How SQL statements Works in oracle
Connect the instance using User process and server process Once Basic validation completed SQL statement ready to execute Syntax Check Semantics check Shared pool check Syntax Check: The database validates the sql query syntax is correct or not. Example: SQL> select from dba_objects; select from dba_objects * ERROR at line 1: ORA-00936: missing expression SQL> Semantics check Oracle Verify all column and table names using the dictionary, and confirm that you have permission to see the data. Shared pool Check Once syntax and semantics check done the server processer will initiate the sql query. Server process will check the library cache In the Library cache server process will check Most recently user to the least recently used algorithm for match the sql statement. If library cache matches the sql statements that’s called soft parsing If there is no match, the server process must continue with the creation of the execution plan hard p