More than one root table ,how to design cache group ?

Question

hi,
each cache group have onle one root table , many child table ,if my relational model is :
A(id number,name ....,primary key id)
B(id number,.....,primary key id)
A_B_rel (aid number,bid number,foreign key aid referenc a (id),
foreign key bid referenc b(id))
my select statement is "select ... from a,b,a_b_rel where ...."，
i want to cache these three table , how should i create cache group ?
my design is three awt , Cache group A for A , Cache Group b for b, Cache group ab to a_b_rel ?
are there other better solution ?

Answer 1

As you have discovered, you cannot put all three of these tables into one cache group. For READONLY cache groups the solution is simple, put two of the tables (say A and A_B) in one cache group and the other table (B) in a different cache group and make sure that both use the same AUTOREFRESH interval.
For your case, using AWT cache groups, the situation is a bit mnore complicated. You must cache the tables as two different cache groups as mentioned above, but you cannot define a foreign key relationship in TimesTen between tables in different cache groups. Hence you will need to add logic to your application to check and enforce the 'missing' foreignb key relationship (B + A_B in this example) to ensure that you do not inadvertently insert data that would violate the FK relationship defined in Oracle. Otherwise you could insert invalid data in TimesTen and this would then fail to propagate to Oracle.
Chris