Oracle 12c Advanced Compression and ADO/ILM (Heatmap)

[peter_strauss]

Hello,

We've experienced very good results with Oracle compression in 11g. Oracle 12c introduces two methods for compression of data: Advanced compression (Note 2138262), and ADO/ILM (Note 2441683).

So far for our production systems we have only enabled ADO/ILM.

I was wondering if anyone has had experience enabling both Advanced Data Compression and ADO/ILM at the same time, and whether this is recommended or not.

Kind regards,

Peter

[peter_strauss]

Hello Janos,

In the end the issue on the customer's system was resolved with the following note:

2773463 - Bad performance due to high number of entries in ILM_RESULT$ get not purged

Now HEAT_MAP is enabled and there is no adverse impact on system performance.

Kind regards,

Peter

[peter_strauss]

Hello Janos,

Is there any documentation available to support your recommendation?

Kind regards,

Peter

[janos_mucsi-besze]

Hi Peter,

We do not recommend to use Advanced Compression combined with ADO/ILM as it will result in weird issues, like exponentially growing tables. Which is exactly the opposite we want to have with compression in general.

Either use Advanced Compression or ADO/ILM.