[Solved] This query runs slower than expected:SELECT * FROM products WHERE price > 1000;You created an index on price but performance did not improve. What is a likely cause? | PostgreSQL

PostgreSQL - Performance Tuning

This query runs slower than expected:
SELECT * FROM products WHERE price > 1000;
You created an index on price but performance did not improve. What is a likely cause?

APostgreSQL does not support indexes on numeric columns

BThe index on price deletes rows causing errors

CThe query syntax is invalid and causes failure

DThe query uses a range condition which may cause PostgreSQL to prefer a sequential scan

Step-by-Step Solution

Solution:

Step 1: Understand index use with range queries
Range conditions like price > 1000 sometimes cause PostgreSQL to choose a sequential scan if many rows match.
Step 2: Recognize planner decision
The planner picks the fastest method; if many rows qualify, scanning whole table can be faster than using index.
Final Answer:
The query uses a range condition which may cause PostgreSQL to prefer a sequential scan -> Option D
Quick Check:
Range queries may prefer sequential scan [OK]

Quick Trick: Range filters may cause sequential scans despite indexes [OK]

Common Mistakes:

Thinking index deletes rows
Assuming query syntax is wrong
Believing numeric indexes are unsupported

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This query runs slower than expected:

Step 1: Understand index use with range queries

Step 2: Recognize planner decision

Final Answer:

Quick Check:

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