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Oracle Query Tuning Tips - Get it Right the First Time

Dean Richards, profile picture
Dean Richards

The document is a presentation by Dean Richards on SQL query tuning for Oracle, emphasizing the importance of optimizing SQL queries to enhance database performance. It discusses the roles of developers and DBAs in tuning, highlights which queries to focus on, and provides case studies illustrating practical tuning techniques and execution plans. Key tools and methods, including the use of the Oracle wait interface and dbms_xplan for execution plans, are also covered.

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SQL Query Tuning Tips for Oracle Get it Right the First Time Dean Richards Lead DBA, Confio Software 2/21/2013 1
2/21/2013 Confidential - Internal Use Only 2 Who Am I? • 20+ Years in Oracle & SQL Server – DBA and Developer – Worked for Oracle SPG • Lead DBA for Confio Software – DeanRichards@confio.com – Makers of Ignite8 Response Time Analysis Tools – http://www.ignitefree.com – only free RTA Tool • Specialize in Performance Tuning
2/21/2013 3 Agenda • Introduction • Which Query Should I Tune? • Query Plans • SQL Diagramming – Who registered yesterday for Tuning Class – Check order status
2/21/2013 Confidential - Internal Use Only 4 Why Focus on Queries • Most Applications – Read and Write data to/from database – Simple manipulation of data – Deal with smaller amounts of data • Most Databases – Examine larger amounts of data, return a little – Inefficiencies quickly become bottleneck • Why do SQL tuning? – Tuning SQL - “Gives the most bang for your buck” – Changes to SQL are Safer – ~85% of performance issues are SQL related
2/21/2013 Confidential - Internal Use Only 5 Who Should Tune • Developers? – Developing applications is very difficult – Typically focused on functionality – Not much time left to tune SQL – Do not get enough practice – SQL runs differently in Production than Dev/Test • DBA? – Do not know the code like developers do – Focus on “Keep the Lights On” – Very complex environment • Need a team approach – But also need someone to lead the effort
2/21/2013 Confidential - Internal Use Only 6 Which SQL • User / Batch Job Complaints • Queries Performing Most I/O (LIO, PIO) • Queries Consuming CPU • Queries Doing Full Table Scans • Known Poorly Performing SQL • Tracing a Session / Process • Highest Response Times (Ignite for Oracle) select sql_text, elapsed_time, cpu_time, executions, sql_id, hash_value, last_active_time, plan_hash_value, program_id, module, action from v$sql order by elapsed_time /
2/21/2013 Confidential - Internal Use Only 7 SQL Wait States  Understand the total time a Query spends in Database  Measure time while Query executes  SQL Server helps by providing Wait Types Focus on Response Time
2/21/2013 Confidential - Internal Use Only 8 Oracle Wait Interface V$SQL SQL_ID SQL_FULLTEXT V$SESSION SID USERNAME SQL_ID PROGRAM MODULE ACTION PLAN_HASH_VALUE ROW_WAIT_OBJ# V$SQLAREA SQL_ID EXECUTIONS PARSE_CALLS BUFFER_GETS DISK_READS V$SESSION_WAIT SID EVENT P1, P1RAW, P2, P2RAW, P3, P3RAW STATE (WAITING, WAITED…) • Oracle 10g added this info to V$SESSION V$SQL_PLAN SQL_ID PLAN_HASH_VALUE DBA_OBJECTS OBJECT_ID OBJECT_NAME OBJECT_TYPE
2/21/2013 Confidential - Internal Use Only 9 Oracle Wait Interface SELECT s.sql_id, sql.sql_text, sql.plan_hash_value, DECODE(s.state, 'WAITING', s.event, 'CPU/LogicalIO') waitevent, s.p1, s.p2, s.p3 FROM v$session s, v$sql sql WHERE s.sql_id = sql.sql_id AND s.sql_address = sql.address AND program = ‘…’ AND s.sid = … AND <whatever else you know>
2/21/2013 Confidential - Internal Use Only 10 SQL Plan • EXPLAIN PLAN – Estimated execution plan – Can be wrong for many reasons – What most tools show you • V$SQL_PLAN (Oracle 9i+) – Real execution plan – Use DBMS_XPLAN for display • Confio Ignite for Oracle – Gathers real plan – Shows it historically
2/21/2013 Confidential - Internal Use Only 11 DBMS_XPLAN select * from table ( dbms_xplan.display_cursor(‘&SQLID’,ChildNo)); PLAN_TABLE_OUTPUT -------------------------------------------------------------------------------- SQL_ID f7jqysdfu2f2s, child number 0 ------------------------------------- update emp set hire_date = to_date(':1') where id=:2 Plan hash value: 1494045816 --------------------------------------------------------------------------- | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | --------------------------------------------------------------------------- | 0 | UPDATE STATEMENT | | | | 3025 (100)| | | 1 | UPDATE | EMP | | | | | |* 2 | TABLE ACCESS FULL| EMP | 122 | 2684 | 3025 (1)| 00:00:37 | --------------------------------------------------------------------------- Predicate Information (identified by operation id): --------------------------------------------------- 2 - filter("ID"=3247)
2/21/2013 Confidential - Internal Use Only 12 All Plans Not Equal SELECT company, attribute FROM data_out WHERE segment = :B1 • Wait Time – 100% on “db file scattered read” • Plan from EXPLAIN PLAN • Plan from V$SQL_PLAN using DBMS_XPLAN
2/21/2013 Confidential - Internal Use Only 13 Bind Values • V$SQL_BIND_CAPTURE – STATISTICS_LEVEL = TYPICAL or ALL – Collected at 15 minute intervals SELECT name, position, datatype_string, value_string FROM v$sql_bind_capture WHERE sql_id = '15uughacxfh13'; NAME POSITION DATATYPE_STRING VALUE_STRING ----- ---------- --------------- ------------ :B1 1 BINARY_DOUBLE 189 • Bind Values also provided by tracing – Level 4 – bind values – Level 8 – wait information – Level 12 – bind values and wait information
2/21/2013 Confidential - Internal Use Only 14 Case Studies • SQL Diagramming • Case Study 1 – Who registered for Tuning Class yesterday • Case Study 2 – Check order status
2/21/2013 Confidential - Internal Use Only 15 Case Study 1 • Who registered yesterday for SQL Tuning SELECT s.fname, s.lname, r.signup_date FROM student s INNER JOIN registration r ON s.student_id = r.student_id INNER JOIN class c ON r.class_id = c.class_id WHERE c.name = 'SQL TUNING' AND r.signup_date BETWEEN :1 AND :2 AND r.cancelled = 'N' • Execution Stats – 12,634 Logical Reads
2/21/2013 Confidential - Internal Use Only 16 Database Diagram
2/21/2013 Confidential - Internal Use Only 17 Execution Plan ---------------------------------------------------------------------------------------------- | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | ---------------------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 7 | 819 | 3173 (5)| 00:00:39 | |* 1 | FILTER | | | | | | | 2 | NESTED LOOPS | | | | | | | 3 | NESTED LOOPS | | 7 | 819 | 3173 (5)| 00:00:39 | |* 4 | HASH JOIN | | 7 | 448 | 3166 (5)| 00:00:38 | |* 5 | TABLE ACCESS FULL | CLASS | 1 | 45 | 22 (0)| 00:00:01 | |* 6 | TABLE ACCESS FULL | REGISTRATION | 8334 | 154K| 3144 (5)| 00:00:38 | |* 7 | INDEX UNIQUE SCAN | PK_STUDENT | 1 | | 0 (0)| 00:00:01 | | 8 | TABLE ACCESS BY INDEX ROWID| STUDENT | 1 | 53 | 1 (0)| 00:00:01 | ---------------------------------------------------------------------------------------------- Predicate Information (identified by operation id): --------------------------------------------------- 1 - filter(TRUNC(SYSDATE@!-1)<=TRUNC(SYSDATE@!)) 4 - access("R"."CLASS_ID"="C"."CLASS_ID") 5 - filter("C"."NAME"='SQL TUNING') 6 - filter("R"."SIGNUP_DATE">=TRUNC(SYSDATE@!-1) AND "R"."CANCELLED"='N' AND "R"."SIGNUP_DATE"<=TRUNC(SYSDATE@!)) 7 - access("S"."STUDENT_ID"="R"."STUDENT_ID")
2/21/2013 Confidential - Internal Use Only 18 SQL Diagramming registration student class 5 1 30 1 .03 .001 select count(1) from registration where cancelled = 'N' and signup_date between '2012-12-05 00:00' and '2012-12-06 00:00' 54,554 / 1,639,186 = 0.03 select count(1) from class where name = 'SQL TUNING' 2 / 1,267 = .001 • Great Book - “SQL Tuning” by Dan Tow – Teaches SQL Diagramming – http://www.singingsql.com
2/21/2013 Confidential - Internal Use Only 19 New Execution Plan • Execution Stats – 11,168 Logical Reads • Why does a Full Table Scan still occur on REGISTRATION? ------------------------------------------------------------------------------------------------ | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | ------------------------------------------------------------------------------------------------ | 0 | SELECT STATEMENT | | 7 | 819 | 3153 (5)| 00:00:38 | |* 1 | FILTER | | | | | | | 2 | NESTED LOOPS | | | | | | | 3 | NESTED LOOPS | | 7 | 819 | 3153 (5)| 00:00:38 | |* 4 | HASH JOIN | | 7 | 448 | 3146 (5)| 00:00:38 | | 5 | TABLE ACCESS BY INDEX ROWID| CLASS | 1 | 45 | 2 (0)| 00:00:01 | |* 6 | INDEX RANGE SCAN | CL_NAME | 1 | | 1 (0)| 00:00:01 | |* 7 | TABLE ACCESS FULL | REGISTRATION | 8334 | 154K| 3144 (5)| 00:00:38 | |* 8 | INDEX UNIQUE SCAN | PK_STUDENT | 1 | | 0 (0)| 00:00:01 | | 9 | TABLE ACCESS BY INDEX ROWID | STUDENT | 1 | 53 | 1 (0)| 00:00:01 | ------------------------------------------------------------------------------------------------ CREATE INDEX cl_name ON class(name)
2/21/2013 Confidential - Internal Use Only 20 Database Diagram
2/21/2013 Confidential - Internal Use Only 21 New Execution Plan CREATE INDEX reg_alt ON registration(class_id) • Execution Stats – 4,831 Logical Reads ------------------------------------------------------------------------------------------------ | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | ------------------------------------------------------------------------------------------------ | 0 | SELECT STATEMENT | | 7 | 819 | 2415 (1)| 00:00:29 | |* 1 | FILTER | | | | | | | 2 | NESTED LOOPS | | | | | | | 3 | NESTED LOOPS | | 7 | 819 | 2415 (1)| 00:00:29 | | 4 | NESTED LOOPS | | 7 | 448 | 2408 (1)| 00:00:29 | | 5 | TABLE ACCESS BY INDEX ROWID| CLASS | 1 | 45 | 2 (0)| 00:00:01 | |* 6 | INDEX RANGE SCAN | CL_NAME | 1 | | 1 (0)| 00:00:01 | |* 7 | TABLE ACCESS BY INDEX ROWID| REGISTRATION | 7 | 133 | 2406 (1)| 00:00:29 | |* 8 | INDEX RANGE SCAN | REG_ALT | 2667 | | 9 (0)| 00:00:01 | |* 9 | INDEX UNIQUE SCAN | PK_STUDENT | 1 | | 0 (0)| 00:00:01 | | 10 | TABLE ACCESS BY INDEX ROWID | STUDENT | 1 | 53 | 1 (0)| 00:00:01 | ------------------------------------------------------------------------------------------------
2/21/2013 Confidential - Internal Use Only 22 Case Study 2 • Lookup order status for caller SELECT o.OrderID, c.LastName, p.ProductID, p.Description, sd.ActualShipDate, sd.ShipStatus, sd.ExpectedShipDate FROM Orders o INNER JOIN Item i ON i.OrderID = o.OrderID INNER JOIN Customer c ON c.CustomerID = o.CustomerID INNER JOIN ShipmentDetails sd ON sd.ShipmentID = i.ShipmentID INNER JOIN Product p ON p.ProductID = i.ProductID INNER JOIN Address a ON a.AddressID = sd.AddressID WHERE c.LastName LIKE NVL(:1,'') || '%' AND c.FirstName LIKE NVL(:2,'') || '%' AND o.OrderDate >= SYSDATE - 30 AND o.OrderStatus <> 'C' • Execution Stats – 73,600 Logical Reads
2/21/2013 Confidential - Internal Use Only 23 Case Study 2 • Lookup order status for caller SELECT o.OrderID, c.LastName, p.ProductID, p.Description, sd.ActualShipDate, sd.ShipStatus, sd.ExpectedShipDate FROM Orders o INNER JOIN Item i ON i.OrderID = o.OrderID INNER JOIN Customer c ON c.CustomerID = o.CustomerID INNER JOIN ShipmentDetails sd ON sd.ShipmentID = i.ShipmentID INNER JOIN Product p ON p.ProductID = i.ProductID INNER JOIN Address a ON a.AddressID = sd.AddressID WHERE c.LastName LIKE 'SMI%' AND c.FirstName LIKE '%' AND o.OrderDate >= SYSDATE - 30 AND o.OrderStatus <> 'C' • Execution Stats – 73,600 Logical Reads
2/21/2013 Confidential - Internal Use Only 24 Database Diagram
2/21/2013 Confidential - Internal Use Only 25 -------------------------------------------------------------------------------------------------- | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | -------------------------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 6 | 1164 | 4892 (2)| 00:00:59 | | 1 | NESTED LOOPS | | | | | | | 2 | NESTED LOOPS | | 6 | 1164 | 4892 (2)| 00:00:59 | | 3 | NESTED LOOPS | | 6 | 510 | 4886 (2)| 00:00:59 | |* 4 | HASH JOIN | | 105 | 5460 | 4782 (2)| 00:00:58 | |* 5 | HASH JOIN | | 1320 | 44880 | 4118 (2)| 00:00:50 | |* 6 | TABLE ACCESS FULL | SHIPMENTDETAILS | 304 | 6080 | 1070 (2)| 00:00:13 | | 7 | TABLE ACCESS FULL | ITEM | 3588K| 47M| 3036 (1)| 00:00:37 | |* 8 | TABLE ACCESS FULL | ORDERS | 54903 | 965K| 663 (3)| 00:00:08 | |* 9 | TABLE ACCESS BY INDEX ROWID| CUSTOMER | 1 | 33 | 1 (0)| 00:00:01 | |* 10 | INDEX UNIQUE SCAN | PK_CUSTOMER | 1 | | 0 (0)| 00:00:01 | |* 11 | INDEX UNIQUE SCAN | PK_PRODUCT | 1 | | 0 (0)| 00:00:01 | | 12 | TABLE ACCESS BY INDEX ROWID | PRODUCT | 1 | 109 | 1 (0)| 00:00:01 | -------------------------------------------------------------------------------------------------- Predicate Information (identified by operation id): --------------------------------------------------- 4 - access("I"."ORDERID"="O"."ORDERID") 5 - access("SD"."SHIPMENTID"="I"."SHIPMENTID") 6 - filter("SD"."SHIPSTATUS"<>'C') 8 - filter("O"."ORDERDATE">=SYSDATE@!-30) 9 - filter("C"."LASTNAME" LIKE 'SMI%') 10 - access("C"."CUSTOMERID"="O"."CUSTOMERID") 11 - access("P"."PRODUCTID"="I"."PRODUCTID") Execution Plan
2/21/2013 Confidential - Internal Use Only 26 SELECT COUNT(1) FROM Customer WHERE LastName LIKE 'SMI%' 1917 / 52189 = .04 SELECT COUNT(1) FROM Orders WHERE OrderDate >= SYSDATE - 30 55067 / 690671 = .08 SELECT COUNT(1) FROM Orders WHERE OrderStatus <> 'C' 3760 / 690671 = .005 o .08 .04i c psd a .005 SQL Diagram
2/21/2013 Confidential - Internal Use Only 27 • Only 0.5% of rows are <> ‘C’ • How about changing the query? – AND o.OrderStatus = 'I' • Add an Index on OrderStatus – Collect histograms SELECT OrderStatus, COUNT(1) FROM Orders GROUP BY OrderStatus I 3760 C 686911 Data Skew Problems
2/21/2013 Confidential - Internal Use Only 28 New Execution Plan CREATE INDEX order_status ON Orders (OrderStatus) Execution Stats – 7,221 Logical Reads ----------------------------------------------------------------------------------------------------- | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | ----------------------------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 1581 | 301K| 3722 (1)| 00:00:45 | |* 1 | HASH JOIN | | 1581 | 301K| 3722 (1)| 00:00:45 | |* 2 | HASH JOIN | | 1581 | 270K| 2655 (1)| 00:00:32 | | 3 | NESTED LOOPS | | | | | | | 4 | NESTED LOOPS | | 1581 | 101K| 2587 (1)| 00:00:32 | |* 5 | HASH JOIN | | 303 | 15756 | 170 (1)| 00:00:03 | |* 6 | TABLE ACCESS BY INDEX ROWID| ORDERS | 303 | 5757 | 33 (0)| 00:00:01 | |* 7 | INDEX RANGE SCAN | ORDER_STATUS | 3811 | | 9 (0)| 00:00:01 | |* 8 | VIEW | index$_join$_001 | 2055 | 67815 | 137 (1)| 00:00:02 | |* 9 | HASH JOIN | | | | | | |* 10 | INDEX RANGE SCAN | CUSTOMER_LN | 2055 | 67815 | 14 (8)| 00:00:01 | | 11 | INDEX FAST FULL SCAN | PK_CUSTOMER | 2055 | 67815 | 123 (0)| 00:00:02 | |* 12 | INDEX RANGE SCAN | PK_ORDERINFO | 5 | | 2 (0)| 00:00:01 | | 13 | TABLE ACCESS BY INDEX ROWID | ITEM | 5 | 70 | 8 (0)| 00:00:01 | | 14 | TABLE ACCESS FULL | PRODUCT | 8914 | 948K| 68 (0)| 00:00:01 | | 15 | TABLE ACCESS FULL | SHIPMENTDETAILS | 836K| 15M| 1064 (1)| 00:00:13 | -----------------------------------------------------------------------------------------------------
2/21/2013 Confidential - Internal Use Only 29 • Tuning SQL gives more “bang for the buck” • Make sure you are tuning the correct query • Use Wait Events and Response Time Analysis – Locking problems may not be a Query Tuning issue – Wait events tell you where to start • Use “Real Execution Plans” – Get plan_hash_value from V$SESSION, V$SQL – Pass it to V$SQL_PLAN to get Real Plan • Ignite – Does All of Above For You – OEM Does not Give you Enough Details • SQL Diagramming - “Get it right the First Time” Takeaway Points
Q&A Thank you for attending. More questions? Contact Dean at DeanRichards@confio.com Download free trial of Ignite at http//www.confio.com 2/21/2013 30

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Oracle Query Tuning Tips - Get it Right the First Time

  • 1. SQL Query Tuning Tips for Oracle Get it Right the First Time Dean Richards Lead DBA, Confio Software 2/21/2013 1
  • 2. 2/21/2013 Confidential - Internal Use Only 2 Who Am I? • 20+ Years in Oracle & SQL Server – DBA and Developer – Worked for Oracle SPG • Lead DBA for Confio Software – DeanRichards@confio.com – Makers of Ignite8 Response Time Analysis Tools – http://www.ignitefree.com – only free RTA Tool • Specialize in Performance Tuning
  • 3. 2/21/2013 3 Agenda • Introduction • Which Query Should I Tune? • Query Plans • SQL Diagramming – Who registered yesterday for Tuning Class – Check order status
  • 4. 2/21/2013 Confidential - Internal Use Only 4 Why Focus on Queries • Most Applications – Read and Write data to/from database – Simple manipulation of data – Deal with smaller amounts of data • Most Databases – Examine larger amounts of data, return a little – Inefficiencies quickly become bottleneck • Why do SQL tuning? – Tuning SQL - “Gives the most bang for your buck” – Changes to SQL are Safer – ~85% of performance issues are SQL related
  • 5. 2/21/2013 Confidential - Internal Use Only 5 Who Should Tune • Developers? – Developing applications is very difficult – Typically focused on functionality – Not much time left to tune SQL – Do not get enough practice – SQL runs differently in Production than Dev/Test • DBA? – Do not know the code like developers do – Focus on “Keep the Lights On” – Very complex environment • Need a team approach – But also need someone to lead the effort
  • 6. 2/21/2013 Confidential - Internal Use Only 6 Which SQL • User / Batch Job Complaints • Queries Performing Most I/O (LIO, PIO) • Queries Consuming CPU • Queries Doing Full Table Scans • Known Poorly Performing SQL • Tracing a Session / Process • Highest Response Times (Ignite for Oracle) select sql_text, elapsed_time, cpu_time, executions, sql_id, hash_value, last_active_time, plan_hash_value, program_id, module, action from v$sql order by elapsed_time /
  • 7. 2/21/2013 Confidential - Internal Use Only 7 SQL Wait States  Understand the total time a Query spends in Database  Measure time while Query executes  SQL Server helps by providing Wait Types Focus on Response Time
  • 8. 2/21/2013 Confidential - Internal Use Only 8 Oracle Wait Interface V$SQL SQL_ID SQL_FULLTEXT V$SESSION SID USERNAME SQL_ID PROGRAM MODULE ACTION PLAN_HASH_VALUE ROW_WAIT_OBJ# V$SQLAREA SQL_ID EXECUTIONS PARSE_CALLS BUFFER_GETS DISK_READS V$SESSION_WAIT SID EVENT P1, P1RAW, P2, P2RAW, P3, P3RAW STATE (WAITING, WAITED…) • Oracle 10g added this info to V$SESSION V$SQL_PLAN SQL_ID PLAN_HASH_VALUE DBA_OBJECTS OBJECT_ID OBJECT_NAME OBJECT_TYPE
  • 9. 2/21/2013 Confidential - Internal Use Only 9 Oracle Wait Interface SELECT s.sql_id, sql.sql_text, sql.plan_hash_value, DECODE(s.state, 'WAITING', s.event, 'CPU/LogicalIO') waitevent, s.p1, s.p2, s.p3 FROM v$session s, v$sql sql WHERE s.sql_id = sql.sql_id AND s.sql_address = sql.address AND program = ‘…’ AND s.sid = … AND <whatever else you know>
  • 10. 2/21/2013 Confidential - Internal Use Only 10 SQL Plan • EXPLAIN PLAN – Estimated execution plan – Can be wrong for many reasons – What most tools show you • V$SQL_PLAN (Oracle 9i+) – Real execution plan – Use DBMS_XPLAN for display • Confio Ignite for Oracle – Gathers real plan – Shows it historically
  • 11. 2/21/2013 Confidential - Internal Use Only 11 DBMS_XPLAN select * from table ( dbms_xplan.display_cursor(‘&SQLID’,ChildNo)); PLAN_TABLE_OUTPUT -------------------------------------------------------------------------------- SQL_ID f7jqysdfu2f2s, child number 0 ------------------------------------- update emp set hire_date = to_date(':1') where id=:2 Plan hash value: 1494045816 --------------------------------------------------------------------------- | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | --------------------------------------------------------------------------- | 0 | UPDATE STATEMENT | | | | 3025 (100)| | | 1 | UPDATE | EMP | | | | | |* 2 | TABLE ACCESS FULL| EMP | 122 | 2684 | 3025 (1)| 00:00:37 | --------------------------------------------------------------------------- Predicate Information (identified by operation id): --------------------------------------------------- 2 - filter("ID"=3247)
  • 12. 2/21/2013 Confidential - Internal Use Only 12 All Plans Not Equal SELECT company, attribute FROM data_out WHERE segment = :B1 • Wait Time – 100% on “db file scattered read” • Plan from EXPLAIN PLAN • Plan from V$SQL_PLAN using DBMS_XPLAN
  • 13. 2/21/2013 Confidential - Internal Use Only 13 Bind Values • V$SQL_BIND_CAPTURE – STATISTICS_LEVEL = TYPICAL or ALL – Collected at 15 minute intervals SELECT name, position, datatype_string, value_string FROM v$sql_bind_capture WHERE sql_id = '15uughacxfh13'; NAME POSITION DATATYPE_STRING VALUE_STRING ----- ---------- --------------- ------------ :B1 1 BINARY_DOUBLE 189 • Bind Values also provided by tracing – Level 4 – bind values – Level 8 – wait information – Level 12 – bind values and wait information
  • 14. 2/21/2013 Confidential - Internal Use Only 14 Case Studies • SQL Diagramming • Case Study 1 – Who registered for Tuning Class yesterday • Case Study 2 – Check order status
  • 15. 2/21/2013 Confidential - Internal Use Only 15 Case Study 1 • Who registered yesterday for SQL Tuning SELECT s.fname, s.lname, r.signup_date FROM student s INNER JOIN registration r ON s.student_id = r.student_id INNER JOIN class c ON r.class_id = c.class_id WHERE c.name = 'SQL TUNING' AND r.signup_date BETWEEN :1 AND :2 AND r.cancelled = 'N' • Execution Stats – 12,634 Logical Reads
  • 16. 2/21/2013 Confidential - Internal Use Only 16 Database Diagram
  • 17. 2/21/2013 Confidential - Internal Use Only 17 Execution Plan ---------------------------------------------------------------------------------------------- | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | ---------------------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 7 | 819 | 3173 (5)| 00:00:39 | |* 1 | FILTER | | | | | | | 2 | NESTED LOOPS | | | | | | | 3 | NESTED LOOPS | | 7 | 819 | 3173 (5)| 00:00:39 | |* 4 | HASH JOIN | | 7 | 448 | 3166 (5)| 00:00:38 | |* 5 | TABLE ACCESS FULL | CLASS | 1 | 45 | 22 (0)| 00:00:01 | |* 6 | TABLE ACCESS FULL | REGISTRATION | 8334 | 154K| 3144 (5)| 00:00:38 | |* 7 | INDEX UNIQUE SCAN | PK_STUDENT | 1 | | 0 (0)| 00:00:01 | | 8 | TABLE ACCESS BY INDEX ROWID| STUDENT | 1 | 53 | 1 (0)| 00:00:01 | ---------------------------------------------------------------------------------------------- Predicate Information (identified by operation id): --------------------------------------------------- 1 - filter(TRUNC(SYSDATE@!-1)<=TRUNC(SYSDATE@!)) 4 - access("R"."CLASS_ID"="C"."CLASS_ID") 5 - filter("C"."NAME"='SQL TUNING') 6 - filter("R"."SIGNUP_DATE">=TRUNC(SYSDATE@!-1) AND "R"."CANCELLED"='N' AND "R"."SIGNUP_DATE"<=TRUNC(SYSDATE@!)) 7 - access("S"."STUDENT_ID"="R"."STUDENT_ID")
  • 18. 2/21/2013 Confidential - Internal Use Only 18 SQL Diagramming registration student class 5 1 30 1 .03 .001 select count(1) from registration where cancelled = 'N' and signup_date between '2012-12-05 00:00' and '2012-12-06 00:00' 54,554 / 1,639,186 = 0.03 select count(1) from class where name = 'SQL TUNING' 2 / 1,267 = .001 • Great Book - “SQL Tuning” by Dan Tow – Teaches SQL Diagramming – http://www.singingsql.com
  • 19. 2/21/2013 Confidential - Internal Use Only 19 New Execution Plan • Execution Stats – 11,168 Logical Reads • Why does a Full Table Scan still occur on REGISTRATION? ------------------------------------------------------------------------------------------------ | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | ------------------------------------------------------------------------------------------------ | 0 | SELECT STATEMENT | | 7 | 819 | 3153 (5)| 00:00:38 | |* 1 | FILTER | | | | | | | 2 | NESTED LOOPS | | | | | | | 3 | NESTED LOOPS | | 7 | 819 | 3153 (5)| 00:00:38 | |* 4 | HASH JOIN | | 7 | 448 | 3146 (5)| 00:00:38 | | 5 | TABLE ACCESS BY INDEX ROWID| CLASS | 1 | 45 | 2 (0)| 00:00:01 | |* 6 | INDEX RANGE SCAN | CL_NAME | 1 | | 1 (0)| 00:00:01 | |* 7 | TABLE ACCESS FULL | REGISTRATION | 8334 | 154K| 3144 (5)| 00:00:38 | |* 8 | INDEX UNIQUE SCAN | PK_STUDENT | 1 | | 0 (0)| 00:00:01 | | 9 | TABLE ACCESS BY INDEX ROWID | STUDENT | 1 | 53 | 1 (0)| 00:00:01 | ------------------------------------------------------------------------------------------------ CREATE INDEX cl_name ON class(name)
  • 20. 2/21/2013 Confidential - Internal Use Only 20 Database Diagram
  • 21. 2/21/2013 Confidential - Internal Use Only 21 New Execution Plan CREATE INDEX reg_alt ON registration(class_id) • Execution Stats – 4,831 Logical Reads ------------------------------------------------------------------------------------------------ | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | ------------------------------------------------------------------------------------------------ | 0 | SELECT STATEMENT | | 7 | 819 | 2415 (1)| 00:00:29 | |* 1 | FILTER | | | | | | | 2 | NESTED LOOPS | | | | | | | 3 | NESTED LOOPS | | 7 | 819 | 2415 (1)| 00:00:29 | | 4 | NESTED LOOPS | | 7 | 448 | 2408 (1)| 00:00:29 | | 5 | TABLE ACCESS BY INDEX ROWID| CLASS | 1 | 45 | 2 (0)| 00:00:01 | |* 6 | INDEX RANGE SCAN | CL_NAME | 1 | | 1 (0)| 00:00:01 | |* 7 | TABLE ACCESS BY INDEX ROWID| REGISTRATION | 7 | 133 | 2406 (1)| 00:00:29 | |* 8 | INDEX RANGE SCAN | REG_ALT | 2667 | | 9 (0)| 00:00:01 | |* 9 | INDEX UNIQUE SCAN | PK_STUDENT | 1 | | 0 (0)| 00:00:01 | | 10 | TABLE ACCESS BY INDEX ROWID | STUDENT | 1 | 53 | 1 (0)| 00:00:01 | ------------------------------------------------------------------------------------------------
  • 22. 2/21/2013 Confidential - Internal Use Only 22 Case Study 2 • Lookup order status for caller SELECT o.OrderID, c.LastName, p.ProductID, p.Description, sd.ActualShipDate, sd.ShipStatus, sd.ExpectedShipDate FROM Orders o INNER JOIN Item i ON i.OrderID = o.OrderID INNER JOIN Customer c ON c.CustomerID = o.CustomerID INNER JOIN ShipmentDetails sd ON sd.ShipmentID = i.ShipmentID INNER JOIN Product p ON p.ProductID = i.ProductID INNER JOIN Address a ON a.AddressID = sd.AddressID WHERE c.LastName LIKE NVL(:1,'') || '%' AND c.FirstName LIKE NVL(:2,'') || '%' AND o.OrderDate >= SYSDATE - 30 AND o.OrderStatus <> 'C' • Execution Stats – 73,600 Logical Reads
  • 23. 2/21/2013 Confidential - Internal Use Only 23 Case Study 2 • Lookup order status for caller SELECT o.OrderID, c.LastName, p.ProductID, p.Description, sd.ActualShipDate, sd.ShipStatus, sd.ExpectedShipDate FROM Orders o INNER JOIN Item i ON i.OrderID = o.OrderID INNER JOIN Customer c ON c.CustomerID = o.CustomerID INNER JOIN ShipmentDetails sd ON sd.ShipmentID = i.ShipmentID INNER JOIN Product p ON p.ProductID = i.ProductID INNER JOIN Address a ON a.AddressID = sd.AddressID WHERE c.LastName LIKE 'SMI%' AND c.FirstName LIKE '%' AND o.OrderDate >= SYSDATE - 30 AND o.OrderStatus <> 'C' • Execution Stats – 73,600 Logical Reads
  • 24. 2/21/2013 Confidential - Internal Use Only 24 Database Diagram
  • 25. 2/21/2013 Confidential - Internal Use Only 25 -------------------------------------------------------------------------------------------------- | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | -------------------------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 6 | 1164 | 4892 (2)| 00:00:59 | | 1 | NESTED LOOPS | | | | | | | 2 | NESTED LOOPS | | 6 | 1164 | 4892 (2)| 00:00:59 | | 3 | NESTED LOOPS | | 6 | 510 | 4886 (2)| 00:00:59 | |* 4 | HASH JOIN | | 105 | 5460 | 4782 (2)| 00:00:58 | |* 5 | HASH JOIN | | 1320 | 44880 | 4118 (2)| 00:00:50 | |* 6 | TABLE ACCESS FULL | SHIPMENTDETAILS | 304 | 6080 | 1070 (2)| 00:00:13 | | 7 | TABLE ACCESS FULL | ITEM | 3588K| 47M| 3036 (1)| 00:00:37 | |* 8 | TABLE ACCESS FULL | ORDERS | 54903 | 965K| 663 (3)| 00:00:08 | |* 9 | TABLE ACCESS BY INDEX ROWID| CUSTOMER | 1 | 33 | 1 (0)| 00:00:01 | |* 10 | INDEX UNIQUE SCAN | PK_CUSTOMER | 1 | | 0 (0)| 00:00:01 | |* 11 | INDEX UNIQUE SCAN | PK_PRODUCT | 1 | | 0 (0)| 00:00:01 | | 12 | TABLE ACCESS BY INDEX ROWID | PRODUCT | 1 | 109 | 1 (0)| 00:00:01 | -------------------------------------------------------------------------------------------------- Predicate Information (identified by operation id): --------------------------------------------------- 4 - access("I"."ORDERID"="O"."ORDERID") 5 - access("SD"."SHIPMENTID"="I"."SHIPMENTID") 6 - filter("SD"."SHIPSTATUS"<>'C') 8 - filter("O"."ORDERDATE">=SYSDATE@!-30) 9 - filter("C"."LASTNAME" LIKE 'SMI%') 10 - access("C"."CUSTOMERID"="O"."CUSTOMERID") 11 - access("P"."PRODUCTID"="I"."PRODUCTID") Execution Plan
  • 26. 2/21/2013 Confidential - Internal Use Only 26 SELECT COUNT(1) FROM Customer WHERE LastName LIKE 'SMI%' 1917 / 52189 = .04 SELECT COUNT(1) FROM Orders WHERE OrderDate >= SYSDATE - 30 55067 / 690671 = .08 SELECT COUNT(1) FROM Orders WHERE OrderStatus <> 'C' 3760 / 690671 = .005 o .08 .04i c psd a .005 SQL Diagram
  • 27. 2/21/2013 Confidential - Internal Use Only 27 • Only 0.5% of rows are <> ‘C’ • How about changing the query? – AND o.OrderStatus = 'I' • Add an Index on OrderStatus – Collect histograms SELECT OrderStatus, COUNT(1) FROM Orders GROUP BY OrderStatus I 3760 C 686911 Data Skew Problems
  • 28. 2/21/2013 Confidential - Internal Use Only 28 New Execution Plan CREATE INDEX order_status ON Orders (OrderStatus) Execution Stats – 7,221 Logical Reads ----------------------------------------------------------------------------------------------------- | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | ----------------------------------------------------------------------------------------------------- | 0 | SELECT STATEMENT | | 1581 | 301K| 3722 (1)| 00:00:45 | |* 1 | HASH JOIN | | 1581 | 301K| 3722 (1)| 00:00:45 | |* 2 | HASH JOIN | | 1581 | 270K| 2655 (1)| 00:00:32 | | 3 | NESTED LOOPS | | | | | | | 4 | NESTED LOOPS | | 1581 | 101K| 2587 (1)| 00:00:32 | |* 5 | HASH JOIN | | 303 | 15756 | 170 (1)| 00:00:03 | |* 6 | TABLE ACCESS BY INDEX ROWID| ORDERS | 303 | 5757 | 33 (0)| 00:00:01 | |* 7 | INDEX RANGE SCAN | ORDER_STATUS | 3811 | | 9 (0)| 00:00:01 | |* 8 | VIEW | index$_join$_001 | 2055 | 67815 | 137 (1)| 00:00:02 | |* 9 | HASH JOIN | | | | | | |* 10 | INDEX RANGE SCAN | CUSTOMER_LN | 2055 | 67815 | 14 (8)| 00:00:01 | | 11 | INDEX FAST FULL SCAN | PK_CUSTOMER | 2055 | 67815 | 123 (0)| 00:00:02 | |* 12 | INDEX RANGE SCAN | PK_ORDERINFO | 5 | | 2 (0)| 00:00:01 | | 13 | TABLE ACCESS BY INDEX ROWID | ITEM | 5 | 70 | 8 (0)| 00:00:01 | | 14 | TABLE ACCESS FULL | PRODUCT | 8914 | 948K| 68 (0)| 00:00:01 | | 15 | TABLE ACCESS FULL | SHIPMENTDETAILS | 836K| 15M| 1064 (1)| 00:00:13 | -----------------------------------------------------------------------------------------------------
  • 29. 2/21/2013 Confidential - Internal Use Only 29 • Tuning SQL gives more “bang for the buck” • Make sure you are tuning the correct query • Use Wait Events and Response Time Analysis – Locking problems may not be a Query Tuning issue – Wait events tell you where to start • Use “Real Execution Plans” – Get plan_hash_value from V$SESSION, V$SQL – Pass it to V$SQL_PLAN to get Real Plan • Ignite – Does All of Above For You – OEM Does not Give you Enough Details • SQL Diagramming - “Get it right the First Time” Takeaway Points
  • 30. Q&A Thank you for attending. More questions? Contact Dean at DeanRichards@confio.com Download free trial of Ignite at http//www.confio.com 2/21/2013 30