[Solved] Given the partial index:CREATE INDEX idx_active_users ON users (last_login) WHERE active = true;What will be the result of this query?... | PostgreSQL

PostgreSQL - Indexing Strategies

Given the partial index:
CREATE INDEX idx_active_users ON users (last_login) WHERE active = true;
What will be the result of this query?
SELECT * FROM users WHERE active = true AND last_login > '2024-01-01';

AThe query will return no rows because partial indexes exclude all rows

BThe query will ignore the partial index and perform a full table scan

CThe query will cause a syntax error due to the partial index

DThe query will use the partial index and return matching rows quickly

Step-by-Step Solution

Solution:

Step 1: Understand partial index condition
The index covers rows where active = true, indexing last_login.
Step 2: Analyze query filter
The query filters on active = true and last_login > '2024-01-01', matching the index condition.
Final Answer:
The query will use the partial index and return matching rows quickly -> Option D
Quick Check:
Query matches partial index condition = uses index [OK]

Quick Trick: Query filters must match partial index WHERE to use it [OK]

Common Mistakes:

Assuming partial index causes syntax errors
Thinking partial index excludes all rows
Believing query ignores partial index if condition partially matches

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Given the partial index:

Step 1: Understand partial index condition

Step 2: Analyze query filter

Final Answer:

Quick Check:

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