phpMyAdmin and MySQL Indexes

I have noticed that indexed fields are combined when creating tables using phpMyAdmin. Is it more efficient to manually create separate index keys for each column that I want indexed?

I would like an SQL query that will add the most optimal index (for performance) for the following table. This will help me to better understand this.

Table: custom_field_data
--------------------------------------
field_id : BIGINT UNSIGNED INDEX      - Field definition.
object_id : BIGINT UNSIGNED INDEX   -   Object that field data applies to
value : TEXT      - Actual field value does not need to be indexed at all.


In phpMyAdmin I have

Indexes:

keyname: field_id
type: BTREE
unique: NO
packed: NO
field:
--> field_id       cardinality=18  collation=A
--> object_id    cardinality=18  collation=A
LVL 13
numberkruncherAsked:
Who is Participating?
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

Beverley PortlockCommented:
I depends on how you intend to use the keys. See http://dev.mysql.com/doc/refman/5.1/en/mysql-indexes.html and search for multiple-column index.
0

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
numberkruncherAuthor Commented:
Thanks, that link was very useful.
0
numberkruncherAuthor Commented:
So presumably, would it be worth having both of the following on a performance critical table? Would it be better to just have two separately indexed fields (without any multi-index)?

keyname: field_id
type: BTREE
unique: NO
packed: NO
field:
--> field_id       cardinality=18  collation=A
--> object_id    cardinality=18  collation=A

keyname: field_object_id
type: BTREE
unique: NO
packed: NO
field:
--> object_id    cardinality=18  collation=A
0
Beverley PortlockCommented:
In this case I would have two separate indexes or I might even consider having them the other way round. What I mean is if you NEVER use field_id without object_id but object_id could be used on its own sometimes then I would use

KEY ( object_id, field_id )

because with object_id as the major key it can be used as if it was a separate index but the two of them together still work. If in doubt I generally split the columns into seperate indexes.
0
numberkruncherAuthor Commented:
Thanks again for your help, it is greatly appreciated!
0
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
MySQL Server

From novice to tech pro — start learning today.