04. What is the need for an execution plan?

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What is the need for an execution plan?



Why do databases like MySQL and MongoDB analyze multiple execution plans (or run trial plans) instead of just running the query directly with a default/simple plan? Wouldn’t that be faster?

Analyzing plans does take a little extra time initially, but it's usually worth it — because a bad plan can make your query 100x slower or even never finish on large datasets.

Think of it like this:

 "Spend a few milliseconds choosing the best route, or risk taking a path that takes 10x longer."

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