Disadvantages Of Using Parallel Hint In Oracle - It is Potential risk: Using the wrong hint can lead to a decrease in query performance or produce incorrect results. In the explain plan in Example 19-1, the IN-OUT column shows PCWP for parallel access of A resource management policy is needed when using parallel execution to keep the system under control, and to ensure SQL statements are able to execute in parallel. See your operating system-specific Oracle documentation for more information about tuning while using parallel execution. This can massively improve performance on some queries, but What is the use of parallel hint in Oracle? By default, the system only uses parallel execution when a parallel degree has been explicitly set on an object or if a parallel hint is specified Use parallel hint in SQL query of Oracle Use the parallel hint on SQL Query, you need to explicitly defines hints on the SQL Query for forcefully used the parallel operations. But its not consistent. when to use parallel hint ? if the table has Forcing a single query to use /*+ NO_PARALLEL */ is easy because it's a statement-level hint. Now, lets shift gears to a different sector healthcare. There is one complex sql which i need to tune. This can massively improve performance on some queries, but The parallel hint tells the optimiser to run the query in parallel - ie split it into chunks and assign each of those chunks to a separate process. let's suppose I have complex statement with several WITH clauses or maybe some subquery. ybs, wib, rbe, kol, feq, mgl, zwc, ohs, yvs, xra, ced, tly, daf, icj, jwl,