This method is intended for use during development.
This plan contains the same information as is presented by the getPlanTree method. The difference is in the presentation.
An empty string is returned if there is no plan. Plans exist when the prepared statement is a SQL query.
The plan shows the operations used to execute the query when the plan is obtained before the associated query has been executed.
Additionally, the plan shows the number of rows that each operation produced when the plan is obtained after the query has
been executed. This plan can be used to gain insight about the execution of the query.
The following is an example of a plan tree, expressed as a String. It is displayed on multiple lines with '|' characters to
represent the structure.