Flow Of Statement Processing?

SQL Statement Processing Steps:
1. Create a cursor.
2. Parse the statement.

parsing (syntax check, semantic check, privilege check, allocate private sql area, shared pool check (library cache check shared sql area. Here is hard or soft parse)SQL queries submitted to the system first run through the parser, which checks syntax and analyzes semantics. The result of this phase is called a parsed representation of the statement.

This parsed representation is then sent to the optimizer, which handles three main functionality:Transformation, estimation, and execution plan generation.

3. Describe query results.
4. Define query output.
5. Bind variables.
6. Parallelize the statement.
7. Execute the statement.
8. Fetch rows of a query.
9. Close the cursor.

- What stages from the above are included in the 'Query Optimizer Stage'
- Is the parse tree created after doing both syntax check and systematic check as I found notes where they mention it was done before symantic check
- What stages are skipped when doing soft parse vs hard parse
-when mentioned parsed representation, is that the same as parse tree.

I am just trying to understand more the flow of the query processing.