Redundant index

Help Query Tuning
1

Hello,
We are currently copying data from DB2 to MemSQL and data architect is creating tables in MemSQL according to the requirement. While looking into the table definitions, I noticed the following. on the table.

PRIMARY KEY ( a, b ),
KEY (a),
KEY (b);

My question is doesn’t the KEY(a) looks redundant here, as PK already has the
same leading column?

Thanks.

2

Yes that’s right, KEY(a) is redundant. We have considered erroring in this case to make it clearer the key is redundant, but right now do what MySQL does and allow the CREATE to run.

-Adam