Hi, I have some questions about creating an index.
First of all, how can I prove to a customer that creating this index, queries that are executed will be improved?
I mean with only observing execution plan cost ?
I have only sql developer installed. Is there any free tool for better analysis?
Second, Can I estimate somehow the downtime for creating ?
I don't have the data of customer internally.
Third, should I delete existing indexes if the columns exist on the new.
For example, if I have idx1 (column1, column2) and idx2 (column1, column3)
and then create idx3(column_1, column_2, column_3) should I delete the previous ?
I am sorry, but I am newbie
Thanks in advance
PS : db version19.0.0.0