dbms xplan - Oracle database internals by Riyaj · PDF filedbms_xplan: A Swiss army knife for...

dbms_xplan: A Swiss army knife for performance engineers

Sahil Thapar Riyaj Shamsudeen

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Disclaimer

These slides and materials represent the work and opinions of the author and do not constitute official positions of my current or past employer or any other organization. This material has been peer reviewed, but author assume no responsibility whatsoever for the test cases.

If you corrupt your databases by running my scripts, you are solely responsible for that.

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Options

EXPLAIN PLAN (Version 7 or older)

AUTOTRACE (

Version 8i +)

SQL_TRACE (Version 7)

DBMS_XPLAN

Estimated, not always reliable

Actual plan; but must enable trace before the run.

Actual plan, after the run, always available.

Actual plan, buggy.

PARSING IN CURSOR #1844674 len=1000 dep=0 uid=173 oct=3 lid=173 tim=7861072491388 hv=2701626457 ad='498d8f1d0' sqlid='9sup9gfhhg32t'

SELECT RECID, TABLENAME, PROJECT_NUMBER, PROJECT_NAME, CARRYING_OUT_ORGANIZATION, ...FROM ( SELECT STGTBL_RECID

... WHERE PROCESSED_FLAG='U' ) ORDER BY TABLENAME, CREATION_DATE PARSE:#1844674:c=10000,e=10162,p=0,cr=0,cu=0,mis=1,r=0,dep=0,og=1,plh=3298327531,tim=78610

72491386 EXEC:#1844674:c=0,e=139,p=0,cr=0,cu=0,mis=0,r=0,dep=0,og=1,plh=3298327531,tim=786107249172

3 EXEC:#1844674:c=0,e=139,p=0,cr=0,cu=0,mis=0,r=0,dep=0,og=1,plh=3298327531,tim=7861072491723

.. WAIT #1844674: nam='Disk file operations I/O' ela= 2013 FileOperation=2 fileno=811

filetype=2 obj#=706379 tim=786107 FETCH#1844674:c=18020000,e=59603730,p=199262,cr=199331,cu=0,mis=0,r=0,dep=0,og=1,plh=3298327531,tim=7861

… STAT #1844674 id=3 cnt=0 pid=2 pos=1 obj=0 op='SORT UNIQUE (cr=199331 pr=199262 pw=0

time=59603707 us cost=56817 size=126622640 card=2146146)' STAT #1844674 id=4 cnt=0 pid=3 pos=1 obj=0 op='UNION-ALL (cr=199331 pr=199262 pw=0 time=59603638 us)'

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Raw trace file Content of a sql trace file:

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tkprof (1)

SELECT RECID, TABLENAME, PROJECT_NUMBER, PROJECT_NAME, CARRYING_OUT_ORGANIZATION, COMPANY,

CHARGEABLE_FLAG, START_DATE, END_DATE, CREATION_DATE, LAST_UPDATE_DATE, PROCESSED_FLAG,

………………………………. …………………………….. WHERE PROCESSED_FLAG='U' ) ORDER BY TABLENAME, CREATION_DATE

call count cpu elapsed disk query current rows

------- ------ -------- ---------- ---------- ---------- ---------- ---------- Parse 1 0.01 0.01 0 0 0 0 Execute 1 0.00 0.00 0 0 0 0

Fetch 1 18.02 59.60 199262 199331 0 0 ------- ------ -------- ---------- ---------- ---------- ---------- ----------

total 3 18.03 59.61 199262 199331 0 0

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tkprof (2)

Rows (max) Row Source Operation ---------- --------------------------------------------------- 0 SORT ORDER BY (cr=199331 pr=199262 pw=0 time=59603767 us cost=180933 size=641697654 card=2146146) 0 VIEW (cr=199331 pr=199262 pw=0 time=59603722 us cost=56817 size=641697654 card=2146146) 0 SORT UNIQUE (cr=199331 pr=199262 pw=0 time=59603707 us cost=56817 size=126622640 card=2146146) 0 UNION-ALL (cr=199331 pr=199262 pw=0 time=59603638 us) 0 TABLE ACCESS FULL ORD_AP_IF_PROJECTS (cr=46025 pr=45963 pw=0 time=17088312 us cost=6568 size=85 card=1) 0 TABLE ACCESS FULL ORD_AP_IF_TASKS (cr=153306 pr=153299 pw=0 time=42515291 us cost=21894 size=126622555

Elapsed times include waiting on following events: Event waited on Times Max. Wait Total Waited ---------------------------------------- Waited ---------- ------------ SQL*Net message to client 1 0.00 0.00 Disk file operations I/O 129 0.01 0.26

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Usage   Displays execution plan stored in three different places

1) PLAN_TABLE dbms_xplan.diplay (estimated plan)

2) SGA of instance dbms_xplan.display_cursor (real plan from memory)

3) AWR dbms_xplan.display_awr (real,history plan from AWR)

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Comparison

Sl Tkprof Dbms_xplan 1 Trace must be enabled. Basic statistics are available in

memory and AWR 2 CBO notes are not visible Note section is very useful 3 No predicate Predicates printed from memory. 4 Bind values can be retrieved with

ease 5 Plan history can be retrieved

easily.

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dbms_xplan format arguments

Class level alias bytes cost note predicate parallel partition projection outlines peeked_binds remote rows

BASIC null X X X X X

TYPICAL X X X X X X X X

SERIAL X X X X X X

ALL X X X X X X X X X X X

ADVANCED X X X X X X X X X X X X

Format select * from table(dbms_xplan.display_cursor(‘sql_id’,child_number,’format’));

Examples: select * from table( dbms_xplan.display_cursor()); select * from table ( dbms_xplan.display_cursor (null,null, 'ADVANCED'));

select * from table ( dbms_xplan.display_cursor ('811a0zb26fw0x',0, 'BASIC')); select * from table ( dbms_xplan.display_cursor ('811a0zb26fw0x',0, ‘ALL -projection')); select * from table ( dbms_xplan.display_cursor ('811a0zb26fw0x',0, ‘ALL +peeked_binds'));

Format arguments: ' ADVANCED' ' –PREDICATE' ' –PREDICATE +OUTLINE'

Format arguments combinaKon: TYPICAL is the default class

SQL_ID 9sup9gfhhg32t, child number 0 ------------------------------------- SELECT RECID, TABLENAME, PROJECT_NUMBER, PROJECT_NAME, ……………………………………………………………………………………………L EDIT_CLASS_CODE, ALC, FRC FROM CCW_PA_IF_TASKS WHERE PROCESSED_FLAG='U' ) ORDER BY TABLENAME, CREATION_DATE

Plan hash value: 3298327531 --------------------------------------------------------------------------------------------------- | Id | Operation | Name | Rows | Bytes |TempSpc| Cost (%CPU)| Time | ---------------------------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | | | | 180K(100)| | | 1 | SORT ORDER BY | | 2146K| 611M| 698M| 180K (5)| 00:09:03 | | 2 | VIEW | | 2146K| 611M| | 56817 (10)| 00:02:51 | | 3 | SORT UNIQUE | | 2146K| 120M| 172M| 56817 (91)| 00:02:51 | | 4 | UNION-ALL | | | | | | | |* 5 | TABLE ACCESS FULL| ORD_AP_IF_PROJECTS | 1 | 85 | | 6568 (14)| 00:00:20 | |* 6 | TABLE ACCESS FULL| ORD_AP_IF_TASKS | 2146K| 120M| | 21894 (14)| 00:01:06 | ---------------------------------------------------------------------------------------------------- Predicate Information (identified by operation id): ---------------------------------------------------

5 - filter("PROCESSED_FLAG"='U') 6 - filter("PROCESSED_FLAG"='U')

Note ----- - SQL profile not used for this statement

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dbms_xplan.display

Optimizer estimates

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Display_cursor

select * from table(dbms_xplan.display_cursor('9yx90c0nwv9tk',0,'allstats'));

SQL_ID 9yx90c0nwv9tk, child number 0 ------------------------------------- SELECT /* gather_plan_statistics */ RECID, TABLENAME, ...

Plan hash value: 3298327531 --------------------------------------------------------------------------------------------------------------- | Id | Operation | Name | Starts | E-Rows | A-Rows | A-Time | Buffers | Reads | --------------------------------------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 1 | | 0 |00:00:32.50 | 199K| 199K| | 1 | SORT ORDER BY | | 1 | 2146K| 0 |00:00:32.50 | 199K| 199K| | 2 | VIEW | | 1 | 2146K| 0 |00:00:32.50 | 199K| 199K| | 3 | SORT UNIQUE | | 1 | 2146K| 0 |00:00:32.50 | 199K| 199K| | 4 | UNION-ALL | | 1 | | 0 |00:00:32.50 | 199K| 199K| |* 5 | TABLE ACCESS FULL| ORD_AP_IF_PROJECTS | 1 | 1 | 0 |00:00:07.90 | 46025 | 45963 | |* 6 | TABLE ACCESS FULL| ORD_AP_IF_TASKS | 1 | 2146K| 0 |00:00:24.60 | 153K| 153K| ---------------------------------------------------------------------------------------------------------------

Predicate Information (identified by operation id): --------------------------------------------------- 5 - filter("PROCESSED_FLAG"='U') 6 - filter("PROCESSED_FLAG"='U')

Note, output formatted to fit screen

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Easily quantify the solution given..

select * from table(dbms_xplan.display_cursor('9yx90c0nwv9tk',0,'allstats'));

Plan hash value: 932773089

---------------------------------------------------------------------------------------------------------------------------------------------- | Id | Operation | Name | Starts | E-Rows | A-Rows | A-Time | Buffers | OMem | 1Mem | Used-Mem | ---------------------------------------------------------------------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 1 | | 0 |00:00:00.01 | 6 | | | | | 1 | SORT ORDER BY | | 1 | 2146K| 0 |00:00:00.01 | 6 | 1024 | 1024 | | | 2 | VIEW | | 1 | 2146K| 0 |00:00:00.01 | 6 | | | | | 3 | SORT UNIQUE | | 1 | 2146K| 0 |00:00:00.01 | 6 | 1024 | 1024 | | | 4 | UNION-ALL | | 1 | | 0 |00:00:00.01 | 6 | | | | | 5 | TABLE ACCESS BY INDEX ROWID| ORD_PA_IF_PROJECTS | 1 | 1 | 0 |00:00:00.01 | 3 | | | | |* 6 | INDEX RANGE SCAN | ORD_PA_IF_PROJECTS_N1 | 1 | 1 | 0 |00:00:00.01 | 3 | | | | | 7 | TABLE ACCESS BY INDEX ROWID| ORD_PA_IF_TASKS | 1 | 2146K| 0 |00:00:00.01 | 3 | | | | |* 8 | INDEX RANGE SCAN | ORD_PA_IF_TASKS_N1 | 1 | 2173K| 0 |00:00:00.01 | 3 | | | | ----------------------------------------------------------------------------------------------------------------------------------------------

Predicate Information (identified by operation id): ---------------------------------------------------

6 - access("PROCESSED_FLAG"='U') 8 - access("PROCESSED_FLAG"='U')

Note -----

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Privileges

For dbms_xplan.display_awr grant select on dba_hist_sqltext to scott grant select on dba_hist_sql_plan to scott; grant select on v_$database to scott; OR SELECT_CATALOG role

  Privileges needed to execute dbms_xplan

For dbms_xplan.display_cursor grant select on v_$session to scott; grant select on v_$SQL_PLAN_STATISTICS_ALL to scott; grant select on v_$sql to scott; grant select on v_$sql_plan to scott; OR SELECT_CATALOG role or select any dictionary system privilege

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Internals of dbms_xplan

select * from (table(dbms_xplan.display_cursor('8gzkcsvw362s3',2,'allstats'));

select /* EXEC_FROM_DBMS_XPLAN */ case when upper(sql_text) like '%DBMS_XPLAN%' then 0 else 1 end case, SQL_ID, child_number from v$sql where SQL_ID ='8gzkcsvw362s3' and child_number =2

SELECT /*+ opt_param('parallel_execution_enabled', 'false') */ extractvalue(xmlval, '/*/info[@type = "sql_profile"]'), extractvalue(xmlval, '/*/info[@type = "sql_patch"]'), extractvalue(xmlval, '/*/info[@type = "baseline"]'), extractvalue(xmlval, '/*/info[@type = "outline"]'), extractvalue(xmlval, '/*/info[@type = "dynamic_sampling"]'), extractvalue(xmlval, '/*/info[@type = "dop"]'), extractvalue(xmlval, '/*/info[@type = "dop_reason"]'), extractvalue(xmlval, '/*/info[@type = "queuing_reason"]'), extractvalue(xmlval, '/*/info[@type = "row_shipping"]') , extractvalue(xmlval, '/*/info[@type = "index_size"]'), extractvalue(xmlval, '/*/info[@type = "result_checksum"]'), extractvalue(xmlval, '/*/info[@type = "cardinality_feedback"]'), extractvalue(xmlval, '/*/info[@type = "xml_suboptimal"]'), extractvalue(xmlval,'/*/info[@type = "plan_hash"]') from (select xmltype(:v_other_xml) xmlval from dual)

SELECT PLAN_TABLE_OUTPUT FROM TABLE(CAST(DBMS_XPLAN.PREPARE_RECORDS(:B1 , :B2 ) AS SYS.DBMS_XPLAN_TYPE_TABLE))

Really complicated recursive SQL statements!

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More internals

SELECT /*+ opt_param('parallel_execution_enabled', 'false') */ /* EXEC_FROM_DBMS_XPLAN */ id, position, depth , operation, options, object_name, cardinality, bytes, temp_space, cost, io_cost, cpu_cost, time, ….

vp.optimal_executions opt_cnt, vp.onepass_executions one_cnt, vp.multipasses_executions multi_cnt, vp.max_tempseg_size max_tmp, vp.last_tempseg_size last_tmp from V$SQL_PLAN_STATISTICS_ALL vp, v$sql where vp.SQL_ID = '8gzkcsvw362s3' and vp.child_number=2 and vp.SQL_ID = v$sql.SQL_ID and v$sql.child_number=2) order by id

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How do I tune?

my_sql.sql Set linesize 300; set pagesize 1000; --Declare variable and assign values var order_id number; execute :order_id:=53759119 SELECT oeh.header_id, oel.line_id FROM oe_order_headers_all oeh, oe_order_lines_all oel WHERE oeh.header_id = :order_id AND oeh.header_id = oel.header_id / select * from table (dbms_xplan.DISPLAY_CURSOR(null, null, 'ALLSTATS')) /

  Prepare the sql to be run for performance analysis.

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Do’s & Don’ts   Do’s

1.  Current execution plan and runtime statistics are the first step.

2.  Execute a test case first to reproduce.

  Don’t

1.  Try to use same bind type as application uses.

- Literal vs bind variables - number vs varchar2 data type etc

2.  Try to use format same as the application for your test case.

- CTAS vs INSERT

PLAN_TABLE_OUTPUT SQL_ID cttafpfjwqjdm, child number 0 ------------------------------------- select oeh.header_id,oel.line_id from oe_order_headers_all oeh,oe_order_lines_all oel where oeh.header_id=:order_id and oeh.header_id=oel.header_id


--------------------------------------------------------------------------------------------------------------------------- | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | Pstart| Pstop | --------------------------------------------------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | | | 11 (100)| | | | | 1 | NESTED LOOPS | | 6 | 114 | 11 (0)| 00:00:01 | | | | 2 | PARTITION HASH SINGLE | | 1 | 6 | 2 (0)| 00:00:01 | KEY | KEY | |* 3 | INDEX UNIQUE SCAN | OE_ORDER_HEADERS_U1 | 1 | 6 | 2 (0)| 00:00:01 | KEY | KEY | | 4 | TABLE ACCESS BY GLOBAL INDEX ROWID| OE_ORDER_LINES_ALL | 6 | 78 | 9 (0)| 00:00:01 | ROWID | ROWID | |* 5 | INDEX RANGE SCAN | OE_ORDER_LINES_N1 | 6 | | 3 (0)| 00:00:01 | | | ---------------------------------------------------------------------------------------------------------------------------

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dbms_xplan.display_cursor

...


3 - access("OEH"."HEADER_ID"=:ORDER_ID) 5 - access("OEL"."HEADER_ID"=:ORDER_ID)

Note -----

- Warning These are only collected when: * hint 'gather_plan_statistics' is used for the statement or

* parameter 'statistics_level' is set to 'ALL', at session or system level * Cardinality feedback used * Dynamic sampling used

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dbms_xplan.display_cursor ..2

-------------------------------------------------------------------------------------------------------------------------- | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | Pstart| Pstop | --------------------------------------------------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | | | 11200 (100)| | | | | 1 | NESTED LOOPS | | 6 | 114 | 11 (0)| 00:10:01 | | | | 2 | PARTITION HASH SINGLE | | 1 | 6 | 2 (0)| 00:00:01 | KEY | KEY | |* 3 | INDEX UNIQUE SCAN | OE_ORDER_HEADERS_U1 | 1 | 6 | 2 (0)| 00:00:01 | KEY | KEY | |* 4 | TABLE ACCESS BY GLOBAL INDEX ROWID| OE_ORDER_LINES_ALL | 6 | 78 | 9000 (0)| 00:07:01 | ROWID | ROWID | |* 5 | INDEX RANGE SCAN | OE_ORDER_LINES_N1 | 60000 | | 300 (0)| 00:03:01 | | | ---------------------------------------------------------------------------------------------------------------------------

Predicate Information (identified by operation id): --------------------------------------------------- 3 - access("OEH"."HEADER_ID"=:ORDER_ID) 4 – filter ("OEL".“OPEN_FLAG=’Y’) 5 - access("OEL"."HEADER_ID"=:ORDER_ID)

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dbms_xplan: access and filter predicates

Added a predicate oel.open_flag=‘Y’

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Detailed execution statistics   v$sql_plan_statistics_all collects row source level execution

statistics   ROWS

  CPU

  Physical IO

  Logical IO

  Elapsed time

  To enable at session level set statistics_level=‘ALL’

  To enable for all sessions set at system level statistics_level=‘ALL’

  To set a SQL statement level add the hint

  /*+ gather_plan_statistics */ in the statement.

Setting statistics_level=‘ALL’ at system level can be resource intensive and should preferably not be enabled in busy PRODUCTION SYSTEM

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dbms_xplan: script

--my_sql.sql script_name set linesize 300; set pagesize 1000; --Declare variable and assign values var order_id number; execute order_id:=53759119 alter session set statistics_level=‘ALL’; --OR ADD HINT SELECT /*+ gather_plan_statistics */ oeh.header_id, oel.line_id FROM oe_order_headers_all oeh, oe_order_lines_all oel WHERE oeh.header_id = :order_id AND oeh.header_id = oel.header_id /

  Modify the script to enable extended execution statistics

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Execution statistics

SQL_ID 7gftgf917tg2x, child number 0 ------------------------------------- select /*+ gather_plan_statistics */ oeh.header_id,oel.line_id from oe_order_headers_all oeh,oe_order_lines_all oel where oeh.header_id=:order_id and oeh.header_id=oel.header_id


------------------------------------------------------------------------------------------------------------------------------ | Id | Operation | Name | Starts | E-Rows | A-Rows | A-Time | Buffers | Reads | ------------------------------------------------------------------------------------------------------------------------------ | 0 | SELECT STATEMENT | | 1 | | 4 |00:00:00.03 | 12 | 11 | | 1 | NESTED LOOPS | | 1 | 6 | 4 |00:00:00.03 | 12 | 11 | | 2 | PARTITION HASH SINGLE | | 1 | 1 | 1 |00:00:00.01 | 3 | 3 | |* 3 | INDEX UNIQUE SCAN | OE_ORDER_HEADERS_U1 | 1 | 1 | 1 |00:00:00.01 | 3 | 3 | | 4 | TABLE ACCESS BY GLOBAL INDEX ROWID| OE_ORDER_LINES_ALL | 1 | 6 | 4 |00:00:00.02 | 9 | 8 | |* 5 | INDEX RANGE SCAN | OE_ORDER_LINES_N1 | 1 | 6 | 4 |00:00:00.01 | 5 | 4 | ------------------------------------------------------------------------------------------------------------------------------


3 - access("OEH"."HEADER_ID"=:ORDER_ID) 5 - access("OEL"."HEADER_ID"=:ORDER_ID)

25 rows selected.

select * from table (dbms_xplan.DISPLAY_CURSOR(null, null, 'ALLSTATS LAST')) /

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Alias

select * from table (dbms_xplan.DISPLAY_CURSOR(null, null, 'ALLSTATS LAST +alias -predicate'));

SELECT /*+ gather_plan_statistics */ oel.line_id FROM oe_order_lines_all oel WHERE oel.open_flag = 'Y' and exists (select 1 from oe_order_headers_all oeh where oeh.header_id = oel.header_id and oeh.open_flag='Y' and oeh.last_update_date > sysdate -5)

Plan hash value: 746840967 -------------------------------------------------------------------------------------------------------------------------------------------------------- | Id | Operation | Name | Starts | E-Rows | A-Rows | A-Time | Buffers | OMem | 1Mem | Used-Mem |

-------------------------------------------------------------------------------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 1 | | 3 |00:00:00.01 | 16 | | | |

| 1 | NESTED LOOPS | | 1 | | 3 |00:00:00.01 | 16 | | | | | 2 | NESTED LOOPS | | 1 | 1 | 3 |00:00:00.01 | 10 | | | | | 3 | SORT UNIQUE | | 1 | 1 | 1 |00:00:00.01 | 5 | 2048 | 2048 | 2048 (0)|

| 4 | TABLE ACCESS BY GLOBAL INDEX ROWID| OE_ORDER_HEADERS_ALL | 1 | 1 | 1 |00:00:00.01 | 5 | | | | | 5 | INDEX RANGE SCAN | CCW_OE_ORD_HEADERS_ALL_D1 | 1 | 7 | 1 |00:00:00.01 | 4 | | | |

| 6 | INDEX RANGE SCAN | OE_ORDER_LINES_N1 | 1 | 6 | 3 |00:00:00.01 | 5 | | | | | 7 | TABLE ACCESS BY GLOBAL INDEX ROWID | OE_ORDER_LINES_ALL | 3 | 1 | 3 |00:00:00.01 | 6 | | | | --------------------------------------------------------------------------------------------------------------------------------------------------------

Query Block Name / Object Alias (identified by operation id): ------------------------------------------------------------- 1 - SEL$5DA710D3 4 - SEL$5DA710D3 / OEH@SEL$2 5 - SEL$5DA710D3 / OEH@SEL$2 6 - SEL$5DA710D3 / OEL@SEL$1 7 - SEL$5DA710D3 / OEL@SEL$1

SQL_ID cu2f3xhzy75vc, child number 0 ------------------------------------- SELECT /*+ gather_plan_statistics qb_name(outer_block) */ oel.line_id FROM oe_order_lines_all oel WHERE oel.open_flag = 'Y' and exists (select /*+ qb_name(innner_block) */ 1 from oe_order_headers_all oeh where oeh.header_id = oel.header_id and oeh.open_flag='Y' and oeh.last_update_date > sysdate -5);

Plan hash value: 746840967 -------------------------------------------------------------------------------------------------------------------- | Id | Operation | Name | Starts | E-Rows | A-Rows | A-Time | ..| --------------------------------------------------------------------------------------------------------------------.. | 0 | SELECT STATEMENT | | 1 | | 3 |00:00:00.01 |

…

Query Block Name / Object Alias (identified by operation id): ------------------------------------------------------------- 1 - SEL$8E94A21F 4 - SEL$8E94A21F / OEH@INNNER_BLOCK 5 - SEL$8E94A21F / OEH@INNNER_BLOCK 6 - SEL$8E94A21F / OEL@OUTER_BLOCK 7 - SEL$8E94A21F / OEL@OUTER_BLOCK

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Query Block name

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Default QB Name

Prefix Row Source operation

CRI$ Create index statement

DEL$ DELETE statement INS$ Insert Statement

MISC$ Miesc SQL like lock table

MRG$ Merge Statement

SEL$ SELECT statement

SET$ Set operators

UPD$ Update statement

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Hints or Outlines

set linesize 300 set pagesize 300 alter session set statistics_level='ALL';

SELECT /* outline query */ RECID, ALC, FRC ... FROM ORD_AP_IF_TASK WHERE PROCESSED_FLAG = 'U') ORDER BY TABLENAME, CREATION_DATE;

select * from table( dbms_xplan.display_cursor

(null,null,'ALLSTATS LAST +outline')) /

Outline Data ------------- /*+ BEGIN_OUTLINE_DATA IGNORE_OPTIM_EMBEDDED_HINTS OPTIMIZER_FEATURES_ENABLE('11.2.0.2') OPT_PARAM('_b_tree_bitmap_plans' 'false') OPT_PARAM('_fast_full_scan_enabled' 'false') ALL_ROWS OUTLINE_LEAF(@"SEL$2") OUTLINE_LEAF(@"SEL$1") FULL(@"SEL$3" "ORD_AP_IF_TASKS"@"SEL$3") INDEX_RS_ASC(@"SEL$2" "ORD_AP_IF_PROJECTS"@"SEL$2“

("ORD_AP_IF_PROJECTS"."PROCESSED_FLAG")) END_OUTLINE_DATA */

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Outline --------------------------------------------------------------------------------------------------------------------- | Id | Operation | Name | Starts | E-Rows | A-Rows | A-Time | Buffers | … -------------------------------------------------------------------------------------------------------------------… | 0 | SELECT STATEMENT | | 1 | | 0 |00:00:27.40 | 153K| .. | 1 | SORT ORDER BY | | 1 | 2146K| 0 |00:00:27.40 | 153K| … | 2 | VIEW | | 1 | 2146K| 0 |00:00:27.40 | 153K| … | 3 | SORT UNIQUE | | 1 | 2146K| 0 |00:00:27.40 | 153K| … | 4 | UNION-ALL | | 1 | | 0 |00:00:27.40 | 153K| … | 5 | TABLE ACCESS BY INDEX ROWID| ORD_AP_IF_PROJECTS | 1 | 1 | 0 |00:00:00.01 | 3 | … | 6 | INDEX RANGE SCAN | ORD_AP_IF_PROJECTS_N1 | 1 | 1 | 0 |00:00:00.01 | 3 | | 7 | TABLE ACCESS FULL | ORD_AP_IF_TASKS | 1 | 2146K| 0 |00:00:27.40 | 153K| -------------------------------------------------------------------------------------------------------------------


6 - access("PROCESSED_FLAG"='U') 7 - filter("PROCESSED_FLAG"='U')

Outline Data ------------- /*+ ... FULL(@"SEL$3" "ORD_AP_IF_TASKS"@"SEL$3") INDEX_RS_ASC(@"SEL$2" "ORD_AP_IF_PROJECTS "@"SEL$2" ("ORD_AP_IF_PROJECTS"."PROCESSED_FLAG")) END_OUTLINE_DATA */

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Tuning SQL

SQLPLUS> select count(1) from ORD_AP_IF_TASKS where PROCESSED_FLAG='U'; COUNT(1) ---------- 0

There is an index on ORD_AP_IF_TASKS.PROCESSED_FLAG

set linesize 300 set pagesize 300 alter session set statistics_level='ALL'; SELECT /*+ BEGIN_OUTLINE_DATA IGNORE_OPTIM_EMBEDDED_HINTS OPTIMIZER_FEATURES_ENABLE('11.2.0.2') DB_VERSION('11.2.0.2') OPT_PARAM('_b_tree_bitmap_plans' 'false') OPT_PARAM('_fast_full_scan_enabled' 'false') ALL_ROWS OUTLINE_LEAF(@"SEL$2") OUTLINE_LEAF(@"SEL$3") OUTLINE_LEAF(@"SET$1") OUTLINE_LEAF(@"SEL$1") NO_ACCESS(@"SEL$1" "from$_subquery$_001"@"SEL$1")

INDEX_RS_ASC(@"SEL$3" “ORD_AP_IF_TASKS"@"SEL$3" (“ORD_AP_IF_TASKS"."PROCESSED_FLAG")) INDEX_RS_ASC(@"SEL$2" “ORD_AP_IF_PROJECTS"@"SEL$2" (“ORD_AP_IF_PROJECTS"."PROCESSED_FLAG")) END_OUTLINE_DATA */ WHERE PROCESSED_FLAG = 'U') ORDER BY TABLENAME, CREATION_DATE /

select * from table(dbms_xplan.display_cursor

(null,null,'ALLSTATS LAST +outline')) /

30

Bob the Builder

FULL(@"SEL$3" "ORD_AP_IF_TASKS"@"SEL$3")

Copying outline as hint; Altering Full Table Scan

to Index Range Scan.

31

Tuned Plan ---------------------------------------------------------------------------------------------------------… | Id | Operation | Name | Starts | E-Rows | A-Rows | A-Time | --------------------------------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 1 | | 0 |00:00:00.01 | | 1 | SORT ORDER BY | | 1 | 2146K| 0 |00:00:00.01 | | 2 | VIEW | | 1 | 2146K| 0 |00:00:00.01 | | 3 | SORT UNIQUE | | 1 | 2146K| 0 |00:00:00.01 | | 4 | UNION-ALL | | 1 | | 0 |00:00:00.01 | | 5 | TABLE ACCESS BY INDEX ROWID| ORD_AP_IF_PROJECTS | 1 | 1 | 0 |00:00:00.01 | |* 6 | INDEX RANGE SCAN | ORD_AP_IF_PROJECTS_N1 | 1 | 1 | 0 |00:00:00.01 | | 7 | TABLE ACCESS BY INDEX ROWID| ORD_AP_IF_TASKS | 1 | 2146K| 0 |00:00:00.01 | |* 8 | INDEX RANGE SCAN | ORD_AP_IF_TASKS_N1 | 1 | 2173K| 0 |00:00:00.01 | ---------------------------------------------------------------------------------------------------------… Outline Data ------------- /*+ BEGIN_OUTLINE_DATA IGNORE_OPTIM_EMBEDDED_HINTS OPT_PARAM('_b_tree_bitmap_plans' 'false') OPT_PARAM('_fast_full_scan_enabled' 'false') ALL_ROWS OUTLINE_LEAF(@"SEL$1") NO_ACCESS(@"SEL$1" "from$_subquery$_001"@"SEL$1") INDEX_RS_ASC(@"SEL$3" “ORD_AP_IF_TASKS"@"SEL$3" (“ORD_A__IF_TASKS"."PROCESSED_FLAG")) INDEX_RS_ASC(@"SEL$2" “ORD_AP_IF_PROJECTS"@"SEL$2" (“ORD_AP_IF_PROJECTS"."PROCESSED_FLAG")) END_OUTLINE_DATA */ Predicate Information (identified by operation id): --------------------------------------------------- 6 - access("PROCESSED_FLAG"='U') 8 - access("PROCESSED_FLAG"='U’)

32

So many details..So little space.. Column Description Always available columns

id Identified of each step in the execution plan; if prefixed with * then predicate information available in predicate section

Operation Row source operation Name The database object in the operation CBO parse time information

Rows Estimated number of rows returned by the row source operation; derived from statistics on names object in the operation Bytes Estimated amount of data returned by the operation

TempSpc The estimated amount of temp space usage by the operation

Cost(%CPU) The estimated cost of the row source operation. The percentage CPU cost is given in () for individual row source operation Time Estimated amount of time needed to execute that operation in HH:MM:SS Partitioning Pstart Number of first partition to be accessed Pstop The number of last partition to be accessed Parallel Processing TQ Table queue used for processing IN-OUT The relation between parallel operations

PQ Distrib The distribution used by producers to send data to consumers Runtime Statistics Starts The number of times operation was executed (check more nested loop joins operation) A-Rows Actual number of rows returned A-Time Actual amount of time spent executing the operation I/O Statistics

Buffers Logical reads operations performed during execution of each step Read Physical reads performed for each operation Write Physical writes performed

33

dbms_xplan.display_awr

Format select * from table(dbms_xplan.display_awr(‘sql_id’,plan_hash_value,db_id,’format’));

-‐plan_hash_value: to select a specific plan

-‐dbid : specifies which database to select from

  Displays plans stored in AWR;

Example script: SELECT * FROM TABLE( dbms_xplan.display_awr('&&sql_id', '&plan_hash_value',

NULL, 'ALL +peeked_binds') );

34

dbms_xplan.display_awr

SQL_ID 4jtbgawt37mcd -------------------- Plan hash value: 327243540

--------------------------------------------------------------------------------------------------------------- | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | ---------------------------------------------------------------------------------------------------------------

Peeked Binds (identified by position): --------------------------------------

1 - :B3 (NUMBER): 7394 2 - :B2 (VARCHAR2(30), CSID=871): 'AAL' 3 - :B1 (VARCHAR2(30), CSID=871): '73057'

SQL_ID 4jtbgawt37mcd -------------------- Plan hash value: 2294473928 --------------------------------------------------------------------------------------------------------------- | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | ---------------------------------------------------------------------------------------------------------------

Peeked Binds (identified by position): -------------------------------------- 1 - :B3 (NUMBER): 9649 2 - :B2 (VARCHAR2(30), CSID=871): 'ZXU' 3 - :B1 (VARCHAR2(30), CSID=871): 'U5152'

select * from table(dbms_xplan.display_awr('4jtbgawt37mcd',null, null, 'ALL +peeked_binds'));

©OraInternals Riyaj Shamsudeen 35

Cardinality feedback

Demo @demo_oh1.sql

select /*+ gather_plan_statistics */ max(length(v1)) from order_headers_all where processed_flag='N'


--------------------------------------------------------------------------- | Id | Operation | Name | Starts | E-Rows | A-Rows |

--------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 1 | | 1 |

| 1 | SORT AGGREGATE | | 1 | 1 | 1 | |* 2 | TABLE ACCESS FULL| ORDER_HEADERS_ALL | 1 | 50000 | 10 | ---------------------------------------------------------------------------

Predicate Information (identified by operation id):

---------------------------------------------------

2 - filter("PROCESSED_FLAG"='N')


Starts

Demo @demo_oh2.sql

SELECT /*+ no_rewrite gather_plan_statistics */ MAX(LENGTH(oh.v1)), MAX(LENGTH(oh.v1)) FROM order_headers_all oh WHERE EXISTS ( SELECT 1 FROM order_lines_all ol WHERE oh.order_id = ol.order_id AND line_processed_flag = 'Y' AND rownum >=1 ) AND oh.processed_flag='N' ;

How many times did the EXISTS Subquery was executed?


ALLSTATS LAST

Demo @demo_oh2.sql

---------------------------------------------------------------------------------------- | Id | Operation | Name | Starts | E-Rows | A-Rows | ----------------------------------------------------------------------------------------

| 0 | SELECT STATEMENT | | 1 | | 1 | | 1 | SORT AGGREGATE | | 1 | 1 | 1 | |* 2 | FILTER | | 1 | | 10 | |* 3 | TABLE ACCESS FULL | ORDER_HEADERS_ALL | 1 | 50000 | 10 | | 4 | COUNT | | 10 | | 10 |

|* 5 | FILTER | | 10 | | 10 | |* 6 | TABLE ACCESS BY INDEX ROWID| ORDER_LINES_ALL | 10 | 1 | 10 | |* 7 | INDEX RANGE SCAN | OL_N1 | 10 | 1 | 10 | ----------------------------------------------------------------------------------------


2 - filter( IS NOT NULL) 3 - filter("OH"."PROCESSED_FLAG"='N')

5 - filter(ROWNUM>=1) 6 - filter("LINE_PROCESSED_FLAG"='Y') 7 - access("OL"."ORDER_ID"=:B1)

select * from table (dbms_xplan.display_cursor ('', '','ALLSTATS LAST'))


Starts ..2

SELECT 1 FROM PA_TASKS WHERE TASK_ID = :B1


-------------------------------------------------------------------- | Id | Operation | Name | Starts | E-Rows | A-Rows | -------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 256K| | 246K| |* 1 | INDEX UNIQUE SCAN| PA_TASKS_U1 | 256K| 1 | 246K| --------------------------------------------------------------------


1 - access("TASK_ID"=:B1)

select * from table (dbms_xplan.display_cursor ('', '','ALLSTATS'))

How many times did we execute this statement?


Cardinality feedback ..2

------------------------------------------------------------------------------------------

| Id | Operation | Name | Starts | E-Rows | A-Rows | ------------------------------------------------------------------------------------------

| 0 | UPDATE STATEMENT | | 7822 | | 0 | | 1 | UPDATE | ENI_OLTP_ITEM_STAR | 7822 | | 0 | |* 2 | FILTER | | 7824 | | 7254K|

|* 3 | TABLE ACCESS BY ROWID RANGE| ENI_OLTP_ITEM_STAR | 7823 | 69121 | 7256K| | 4 | TABLE ACCESS BY INDEX ROWID | MTL_SYSTEM_ITEMS_B | 7171K| 1 | 7167K|

|* 5 | INDEX UNIQUE SCAN | MTL_SYSTEM_ITEMS_B_U1 | 7176K| 1 | 7172K| ------------------------------------------------------------------------------------------



Cardinality feedback ..3

------------------------------------------------------------------------------------------------------- | Id | Operation | Name | Starts | A-Time | Buffers | Reads | ------------------------------------------------------------------------------------------------------- | 0 | UPDATE STATEMENT | | 7822 |00:47:24.86 | 56M| 1082K| | 1 | UPDATE | ENI_OLTP_ITEM_STAR | 7822 |00:47:24.86 | 56M| 1082K| |* 2 | FILTER | | 7824 |00:01:27.46 | 23M| 868 | |* 3 | TABLE ACCESS BY ROWID RANGE| ENI_OLTP_ITEM_STAR | 7823 |00:01:23.30 | 23M| 868 | | 4 | TABLE ACCESS BY INDEX ROWID | MTL_SYSTEM_ITEMS_B | 7171K|00:41:09.13 | 25M| 1028K| |* 5 | INDEX UNIQUE SCAN | MTL_SYSTEM_ITEMS_B_U1 | 7176K|00:01:17.74 | 17M| 488 | -------------------------------------------------------------------------------------------------------


2 - filter(CHARTOROWID(:B2)<=CHARTOROWID(:B1)) 3 - access(ROWID>=CHARTOROWID(:B2) AND ROWID<=CHARTOROWID(:B1)) 5 - access("MTI"."INVENTORY_ITEM_ID"=:B1 AND "MTI"."ORGANIZATION_ID"=:B2)



SQL - remote

Demo @demo_oh3.sql

WITH rem1 AS (SELECT /*+ materialize */ order_id FROM oli_table@orcl2 ol WHERE line_processed_flag='Y' ) SELECT /*+ no_rewrite gather_plan_statistics */ MAX(LENGTH(oh.v1)) FROM order_headers_all oh WHERE EXISTS (SELECT 1 FROM rem1 WHERE oh.order_id = rem1.order_id ) AND oh.processed_flag='N' ;


Remote queries

Demo @demo_oh3.sql

--------------------------------------------------------------------------------------------- | Id | Operation | Name | Starts | E-Rows | A-Rows | --------------------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 1 | | 1 | | 1 | TEMP TABLE TRANSFORMATION | | 1 | | 1 | | 2 | LOAD AS SELECT | | 1 | | 0 | | 3 | REMOTE | OLI_TABLE | 1 | 100K| 100K| | 4 | SORT AGGREGATE | | 1 | 1 | 1 | |* 5 | HASH JOIN RIGHT SEMI | | 1 | 50000 | 10 | | 6 | VIEW | | 1 | 100K| 100K| | 7 | TABLE ACCESS FULL | SYS_TEMP_0FD9FC884_E8A367F2 | 1 | 100K| 100K| |* 8 | TABLE ACCESS FULL | ORDER_HEADERS_ALL | 1 | 50000 | 10 | ---------------------------------------------------------------------------------------------


5 - access("OH"."ORDER_ID"="REM1"."ORDER_ID") 8 - filter("OH"."PROCESSED_FLAG"='N')

… Remote SQL Information (identified by operation id): ----------------------------------------------------

3 - SELECT /*+ */ "ORDER_ID","LINE_PROCESSED_FLAG" FROM "OLI_TABLE" "OL" WHERE LINE_PROCESSED_FLAG"='Y' (accessing ‘ORCL2.ORACLE.com' )

ADVANCED option provides remote query output


SQL – remote ..2

Demo @demo_oh3.sql

SELECT /*+ no_rewrite gather_plan_statistics use_nl (oh ol) */ MAX(LENGTH(oh.v1)) FROM order_headers_all oh, (SELECT order_id FROM oli_table@orcl2 ol WHERE line_processed_flag='Y' ) ol WHERE oh.order_id = ol.order_id AND oh.processed_flag='N' ;


Remote queries (2)

Demo @demo_oh5.sql

------------------------------------------------------------------------------------ | Id | Operation | Name | Rows | Bytes | Cost (%CPU)|IN-OUT| ------------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | | | 100K(100)| | | 1 | SORT AGGREGATE | | 1 | 223 | | | | 2 | NESTED LOOPS | | 50000 | 10M| 100K (1)| | |* 3 | TABLE ACCESS FULL| ORDER_HEADERS_ALL | 50000 | 9M| 403 (7)| | | 4 | REMOTE | OLI_TABLE | 1 | 15 | 2 (0)| R->S | -------------------------------------------------------------------------------------

Predicate Information (identified by operation id): --------------------------------------------------- 3 - filter("OH"."PROCESSED_FLAG"='N')

Remote SQL Information (identified by operation id): ----------------------------------------------------

4 - SELECT /*+ USE_NL ("OL") */ "ORDER_ID", "LINE_PROCESSED_FLAG" FROM "OLI_TABLE" "OL" WHERE "LINE_PROCESSED_FLAG"='Y' AND :1="ORDER_ID“ (accessing ‘ORCL2.ORCL.COM' )


Parallel Queries ---------------------------------------------------------------------------------------------------- | Id | Operation | Name | Starts | E-Rows | A-Rows | A-Time | ---------------------------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 1 | | 1 |00:00:08.83 | | 1 | SORT AGGREGATE | | 1 | 1 | 1 |00:00:08.83 | |* 2 | HASH JOIN | | 1 | 999K| 260K|00:00:08.76 | | 3 | VIEW | | 1 | 999K| 999K|00:00:02.11 | |* 4 | COUNT STOPKEY | | 1 | | 999K|00:00:01.52 | | 5 | PX COORDINATOR | | 1 | | 999K|00:00:00.84 | | 6 | PX SEND QC (RANDOM) | :TQ10000 | 0 | 11M| 0 |00:00:00.01 | |* 7 | COUNT STOPKEY | | 0 | | 0 |00:00:00.01 | | 8 | PX PARTITION HASH ALL| | 0 | 11M| 0 |00:00:00.01 | | 9 | INDEX FULL SCAN | OE_ORDER_HEADERS_U1 | 0 | 11M| 0 |00:00:00.01 | | 10 | VIEW | | 1 | 999K| 999K|00:00:02.28 | |* 11 | COUNT STOPKEY | | 1 | | 999K|00:00:01.68 | | 12 | INDEX FULL SCAN | OE_ORDER_LINES_N1 | 1 | 57M| 999K|00:00:00.98 | ----------------------------------------------------------------------------------------------------


2 - access("OH"."HEADER_ID"="OL"."HEADER_ID") 4 - filter(ROWNUM<1000000) 7 - filter(ROWNUM<1000000) 11 - filter(ROWNUM<1000000)

Note -----

- Degree of Parallelism is 8 because of hint

ALLSTATS LAST

Also, notice the broken cardinality Feedback.


Parallel Queries --------------------------------------------------------------------------------------------------- | Id | Operation | Name | Starts | E-Rows | A-Rows | A-Time | ---------------------------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 1 | | 1 |00:00:08.83 | | 1 | SORT AGGREGATE | | 1 | 1 | 1 |00:00:08.83 | |* 2 | HASH JOIN | | 1 | 999K| 260K|00:00:08.76 | | 3 | VIEW | | 1 | 999K| 999K|00:00:02.11 | |* 4 | COUNT STOPKEY | | 1 | | 999K|00:00:01.52 | | 5 | PX COORDINATOR | | 1 | | 999K|00:00:00.84 | | 6 | PX SEND QC (RANDOM) | :TQ10000 | 0 | 11M| 0 |00:00:00.01 | |* 7 | COUNT STOPKEY | | 8 | | 1072K|00:00:03.83 | | 8 | PX PARTITION HASH ALL| | 8 | 11M| 1072K|00:00:03.17 | | 9 | INDEX FULL SCAN | OE_ORDER_HEADERS_U1 | 8 | 11M| 1072K|00:00:02.56 | | 10 | VIEW | | 1 | 999K| 999K|00:00:02.28 | |* 11 | COUNT STOPKEY | | 1 | | 999K|00:00:01.68 | | 12 | INDEX FULL SCAN | OE_ORDER_LINES_N1 | 1 | 57M| 999K|00:00:00.98 | ----------------------------------------------------------------------------------------------------


2 - access("OH"."HEADER_ID"="OL"."HEADER_ID") 4 - filter(ROWNUM<1000000) 7 - filter(ROWNUM<1000000) 11 - filter(ROWNUM<1000000)

Note -----


ALLSTATS

After 1 execution with DOP=8


Parallel Queries

---------------------------------------------------------------------------------------------------- | Id | Operation | Name | Starts | E-Rows | A-Rows | A-Time | ---------------------------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 4 | | 4 |00:00:38.25 | | 1 | SORT AGGREGATE | | 4 | 1 | 4 |00:00:38.25 | |* 2 | HASH JOIN | | 4 | 999K| 418K|00:00:38.16 | | 3 | VIEW | | 4 | 999K| 3999K|00:00:07.67 | |* 4 | COUNT STOPKEY | | 4 | | 3999K|00:00:05.53 | | 5 | PX COORDINATOR | | 4 | | 3999K|00:00:03.12 | | 6 | PX SEND QC (RANDOM) | :TQ10000 | 0 | 11M| 0 |00:00:00.01 | |* 7 | COUNT STOPKEY | | 64 | | 4779K|00:00:56.27 | | 8 | PX PARTITION HASH ALL| | 64 | 11M| 4779K|00:00:53.19 | | 9 | INDEX FULL SCAN | OE_ORDER_HEADERS_U1 | 64 | 11M| 4779K|00:00:50.33 | | 10 | VIEW | | 4 | 999K| 3999K|00:00:14.59 | |* 11 | COUNT STOPKEY | | 4 | | 3999K|00:00:12.32 | | 12 | PX COORDINATOR | | 4 | | 3999K|00:00:09.35 | | 13 | PX SEND QC (RANDOM) | :TQ20000 | 0 | 57M| 0 |00:00:00.01 | |* 14 | COUNT STOPKEY | | 64 | | 4169K|00:05:45.40 | | 15 | PX BLOCK ITERATOR | | 64 | 57M| 4169K|00:05:42.68 | |* 16 | TABLE ACCESS FULL | OE_ORDER_LINES_ALL | 233 | 57M| 4169K|00:05:26.98 | ----------------------------------------------------------------------------------------------------

Predicate Information (identified by operation id): --------------------------------------------------- ..

Note -----


ALLSTATS

After 4 executions with DOP=16


Note section

Note ----- - dynamic sampling used for this statement (level=2)

Note ----- - SQL profile “SQL_PROF_4awcsbtwr8ksz" used for this statement

Note ----- - Cardinality feedback used


Few limitations

  Display_awr does not store predicates.

  Of course , not all SQL statements are stored in AWR repository (color important statements).

  Display_cursor is not RAC aware. You can query the plans only from the local instances using display_cursor.

  Run time statistics are printed only after the completion of SQL statements (Think production long running queries).


SQL monitor

SET LONG 1000000 SET LONGCHUNKSIZE 1000000 SET LINESIZE 1000 SET PAGESIZE 0 SET TRIM ON SET TRIMSPOOL ON SET ECHO OFF SET FEEDBACK OFF

SELECT DBMS_SQLTUNE.report_sql_monitor( sql_id => '&sql_id', type=>'TEXT' , report_level => 'ALL') from dual /


Output


Output ..2


Me

  19 years using Oracle products/DBA

  OakTable member

  Oracle ACE Director

  Certified DBA versions 7.0,7.3,8,8i,9i &10g

  Specializes in RAC, performance tuning, Internals and E-business suite

  Chief DBA with OraInternals

  Co-author few books

  Email: [email protected]

  Blog : orainternals.wordpress.com

  Web: www.orainternals.com


Thank you for attending!

If you like this presentation, you will love my 2-part intensive, online RAC webinar.

http://www.orainternals.com/training/advanced-rac-training

Email: [email protected]

Week Dates Time

Week1 TBA 8AM – 2PM PDT

Week 2 TBA 8AM - 2PM PDT


References

•   Oracle support site. Metalink.oracle.com. Various documents •   Troubleshooting Oracle performance - Christian Antongini •   http://www.orainternals.com/papers - Riyaj Shamsudeen •   Various article from web led through on google search •   Tom Kyte’s website Asktom.oracle.com

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