estimated cardinalities can be incrrect fr many reasns missing statistics, inaccurate statistics, r cmplex predicates After 1st executin, estimates are cmpared with actual rws If they differ significantly, ptimizer stres crrect estimates fr future use Statistics feedback = OPT_ESTIMATE hints in V$SQL_REOPTIMIZATION_HINTS Can create a SQL PLAN DIRECTIVE fr ther SQL statements They benefit frm infrmatin btained during initial executin 32

33 STATISTICS FEEDBACK select * frm table(dbms_xplan.display_cursor(format=>'allstats LAST')); 33

34 STATISTICS FEEDBACK ANOTHER EXAMPLE 34

35 SQL PLAN DIRECTIVES Are additinal Instructins fr missing clumn grup statistics r histgrams Dynamic sampling perfrmed n directive Until statistics are gathered fr the clumn grup (e.g. City / State / Cuntry) Nt tied t a specific sql statement defined n a query expressin Can be used by similar queries Are created in shared_pl & peridically written t SYSAUX tablespace DBA_SQL_PLAN_DIRECTIVES DBA_SQL_PLAN_DIR_OBJECTS Use DBMS_STATS extended functins & prcedures CREATE_EXTENDED_STATS SHOW_EXTENDED_STATS_NAME DROP_EXENTED_STATS 35

36 SQL PLAN DIRECTIVES CONT. SELECT TO_CHAR(d.directive_id) dir_id,.wner,.bject_name,.subbject_name cl_name,.bject_type, d.type,d.state,d.reasn FROM dba_sql_plan_directives d, dba_sql_plan_dir_bjects WHERE d.directive_id =.directive_id AND.wner IN ( DPA') ORDER BY 1,2,3,4,5; SELECT sum(sw.qp)/100.0 FROM CONSW_4 SW, CONEV_4 EV where SW.KEEQ=EV.ID and lwer(ev.name)='direct path read' and SW.D > :p1; 36

37 HOW TO MANAGE SQL PLAN DIRECTIVES Use DBMS_SPD package t manage Can t manually create directives Name P / F Task ALTER_SQL_PLAN_DIRECTIVE P Changes either STATE r AUTO_DROP DROP_SQL_PLAN_DIRECTIVE P Drps SQL Plan Directive (SPD) FLUSH_SQL_PLAN_DIRECTIVE P Flushes SQL Plan Directives ut f SGA CREATE_STGTAB_DIRECTIVE P Staging table fr exprting SPDs PACK_STGTAB_DIRECTIVE F Exprts SPDs in t Staging table UNPACK_STGTAB_DIRECTIVE F Imprts SPDs frm Staging table GET_PREFS F Get setting fr SPD_RETENTION_WEEKS SET_PREFS P Sets SPD_RETENTION_WEEKS (default set t 53 weeks) TRANSFER_SPD_FOR_DP P Undcumented 37

38 DON T WANT ANY DIRECTIVES Drp all existing SPD Alter system / sessin set _ptimizer_dsdir_usage_cntrl =0; Nt Recmmended Tip: Mnitr SQL DIRECTIVES and their states clsely Create extended statistics Remve directives when supprted by valid statistics. 38

39 12.2 OPTIMIZER CHANGES New init.ra parameters OPTIMIZER_ADAPTIVE_PLANS (Default = TRUE) Adaptive jins Bitmap pruning Parallel distributin methd OPTIMIZER_ADAPTIVE_STATISTICS (Default = False) SQL Plan Directives (SPDs) fr query ptimizatin Statistics feedback (fr jins nly) Adaptive dynamic sampling fr parallel queries Perfrmance feedback Obslete OPTIMIZER_ADAPTIVE_FEATURES 2017 SlarWinds Wrldwide, LLC. All rights reserved.

40 12.2 OPTIMIZER CHANGES SQL Plan Directives Cntrl f Aut Creatin f Clumn Grup Statistics New DBMS_STATS preference AUTO_STAT_EXTENSIONS (DEFAULT=OFF) EXEC DBMS_STATS.SET_GLOBAL_PREFS('AUTO_STAT_EXTENSIONS','ON') Can view in DBA_STAT_EXTENSIONS select wner, table_name, extensin, extensin_name frm dba_stat_extensins where creatr = 'SYSTEM' rder by wner,table_name,extensin_name; 2017 SlarWinds Wrldwide, LLC. All rights reserved.

41 DBMS_SPD Example f drpping all directives fr SOE user EXEC DBMS_SPD. FLUSH_SQL_PLAN_DIRECTIVE; BEGIN FOR get_rec in (SELECT distinct TO_CHAR(d.directive_id) dir_id FROM dba_sql_plan_directives d, dba_sql_plan_dir_bjects WHERE d.directive_id =.directive_id AND.wner in ('SOE')) LOOP DBMS_SPD.DROP_SQL_PLAN_DIRECTIVE(get_rec.dir_id); end lp; end; / cmmit; 39

42 HOW TO STABILIZE PLANS Baselines Prfiles Patches 42

43 SQL PLAN MANAGEMENT (BASELINES) 11g feature helps stp perfrmance regressin via plan changes Uses baselines t guarantee nly better plans are used 12c SPM evlve advisr is an Aut Task (SYS_AUTO_SPM_EVOLVE_TASK) Runs nightly in maintenance windw Autmatically runs the evlve prcess fr nn-accepted plans in SPM DBA views results f nightly task using DBMS_SPM.REPORT_AUTO_EVOLVE_TASK Can Manage via OEM r DBMS_AUTO_TASK_ADMIN Still can manually evlve an unaccepted plan using OEM r DBMS_SPM DBMS_SPM.EVOLVE_SQL_PLAN_BASELINE has been deprecated in 12c var task varchar2(1000); var evlve varchar2(100); var imple varchar2(1000); var rpt clb; exec :task := DBMS_SPM.CREATE_EVOLVE_TASK(sql_handle=>'&sql_handle'); exec :evlve := DBMS_SPM.EXECUTE_EVOLVE_TASK(task_name=>:task); exec :imple :=DBMS_SPM.IMPLEMENT_EVOLVE_TASK(task_name=>:task,FORCE=>true); exec :rpt := DBMS_SPM.REPORT_EVOLVE_TASK(task_name=>:task,type=>'TEXT', executin_name=>:evlve); print 43

44 SQL PLAN MANAGEMENT (BASELINES) 44

45 EXAMPLE PRODUCT QUERY SELECT prducts.prduct_id, prduct_name, prduct_descriptin, categry_id, weight_class, warranty_perid, supplier_id, prduct_status, list_price, min_price, catalg_url, quantity_n_hand FROM prducts, inventries WHERE prducts.categry_id = :b3 AND inventries.prduct_id = prducts.prduct_id AND inventries.warehuse_id = :b2 AND rwnum < :b1 SELECT sql_handle, plan_name, sql_text, enabled, accepted, fixed frm dba_sql_plan_baselines; SET SERVEROUTPUT ON LONG DECLARE rpt clb; BEGIN rpt := DBMS_SPM.EVOLVE_SQL_PLAN_BASELINE( sql_handle => 'SYS_SQL_fdf0214a24814e13'); DBMS_OUTPUT.PUT_LINE(rpt); END; 45

46 EXAMPLE BASELINE / EVOLVE 46

47 EXAMPLE HIGH COST select * frm table(dbms_xplan.display_sql_plan_baseline(sql_handle=>'sys_sql_fdf0214a24814e13',plan_name=>'sys_sql_plan_24814e132c1c9d7b')) 45

48 EXAMPLE FORCE PLAN Frce Evlutin f new baseline var task varchar2(1000); var evlve varchar2(100); var imple varchar2(1000); var rpt clb; exec :task := DBMS_SPM.CREATE_EVOLVE_TASK(sql_handle=>'&sql_handle'); exec :evlve := DBMS_SPM.EXECUTE_EVOLVE_TASK(task_name=>:task); exec :imple :=DBMS_SPM.IMPLEMENT_EVOLVE_TASK(task_name=>:task,FORCE=>true); exec :rpt := DBMS_SPM.REPORT_EVOLVE_TASK(task_name=>:task,type=>'TEXT', executin_name=>:evlve); print Disable Old Plan var ret number exec :ret := DBMS_SPM.ALTER_SQL_PLAN_BASELINE( - sql_handle=>'sys_sql_fdf0214a24814e13', - plan_name=>'sys_sql_plan_24814e132c1c9d7b', - attribute_name=> ENABLED', - attribute_value=> NO'); 48

49 EXAMPLE BETTER PERFORMANCE Frced New Baseline 49

50 BASELINE TIPS If yu can hint it, baseline it (per Tm Kyte) Alternative t using hints 3rd Party Sftware can t mdify cde Hints difficult t manage ver time Once added, usually frgtten abut 50

51 SQL PATCHES Can change the executin plans by supplying hints 3rd Party Sftware can t mdify cde Wrks in Standard & Enterprise editins Needs grant execute n sys.dbms_sqldiag_internal -- Cmmand t drp patch if it already exists exec DBMS_SQLDIAG.DROP_SQL_PATCH('EMP_PATCH'); -- Cmmands t create patch begin sys.dbms_sqldiag_internal.i_create_patch( sql_text => 'select cunt(*), max(empn) frm emp where deptn = :deptn', hint_text => 'DYNAMIC_SAMPLING(4), name => 'EMP_PATCH'); end; / 51

52 SQL PATCHES ANOTHER EXAMPLE begin sys.dbms_sqldiag_internal.i_create_patch( sql_text => 'select e.empn EOD, e.ename "Emplyee_name", d.dname "Department",' ' e.hiredate "Date_Hired" frm emp e, dept d where d.deptn = :p1' ' and e.deptn = d.deptn', hint_text => 'BIND_AWARE', name => 'EMP_DEPTNO'); end; / NOTE - SQL patch "EMP_DEPTNO" used fr this statement 52

53 SQL PROFILES & TUNING ADVISOR Tuning Advisr runs nightly DBMS_AUTO_SQLTUNE Can be cnfigured t autmatically implement SQL Prfiles Nt recmmended Can run manually fr advice fr ne r mre SQL statements DECLARE l_sql_tune_task_id VARCHAR2(100); BEGIN l_sql_tune_task_id := DBMS_SQLTUNE.create_tuning_task ( sql_id => '&sql_id', scpe => DBMS_SQLTUNE.scpe_cmprehensive, time_limit => 60, task_name => '&sql_id', descriptin => 'Tuning task fr class registratin query'); DBMS_OUTPUT.put_line('l_sql_tune_task_id: ' l_sql_tune_task_id); END; / EXEC DBMS_SQLTUNE.execute_tuning_task(task_name => '&sql_id'); 53

54 SQL PROFILES & TUNING ADVISOR Query t reprt advice VARIABLE aut_rpt CLOB; BEGIN :aut_rpt :=DBMS_SQLTUNE.REPORT_AUTO_TUNING_TASK ( begin_exec => NULL, end_exec => NULL, type => 'TEXT', level => 'TYPICAL', sectin => 'ALL, bject_id => NULL, result_limit => NULL); END; / PRINT :aut_rpt 54

55 SQL PROFILES MANUAL SETUP Select * frm table (dbms_xplan.display_cursr( &sql_id,&child, ADVANCED )); 55

56 SQL PROFILES MANUAL SETUP DECLARE sqlt clb; BEGIN sqlt := q'!select sal salary, e.empn EOD, e.ename "Emplyee_name", d.dname "Department", e.hiredate "Date_Hired" frm emp e, dept d where d.deptn = :p1 and e.deptn = d.deptnand sal > :p2 rder by sal desc!'; dbms_sqltune.imprt_sql_prfile( sql_text => sqlt, name => 'SP_EMPHASH', prfile => sqlprf_attr(q'!pq_distribute(@"sel$1" "E"@"SEL$1" BROADCAST NONE)!', q'!use_hash(@"sel$1" "E"@"SEL$1")!', q'!leading(@"sel$1" "D"@"SEL$1" "E"@"SEL$1")!', q'!full(@"sel$1" "E"@"SEL$1")!', q'!full(@"sel$1" "D"@"SEL$1")!', q'!outline_leaf(@"sel$1")!', q'!all_rows!', q'!db_version(' ')!', q'!optimizer_features_enable(' ')!', q'!ignore_optim_embedded_hints!'), frce_match => true ); END; / 56

57 SUMMARY Oracle has many ways t imprve Plan Stability Almst t many It can be cnfusing at times Outlines, Prfiles, Patches & Baselines Plans change fr many reasns Data grws, system changes, stale statisics Oracle features such as SQL Directives, Adaptive Cursr Sharing, etc V$SQL_PLAN & V$SQL_SHARED_CURSOR helps with finding ut the WHY Dn t frget abut XML Query f clumn Other_XML Mnitr the features that may impact plans dba_sql_plan_directives, dba_sql_plan_dir_bjects, & v$sql_retimizatin_hints Cnsider using Baselines, Patches & Prfile t help stabilize plans Q & A 55

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