Database indexes in Supabase - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a database index?

A database index is like a shortcut in a book's table of contents. It helps the database find data faster without looking at every row.

beginner

How does an index improve database queries?

An index speeds up queries by letting the database quickly locate the data instead of scanning the whole table.

intermediate

What is a downside of using too many indexes?

Too many indexes slow down data changes like inserts, updates, and deletes because the indexes must be updated too.

beginner

What types of columns are good candidates for indexing?

Columns used often in search conditions or joins, like IDs or foreign keys, are good for indexes.

intermediate

What is a unique index?

A unique index ensures that all values in a column are different, preventing duplicate entries.

What does a database index do?

A Deletes duplicate data

B Encrypts the database

C Speeds up data retrieval

D Backs up data automatically

A database index helps the database find data faster, improving query speed.

Which column is best to index?

A A column used in search queries

B A column with mostly unique values

C A column rarely used in queries

D A column with many NULL values

Columns used often in search queries benefit most from indexing.

What is a risk of having too many indexes?

A Faster queries

B Slower data updates

C More storage space saved

D Automatic data backup

Too many indexes slow down inserts, updates, and deletes because indexes must be updated.

What does a unique index enforce?

A Automatic data replication

B Faster data deletion

C Encrypted data storage

D No duplicate values in a column

A unique index ensures all values in the indexed column are different.

When should you avoid adding an index?

A On columns rarely used in queries

B On columns used in joins

C On primary key columns

D On foreign key columns

Indexing columns rarely used in queries wastes resources and slows data changes.

Explain what a database index is and how it helps with query performance.

Think of a book's table of contents.

Describe the trade-offs of using indexes in a database.

Indexes help reading but can slow writing.