How to create cache group for many to many relationship tables?

914264 Nov 28, 2012 5:38 AM

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Hi, Chris,
On page 4-4 in <<Oracle In-Memory Database Cache User's Guide>> there is a saying,
A child table cannot reference more than one parent table.
If there is a many-to-many relationship table in Oracle and I want to cache it in TT, there is no approach to map that?
Or I have to logically break its references to the two tables to the one of them?
I forget to mention that I have a root table and one of its child tables is a many-to-many relationship table.

1. Re: How to create cache group for many to many relationship tables?

ChrisJenkins Nov 28, 2012 6:38 AM (in response to 914264)

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Yes, that's correct. You cannot exactly model this in TimesTen. You need to omit some of the relationships so that things are defined in TimesTen as a pure parent/child relationship. You may also consider putting the tables into separate cache groups. Of course, there are some consequences to doing this:

1. The 'missing' relationship cannot be enforced by TimesTen. The application must enforce/respect it. If it does not some updates may fail to propagate to Oracle if they violate the relationship in Oracle.

2. If parallel AWT is configured (to improve propagation performance) it will not be used for any tables where there are missing relationships. All updates to those tables will be applied sequentially.

Chris
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2. Re: How to create cache group for many to many relationship tables?

914264 Nov 28, 2012 6:55 AM (in response to ChrisJenkins)

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It seems that I can create an independent cache group for the many-to-many relationship table.
Do you mean that in this case TimesTen will automatically detect those tables where there are miss relationships and propagate all updates about them to oracle sequentially if parallel AWT is configured?
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3. Re: How to create cache group for many to many relationship tables?

ChrisJenkins Nov 29, 2012 11:31 AM (in response to 914264)

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Yes, that's correct.

Chris
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