Indexes - SQL

What is the main focus of the lecture on database indexing?

It covers indexing in relational databases and emphasizes the importance and benefits of indexes.

What is an index in a relational database?

A structure used to improve query performance by optimizing data retrieval.

What is the main focus of the lecture on database indexing?

It covers indexing in relational databases and emphasizes the importance and benefits of indexes.

What is an index in a relational database?

A structure used to improve query performance by optimizing data retrieval.

How many columns can be used to create an index?

Usually one, but it can be a combination of 2 or 3 columns.

Why are indexes needed in databases?

To allow faster data retrieval, especially in large tables containing millions of records.

What happens when a table grows without indexing?

Retrieving data becomes slower.

How do indexes affect query speed?

Indexes significantly reduce query execution time on large datasets.

How do indexes work in a database?

They help the database locate specific data without scanning all records.

Who decides how data will be retrieved in a query using indexes?

The query optimizer in the database management system (DBMS).

What is query optimization?

The process where the DBMS determines the most efficient way to execute a query.

What does the DBMS use to optimize query performance?

Different algorithms and paths to retrieve data from multiple tables.

Does the DBMS automatically create indexes?

No, it is up to the database developer or administrator to create indexes when necessary.

Why is monitoring performance important in relation to indexes?

To decide when and where indexes are beneficial for optimizing queries.

How do indexes help in locating data?

They point to specific data locations on a disk or in memory.

What kind of index allows for rapid searching using algorithms?

Primary key indexes, which are sorted.

What is the problem with searching data without an index?

The database must scan the entire dataset, which is inefficient for large tables.

On what can indexes be created?

On specific columns, such as first names, to speed up searches.

What are composite indexes?

Indexes that include multiple columns to optimize more complex queries.

Give an example of a single-column index.

An index on the first_name column for rapid lookup of records with the name "Henry."

How can the DBMS use multiple indexes to improve performance?

It can cross-reference indexes, like first name and phone number, to find data more quickly.

What is the syntax to create an index in SQL?

CREATE INDEX index_name ON table_name(column_name)

What is the purpose of composite indexes?

To improve performance in queries that involve searching across multiple columns.

When are composite indexes most efficient?

When they match the query's search pattern.

Are separate indexes on each column more efficient than composite indexes?

No, composite indexes are more efficient, but separate indexes are still better than no index.

What are unique indexes?

Indexes that ensure no duplicate values exist for the specified columns.

When are unique indexes useful?

In queries involving combinations like last_name and birth_date.

Why is choosing the right indexed columns important?

The efficiency of an index depends on how well it matches the query structure.

What should be considered when creating an index?

Data size, query frequency, and the need for faster retrieval.

What is the primary benefit of using indexes?

To improve database performance, especially for large datasets.

What happens when a query lacks an appropriate index?

The query performance slows down, requiring more time to retrieve data.

What role do algorithms play in indexing?

Algorithms are used to search through indexed data faster.

Can multiple indexes be used in a single query?

Yes, multiple indexes can be cross-referenced to improve query performance.

How do composite indexes benefit complex queries?

They optimize queries that involve multiple search criteria across different columns.

What is the key to optimizing query performance with indexes?

Choosing the right combination of indexed columns based on query needs.

What should developers consider when deciding whether to create an index?

The size of the data, frequency of queries, and the need for faster data retrieval.

Index Maintenance

adding and deleting items and updating item values requires updating the index