When is setting OPTIMIZER_INDEX_COST_ADJ appropriate?

The initialization parameter OPTIMIZER_INDEX_COST_ADJ has a certain popularity in the area of Oracle Database Performance Tuning. Especially, it can be used to make the Optimizer favor index access instead of full table scans. But that is not necessarily appropriate – in fact it can have very counterproductive effects on performance. Richard Foote has some very instructive postings about this, especially this one is impressive, in my view.

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