dbms plan - a swiss army knife for performance engineers

dbms_xplan: A Swiss army knife for performance engineers

Sahil Thapar

Riyaj Shamsudeen

2

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.

3

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_DATEPARSE:#1844674:c=10000,e=10162,p=0,cr=0,cu=0,mis=1,r=0,dep=0,og=1,plh=3298327531,tim=7861072491386EXEC:#1844674:c=0,e=139,p=0,cr=0,cu=0,mis=0,r=0,dep=0,og=1,plh=3298327531,tim=7861072491723EXEC:#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=786107FETCH#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)'

4

Raw trace fileContent of a sql trace file:

5

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 0Execute 1 0.00 0.00 0 0 0 0Fetch 1 18.02 59.60 199262 199331 0 0------- ------ -------- ---------- ---------- ---------- ---------- ----------total 3 18.03 59.61 199262 199331 0 0

6

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

7

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)

8

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.

9

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

Formatselect * 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 combination:TYPICAL is the default class

SQL_ID 9sup9gfhhg32t, child number 0-------------------------------------SELECT RECID, TABLENAME, PROJECT_NUMBER, PROJECT_NAME,……………………………………………………………………………………………LEDIT_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

10

dbms_xplan.display

Optimizer estimates

11

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

12

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-----

13

Privileges

For dbms_xplan.display_awrgrant select on dba_hist_sqltext to scottgrant select on dba_hist_sql_plan to scott;grant select on v_$database to scott;ORSELECT_CATALOG role

Privileges needed to execute dbms_xplan

For dbms_xplan.display_cursorgrant 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;ORSELECT_CATALOG role or select any dictionary system privilege

14

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_numberfrom 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_OUTPUTFROM TABLE(CAST(DBMS_XPLAN.PREPARE_RECORDS(:B1 , :B2 ) AS SYS.DBMS_XPLAN_TYPE_TABLE))

Really complicated recursive SQL statements!

15

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_tmpfrom 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

16

How do I tune?

my_sql.sqlSet linesize 300;set pagesize 1000;--Declare variable and assign valuesvar order_id number;execute :order_id:=53759119SELECT 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.

17

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_OUTPUTSQL_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 | | |---------------------------------------------------------------------------------------------------------------------------

18

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

19

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)

20

dbms_xplan: access and filter predicatesAdded a predicate oel.open_flag=‘Y’

21

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

22

dbms_xplan: script

--my_sql.sql script_nameset linesize 300;set pagesize 1000;--Declare variable and assign valuesvar order_id number;execute order_id:=53759119alter session set statistics_level=‘ALL’; --OR ADD HINTSELECT /*+ gather_plan_statistics */ oeh.header_id, oel.line_idFROM oe_order_headers_all oeh, oe_order_lines_all oelWHERE oeh.header_id = :order_id AND oeh.header_id = oel.header_id/

Modify the script to enable extended execution statistics

23

Execution statistics

SQL_ID 7gftgf917tg2x, child number 0-------------------------------------select /*+ gather_plan_statistics */ oeh.header_id,oel.line_id fromoe_order_headers_all oeh,oe_order_lines_all oel whereoeh.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'))/

24

Alias

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

SELECT /*+ gather_plan_statistics */ oel.line_id FROMoe_order_lines_all oel WHERE oel.open_flag = 'Y' andexists (select 1 from oe_order_headers_all oeh whereoeh.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

25

Query Block name

26

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

27

Hints or Outlines

set linesize 300set pagesize 300alter 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 */

28

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 */

29

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 300set pagesize 300alter 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 DescriptionAlways available columns

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

Operation Row source operationName The database object in the operationCBO parse time information

RowsEstimated 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 operationTempSpc The estimated amount of temp space usage by the operationCost(%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:SSPartitioningPstart Number of first partition to be accessedPstop The number of last partition to be accessedParallel ProcessingTQ Table queue used for processingIN-OUT The relation between parallel operationsPQ Distrib The distribution used by producers to send data to consumersRuntime StatisticsStarts The number of times operation was executed (check more nested loop joins operation)A-Rows Actual number of rows returnedA-Time Actual amount of time spent executing the operationI/O Statistics Buffers Logical reads operations performed during execution of each stepRead Physical reads performed for each operationWrite Physical writes performed

33

dbms_xplan.display_awr

Formatselect * 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)) fromorder_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 |---------------------------------------------------------------------------


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 ohWHERE 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 ohWHERE 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' ) olWHERE 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 cardinalityFeedback.


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 1000000SET LONGCHUNKSIZE 1000000SET LINESIZE 1000SET PAGESIZE 0SET TRIM ONSET TRIMSPOOL ONSET ECHO OFFSET FEEDBACK OFFSELECT DBMS_SQLTUNE.report_sql_monitor( sql_id => '&sql_id', type=>'TEXT' , report_level => 'ALL') from dual/


Output


Output ..2

53

A Presentation sponsored by


Riyaj Shamsudeen

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] 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

dbms plan - a swiss army knife for performance engineers

Technology

xadvanced x

table dbms

tasks cr

view cr

projects cr

cpu time

cursor real plan

sort unique cr