About
This initialization parameter is to guarantee a minimal DOP in a adaptive mode to a parallel query.
This parameter controls the minimal percentage of parallel server processes that must be available to start the operation; it defaults to 0, meaning that Oracle will always execute the statement, irrespective of the number of available parallel server processes.
Articles Related
Example
If you want to ensure to get at least 50% of the requested parallel server processes for a statement:
SQL> alter session set parallel_min_percent=50 ;
SQL> select /*+ parallel(s,128) */ count(*)
from sales s ;
select /*+ parallel(s,128) */ count(*) from sales s
*
ERROR at line 1:
ORA-12827: insufficient parallel query slaves
available
If there are insufficient parallel query servers available – in this example less than 64 parallel servers for a simple SQL statement (or less than 128 slaves for a more complex operation, involving producers and consumers) - you will see ORA-12827 and the statement will not execute. You can capture this error in your code and retry later.