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Multi-Column indexes
Posted by: Michael Preiss ()
Date: October 08, 2011 06:45PM

Hello forum,

this has been bothering me for a while and I just cant seem to get a definitive answer.

Let's assume I have a table like this:
Col_A
Col_B
Col_C
Col_D
INDEX(Col_A,Col_B,Col_C,Col_D)

Now this obviously works great if columns A,B,C,D or A,B,C or A,B OR A are used in the where clause.

But what happens if I have to omit say column C because what I want to achieve would be "give me the rows where A=x, B=y, and D=z, regardless of the value of C".

Do I need a second index like INDEX(Col_A,Col_B,Col_D) or is mysql smart enough to figure it out?

Thanks in advance for your help.

/edit
fixed thread title. oops.



Edited 1 time(s). Last edit at 10/09/2011 10:55AM by Michael Preiss.

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Subject Views Written By Posted
Multi-Column indexes 2528 Michael Preiss 10/08/2011 06:45PM
Re: Multi-Cell indexes 719 Jørgen Løland 10/09/2011 10:56AM
Re: Multi-Cell indexes 857 Michael Preiss 10/09/2011 11:55AM
Re: Multi-Cell indexes 684 Jørgen Løland 10/09/2011 12:10PM
Re: Multi-Cell indexes 692 Michael Preiss 10/09/2011 02:40PM
Re: Multi-Cell indexes 691 Rick James 10/11/2011 09:25PM
Re: Multi-Cell indexes 740 Jørgen Løland 10/12/2011 12:04AM
Re: Multi-Cell indexes 624 Michael Preiss 10/14/2011 10:02PM


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