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Re: InnoDB B+ tree index - duplicate values
Posted by: Rick James
Date: July 08, 2016 11:45PM

Think of it this way...

A secondary index is a table with the columns of the secondary index plus the columns of the primary key. Those are in a BTree ordered by all those columns.

The PRIMARY KEY and the rest of the columns are what live in the main BTree. It is ordered by the (unique) PRIMARY KEY.

The '+' in B+Tree indicates that leaf blocks are linked together. That way, a range scan does not need to drill down the "tree" again when walking out of one block into the 'next'.

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Re: InnoDB B+ tree index - duplicate values
July 08, 2016 11:45PM

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