ctx_ddl.sync_index('CNDYBK.CIDX_IMAGE_TITLE' , '50M');
There is no benefit to having cost-based-optimization of those queries because the rule-based query plan is ALWAYS optimal. The Cost Based Optimizer can only slow them down. As for the Text (Domain) index, in our example the BOOKS_INDEX index. A context index that has been ANALYZED will participate in cost-based optimization. A context index that has not been ANALYZED cannot provide selectivity and cost estimates, so it will do rule-based optimization. Thus, ANALYZING the domain index can change the behavior and performance of the context index. Whether or not it is "required" is up to your application.
So: ANALYZE the domain index if you want to. Do NOT ANALYZE the underlying DR$ tables respective DR# tables.
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