PostgreSQL - Indexing Strategies
Given the table products(id INT, name TEXT) with a hash index on id, what will the query SELECT * FROM products WHERE id = 10; most likely use?
Given the table products(id INT, name TEXT) with a hash index on id, what will the query SELECT * FROM products WHERE id = 10; most likely use?
medium📝 query result Q13 of 15
Step-by-Step Solution
Solution:
Step 1: Identify query condition type
The query uses an equality condition on theidcolumn:id = 10.Step 2: Match index type to query
Since there is a hash index onid, PostgreSQL will use a hash index scan to quickly find rows whereidequals 10.Final Answer:
A hash index scan for fast equality lookup -> Option BQuick Check:
Equality query + hash index = hash index scan [OK]
Quick Trick: Equality WHERE uses hash index scan if available. [OK]
Common Mistakes:
- Assuming sequential scan always happens
- Confusing bitmap index with hash index
- Thinking hash index supports range queries
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