SQL Query Processing steps

SQL Query Processing steps

SQL Query Processing steps:-Below are the SQL Query processing steps

Hard Parse :- If hash value of query is not available in shared SQL Area then process will execute hard parsing

1) SQL Parsing
    a) Syntax Check
    b) Semantic Check
    c) Shared Pool Check
2) Optimization  (Generation of Multiple Execution Plan)
3) Row Source Generation (Generation of Query Plan)
4) Execution

Soft Parse :-If hash value of query is available in shared SQL Area  then process will execute soft parsing

1) SQL Parsing
    a) Syntax Check
    b) Semantic Check
    c) Shared Pool Check
2) Execution

1) Syntax Check:- In this check SQL Parser check the Query syntax.
 

2) Semantic Check:-In this check SQL Parser check that Object and columns existence. Also check the priviledges on those objects
 

3) Shared Pool Check :- In this check SQL Parser check for hash value of query in shared SQL Area
 

4) Optimization :-In this step SQL Parser generate multiple execution plan.
 

5) Row Source Generation :-In this step Row source generator (Software) receive optimal execution plan from optimizer and produce a iterative execution plan which is used to produce result set.           
 

6) Execution :-In this step SQL engine execute each row source of Tree ,produced by Row source generator.