Question

I Have 2 Question

1. If my table contain a unique column like this:

DROP TABLE IF EXISTS TestTable;
CREATE TABLE TestTable(
ID INTEGER NOT NULL AUTO_INCREMENT PRIMARY KEY,

GUID VARCHAR(32) UNIQUE NULL);

Do i Need to create an Index for this GUID column.

Note: i have GUID column In Where statement with join tables

My Second Question is the update statement will effect the index table if the updated column(s) not have been indexes?

Answer 1

It depends on which database you are using. Different databases have different ways of indexing.

If you are using InnoDB then the Primary Key and Unique Key is already an index, so you won’t need to. If you create manually yet another index for the GUID column then you will have an extra redundant index on that column which wastes space.