Scenario 4-1: Looking at 1NF Your boss walks up to you and hands you a USB flash
ID: 3671162 • Letter: S
Question
Scenario 4-1: Looking at 1NF
Your boss walks up to you and hands you a USB flash drive with the following database:
Model
Specs
PC-1000
Dell OptiPC 200XD, 2.0 Ghz, 512mb RAM, 40 GB HD
PC-1250
Dell SlimPC 400LX, 2.25Ghz, 2gb RAM, 160GB HD
PC-1500
Dell OptiPC 300XD 1.5Ghz, 4gb RAM, 200 GN HD
Your boss asks you if anything is wrong with the database and, if so, what should be done with it. How should you respond?
Scenario 4-2: Comparing Clustered and Non-Clustered Indexes
Your boss wants to speed things up on the company’s database server. Therefore, he is thinking of having you create a couple of indexes. He asks you to explain the advantages and disadvantages of creating a clustered index versus a non-clustered index. How should you respond?
Model
Specs
PC-1000
Dell OptiPC 200XD, 2.0 Ghz, 512mb RAM, 40 GB HD
PC-1250
Dell SlimPC 400LX, 2.25Ghz, 2gb RAM, 160GB HD
PC-1500
Dell OptiPC 300XD 1.5Ghz, 4gb RAM, 200 GN HD
Explanation / Answer
A properly working data should Use storage space efficiently, Eliminate redundant data, and eliminate inconsistent data and easily maintenance. If anything is wrong with the database then it may be for duplicated rows in the table or having multi value or Entries in a column are of the same kind. So for overcome these problem we should Eliminating insertion, update and delete anomalies, transitive dependencies and reducing non-key data redundancy.
Your boss wants to speed things up on the company’s database server. Therefore, he is thinking of having you create a couple of indexes then yes having a clustered index does speed up, even inserts and delete but when you pick a good clustered index and picking a right clustering key.
In Clustered Index uses only one clustered index for a table made by primary key and the leaf nodes of a clustered index contain the data pages. The biggest advantage is that it
quickly searches result when records are retrieved by the cluster index that use fields that are a part of the cluster index might use less data space. Along with this it takes time to update records if only when the fields in the clustering index are changed. A clustered index change is made to a value of an indexed column, and need to of re-sorting rows to maintain order is a definite performance hit. But it accesses the row directly that is being stored in the same order. So, the clustered index when en it compared with non-clustered index reading from a clustered index is generally faster than reading from a non-clustered index.
In Non-Clustered Index there are only 249 non-clustered indexes for a table made by the any key and the leaf node does not consist of the data pages. Non-clustered indexes need extra work to follow the pointer to the row to retrieve any other values.
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