Does MySQL use existing indexes when creating new indexes?

Question

I have a large table with millions of records.

Table `price`
------------
id 
product 
site 
value

The table is brand new and there are no indexes.

Then I issued a request to create a new index with the following request:

CREATE INDEX ix_price_site_product_value_id ON price (site, product, value, id);

It took a lot of time, the last time I checked, it worked for 5000+ seconds because of the car.

I am wondering if I am creating another index creation, will it use the existing index in process calculation? If so, in what form?

Then run query 1:

CREATE INDEX ix_price_product_value_id ON price (product, value, id);

Then run query 2:

CREATE INDEX ix_price_value_id ON price (value, id);

Answer 1

MySQL 5.1 InnoDB, InnoDB Plugin 1.0, . .

InnoDB:

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Answer 2

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, (site, product, value, id) ( (product, value, id) (value, id)).

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