MySQL Forums :: Performance :: HELP! making choises on Performance - Storage engine - Caching

Several queries per second - yawn. Several per millisecond - that would be a challenge. So, probably don't need any caching.

MyISAM vs InnoDB -- You possibly want the security of InnoDB. If the master crashes, it can recover virtually everything, and do it more automatically than MyISAM. Changing a table to InnoDB:
ALTER TABLE foo ENGINE=InnoDB;
It will take time proportional to the size: hours if the table is gigabytes.

Any tables that don't have a PRIMARY KEY -- you should add one as you do the alter:
[/code]
ALTER TABLE foo
ADD COLUMN id INT UNSIGNED AUTO_INCREMENT NOT NULL,
PRIMARY KEY (id),
ENGINE=InnoDB;
[/code]
(Do them all in one step.)
If you already have a PRIMARY KEY, you don't need to change it.

User identifiable info being stored? Credit cards being stored? These are security issues that you should either avoid or solve before opening the doors.

Number of databases, number of tables -- do what is 'right' for the data.