Download Database Tuning in Oracle

Database Tuning in
- Philip K. Kuruvilla
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Database Tuning in
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The World Wide Wait
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Looks Familiar ?
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Agenda
• Why tune databases
• Scope for tuning
• Parameters
• Design
• Monitor and Analyze
• Trivia
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Why is it so critical?
Web Server
Database
The Database lies at the root of an e-commerce application !
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Scope for Tuning
• System level
• Operating System, Hardware
• Database level
• Temporary space, Rollback segments
• Application level
• Query Tuning, Design
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Tuning Parameters
• Throughput and Response Time
• Throughput: Ratio of total data read to
total time spent in servicing the request
• Response Time: Difference between
time at which a request is completed
and response is received
• Type of Application
• OLTP (requires better throughput)
• Batch processing (requires shorter
response time)
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Design
• Normalization
• Not always a good idea to Normalize
• Better to have a single table here
Banner ID
Course
Banner ID
Professor
B0000001
ECMM6000
B0000001
G. Sullivan
B0000002
ECMM6010
B0000002
T. Trappenberg
B0000003
ECMM6020
B0000003
S. Marche
B0000004
ECMM6030
B0000004
A. Uteck
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Application Design
• Simple and efficient queries
• Minimise the number of query blocks
SELECT *
FROM ALL_STUDENTS A
WHERE A.NAME IN
(SELECT GS.NAME
FROM GRAD_STUDENTS GS)
=
SELECT *
FROM ALL_STUDENTS A,
GRAD_STUDENTS GS
WHERE A.NAME = GS.NAME
• Return efficient batch sizes
• Use Stored Procedures/ Functions/ Triggers
•Startup costs are high. Running costs are low
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•
•
•
•
•
Indexes
What are they?
• Defined on a column
• Avoid full table scans
How do they work
When do they NOT work !
Trade off between insert/update
and select
Primary keys are automatically
indexed
Banner ID
Row ID
B001
1
B002
6
B003
3
B005
2
B008
5
B010
4
rowID
(hidden
)
Banner
ID
Name
Age
Tel
1
B001
Chris
20
23232
2
B005
Bates
21
23232
3
B003
Hugh
29
23902
4
B010
Mark
28
23902
5
B008
Martin
33
23920
6
B002
Jones
22
32902
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Monitoring
• Plan table
• Shows how an SQL query is executed
• Shows use of indexes, effect of
Optimizers
• Gives a “cost factor” for a query
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Explain Plan table
PRODUCT_OR
DER
CUSTOMER
ORDER_DETA
IL
CUST_ID
ORDER_ID
ORDER_ID
FNAME
CUST_ID
PRODUCT ID
LNAME
TOTAL
QTY
SELECT POD.PROD_ID,
POD.QTY
FROM CUSTOMER C,
PRODUCT_ORDER PO,
PRODUCT_ORDER_DETAIL POD
WHERE C.CUST_ID = 2
AND PO.CUST_ID = C.CUST_ID
AND PO.ORDER_ID = POD.ORDER_ID
SELECT POD.PROD_ID,
POD.QTY
FROM CUSTOMER C,
PRODUCT_ORDER PO,
PRODUCT_ORDER_DETAIL POD
WHERE PO.CUST_ID = 2
Indexed Column
Non Indexed Column
SELECT POD.PROD_ID,
POD.QTY
FROM PRODUCT_ORDER PO,
ORDER_DETAIL POD
WHERE PO.CUST_ID = 2
AND PO.ORDER_ID = POD.ORDER_ID
AND PO.CUST_ID = C.CUST_ID
AND PO.ORDER_ID = POD.ORDER_ID
SELECT STATEMENT Optimizer=CHOOSE (Cost=3 Card=1
Bytes=51)
NESTED LOOPS (Cost=3 Card=1 Bytes=51)
NESTED LOOPS (Cost=2 Card=1 Bytes=39)
INDEX (UNIQUE SCAN) OF SYS_C003983 (UNIQUE)
SELECT STATEMENT Optimizer=CHOOSE (Cost=3 Card=1
Bytes=38)
NESTED LOOPS (Cost=3 Card=1 Bytes=38)
NESTED LOOPS (Cost=2 Card=1 Bytes=26)
INDEX (UNIQUE SCAN) OF SYS_C003983 (UNIQUE)
TABLE ACCESS (FULL) OF PRODUCT_ORDER (Cost=1
Card=1 Bytes=13)
TABLE ACCESS (FULL) OF PRODUCT_ORDER (Cost=1
Card=1 Bytes=13)
TABLE ACCESS (FULL) OF PRODUCT_ORDER_DETAIL
(Cost=1 Card=7 Bytes=84)
TABLE ACCESS (FULL) OF PRODUCT_ORDER_DETAIL
(Cost=1 Card=7 Bytes=84)
SELECT STATEMENT Optimizer=CHOOSE (Cost=2
Card=1 Bytes=25)
NESTED LOOPS (Cost=2 Card=1 Bytes=25)
TABLE ACCESS (FULL) OF PRODUCT_ORDER (
Cost=1 Card=1 Bytes=13)
TABLE ACCESS (FULL) OF PRODUCT_ORDER_DETA
(Cost=1 Card=7 Bytes=84)
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Advanced
• Trace functionality
• Real time data
• Can identify deadlocks, excessive waits
• Optimizers within Oracle
• Rule Based Optimizer (RBO)
• Uses Pre–determined rules
• Independent of data
• Cost Based Optimizer (CBO)
• Optimizes based on table/ index information
gathered
• Requires that database is analyzed frequently
• Default in Oracle
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Summary
• Tuning is a series of trade offs
• Always better to tune during the
design phase than after
implementation
• Sometimes it’s plain common sense !
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Trivia
• Oracle has been the leading database
manufacturer for the last 5 years. (source: IDC,
2003)
• Oracle: 39.4%, DB2: 33.6%, SQL Server: 11.1%
• Broad coverage of OS (Windows, Unix & Linux)
• “Unbreakable Campaign”
• Advertising campaign in Late 2001. Declared that
Oracle 9i was “unbreakable”
• Open challenge to hackers
• Windows “Long Horn”. Will feature a new File
system “WinFS” which will store files using
“database technologies” (source: Microsoft)
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References
• Metalink – http://metalink.oracle.com
• Oracle Performance Tuning - Richard J.Niemiec, - Oracle
Press
• Database Design Fundamentals – Naphtali Rishe,1988 –
Prentice Hall
• “Oracle Market share”
http://www.oracle.com/ip/index.html?database1.html
• “Unbreakable system”
http://www.oracle.com/oramag/oracle/02mar/index.html?o22break.html
• “Microsoft LongHorn”
http://msdn.microsoft.com/Longhorn/understand
ing/pillars/WinFS/default.aspx
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