Boost Search Efficiency with an Expression-Based Index

Creating an Expression Index in PostgreSQL

Write a PostgreSQL query to create an index on an expression to optimize function-based queries.

Solution:

-- Specify the action to create an index.
CREATE INDEX idx_users_lower_username 
-- Define the target table and a function-based expression for the index.
ON Users(LOWER(username));

Explanation:

• Purpose of the Query:
• To optimize queries that perform case-insensitive searches on the username column.
• Key Components:
• LOWER(username) : The expression used to compute index values.
• idx_users_lower_username and ON Users(...) : Define the index name and target table.

Notes:

• Expression indexes are valuable when queries consistently use functions on indexed columns.
• This index helps avoid full table scans for case-insensitive comparisons.

For more Practice: Solve these Related Problems:

• Write a PostgreSQL query to create an expression index on the lower-case version of the "username" column in the "Users" table.
• Write a PostgreSQL query to create an expression index on the date part of the "created_at" column in the "Orders" table.
• Write a PostgreSQL query to create an expression index on the upper-case version of the "email" column in the "Contacts" table.
• Write a PostgreSQL query to create an expression index on the calculated column (price * quantity) in the "Sales" table.

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