Primary vs secondary indexes in DBMS Theory - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to identify the type of index that uniquely identifies each record in a database table.

DBMS Theory

The index that uniquely identifies each record is called a [1] index.

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Aclustered

Bsecondary

Cforeign

Dprimary

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing primary index with secondary index.

Thinking foreign key is an index type.

A primary index uniquely identifies each record in a database table. It ensures that no two rows have the same key value.

2fill in blank

medium

Complete the sentence to describe the index used to improve query performance on non-primary key columns.

DBMS Theory

An index created on columns other than the primary key to speed up queries is called a [1] index.

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Aprimary

Bsecondary

Cunique

Dclustered

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing secondary index with primary index.

Assuming secondary index enforces uniqueness.

A secondary index is created on columns other than the primary key to improve query speed. It does not guarantee uniqueness.

3fill in blank

hard

Fix the error in the statement about primary indexes.

DBMS Theory

A primary index [1] allow duplicate key values.

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Acannot

Bshould

Ccan

Dmay

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing 'can' or 'may' which imply duplicates are allowed.

Confusing primary index rules with secondary index rules.

A primary index cannot allow duplicate key values because it uniquely identifies each record.

4fill in blank

hard

Fill both blanks to complete the description of secondary indexes.

DBMS Theory

Secondary indexes [1] the primary index and [2] the uniqueness enforced by the primary index.

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Aare separate from

Bare the same as

Cdo not affect

Dalways replace

Attempts:

3 left

💡 Hint

Common Mistakes

Thinking secondary indexes replace the primary index.

Assuming secondary indexes enforce uniqueness.

Secondary indexes are separate from the primary index and do not affect the uniqueness enforced by the primary index. They help improve query speed on columns other than the primary key.

5fill in blank

hard

Fill all three blanks to complete the dictionary that creates a mapping of index types to their main characteristics.

DBMS Theory

index_info = { [1]: '[2]', '[3]': 'Improves query speed on non-key columns'}

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A'Primary Index'

BPrimary Index

CSecondary Index

DUniqueness enforced

Attempts:

3 left

💡 Hint

Common Mistakes

Not using curly braces for dictionary.

Mixing up keys and values.

Forgetting quotes around string keys.

The dictionary index_info maps Primary Index to 'Uniqueness enforced' and Secondary Index to 'Improves query speed on non-key columns'.