We are going to change the value of the '_optimizer_connect_by_cost_based'=FALSE .
Kindly let me know any issue will create for the above change.
This is a hidden parameter for Oracle, why do you want to change it?
Also see this link if it helps but as per the link those are not supported
Oracle hidden optimizer parameters
More specifically, these parameters are not allowed by Oracle for customers to use, except upon the advice of Oracle support themselves.
Sometimes Oracle support will need to require a change to one of these parameters in order to address a defect or issue; at which point in time, changing it would be an acceptable thing to do.
With regards to what issue it will create, there are a few places in Clarity where the 'connect by' syntax is used, and this is syntax that is required in order for Oracle to create hierarchical results of data.
Generally it appears Oracle may advise changing this hidden parameter if a query using 'connect by' starts causing 'Oracle internal errors' (i.e. ORA-600 errors). If you are not having this within Clarity, you probably shouldn't change this parameter. If you are having those with your database, you should be raising a support ticket with Oracle and seeking their recommendations on how to resolve it.
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