Hash Index

I am trying to create a Hash Index on one of the columns of my table, but as I click 'Apply Changes', it gets automatically converted to BTREE index. Why?
I also want to know which index has good performance, a HASH index or a BTREE index, for an InnoDB table.
LVL 8
rpkhareAsked:
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.

UmeshMySQL Principle Technical Support EngineerCommented:
Which engine are you using for that table?  is it InnoDB/MyISAM ?

Some storage engines allow you to specify an index type when creating an index. The allowable index type values supported by different storage engines are shown in the following table. Where multiple index types are listed, the first one is the default when no index type specifier is given.

Storage                               Engine Allowable Index Types
MyISAM                                     BTREE, RTREE  
InnoDB                                      BTREE
MEMORY/HEAP                        HASH, BTREE  
NDB                                      HASH, BTREE (see note in text)



For your second query...

http://dev.mysql.com/doc/refman/5.1/en/innodb-adaptive-hash.html
0
rpkhareAuthor Commented:
InnoDB.
0
UmeshMySQL Principle Technical Support EngineerCommented:
InnoDB's default index type is "BTREE"..

InnoDB has a mechanism that monitors index searches made to the indexes defined for a table. If InnoDB notices that queries could benefit from building a hash index, it does so automatically.

Note that the hash index is always built based on an existing B-tree index on the table. InnoDB can build a hash index on a prefix of any length of the key defined for the B-tree, depending on the pattern of searches that InnoDB observes for the B-tree 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
rpkhareAuthor Commented:
Thanks
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.

Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.