Lecture03 Monitoring and Tuning the Operational System Ch19

8/12/2019 Lecture03 Monitoring and Tuning the Operational System Ch19

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Chapter 19

Methodology Monitoring and

Tuning the Operational System

Pearson Education 2009


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Chapter 19 - Objectives

Meaning of denormalization.

When to denormalize to improve performance.

Importance of monitoring and tuning the

operational system.

How to measure efficiency.

How system resources affect performance.



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Step 7 Consider the Introduction of

Controlled Redundancy

To determine whether introducing redundancy in

a controlled manner by relaxing normalization

rules will improve the performance of the system.



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Result of normalization is a design that is

structurally consistent with minimal redundancy.

However, sometimes a normalized database does

not provide maximum processing efficiency.May be necessary to accept loss of some benefits

of a fully normalized design in favor of

performance.



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Also consider that denormalization:

makes implementation more complex;

often sacrifices flexibility;

may speed up retrievals but it slows down

updates.



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Consider denormalization in following

situations, specifically to speed up frequent or

critical transactions:

Step 7.1 Combining 1:1 relationships

Step 7.2 Duplicating non-key attributes in

1:* relationships to reduce joins

Step 7.3 Duplicating foreign key attributesin 1:* relationships to reduce joins


Hoi cac buoc loai bo du thua


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Step 7.4 Duplicating attributes in *:*

relationships to reduce joins

Step 7.5 Introducing repeating groups

Step 7.6 Creating extract tables

Step 7.7 Partitioning relations.



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Sample Relation Diagram



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Sample Relations



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Step 7.1 Combining 1:1 relationships



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Step 7.2 Duplicating non-key attributes in 1:*




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1:* relationships: Lookup Table



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1:* relationships: Lookup Table



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Step 7.3 Duplicating FK attributes in 1:*

relationship to reduce joins



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Step 7.4 Duplicating attributes in *:*




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Step 7.5 Introducing repeating groups



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Step 7.6 Creating extract tables

Reports can access derived data and perform multi-

relation joins on same set of base relations. However,

data the report is based on may be relatively static

or may not have to be current.

Possible to create a single, highly denormalized

extract table based on relations required by reports,

and allow users to access extract table directly

instead of base relations.



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Step 7.7 Partitioning relations

Rather than combining relations together,

alternative approach is to decompose them

into a number of smaller and more

mannageable partitions.Two main types of partitioning: horizontal

and vertical.


Hoi 2 loai phan nho.Dap an horizontal, vertical


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Step 7.7 Partitioning relations


Co hinh nay! Hoi phan nhu nay la horizontal hay vertical


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Advantages and disadvantages of

denormalization



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Step 8 Monitor & Tune Operational System

To monitor operational system and improve

performance of system to correct inappropriate

design decisions or reflect changing requirements.



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Number of factors may be used to measure efficiency:

- Transaction throughput: number of transactions processedin given time interval.

- Response time: elapsed time for completion of a single

transaction.

- Disk storage: amount of disk space required to storedatabase files.

No one factor is always correct. Have to trade each off

against another to achieve reasonable balance.

Need to understand how the various hardwarecomponents interact and affect database performance.



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DreamHome wish to hold pictures of properties,

and comments that describe main features of

property.


Co hinh nay. chon dap an la monitor & Tune

Lecture03 Monitoring and Tuning the Operational System Ch19

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