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You receive the following error message:
ORA-12827: insufficient parallel query slaves available
Which three parameter settings could you change to avoid this error?
A. Decrease the value of PARALLEL_MIN_PERCENT
B. Increase the value of PARALLEL_MAX_SERVERS
C. Increase the value of PARALLEL_MIN_SERVERS
D. Reduce the value of PARALLEL_MIN_TIME_THRESHOLF
E. Increase the value of PARALLEL_DEGREE_LIMIT
F. Set the PARALLEL_DEGREE_POLICY = AUTO
G. Set the PARALLEL_DEGREE_POLICY = LIMITED
Correct Answer: ABG
Explanation/Reference:
A:ORA-12827:
insufficient parallel query slaves available
Cause:PARALLEL_MIN_PERCENT parameter was specified and fewer than minimum slaves were acquired
Action:either re-execute query with lower PARALLEL_MIN_PERCENT or wait until some running queries are completed, thus freeing up slaves
B:Your query doesn’t run because you’ve told Oracle not to run it unless at least 5% of the parallel execution processes are available for your query.Set PARALLEL_MIN_PERCENT=0 or increase the number of parallel execution processes by increasing the PARALLEL_MAX_SERVERS parameter.
G:PARALLEL_DEGREE_POLICY
PARALLEL_DEGREE_POLICY specifies whether or not automatic degree of Parallelism, statement queuing, and in-memory parallel execution will be enabled.
LIMITED
Enables automatic degree of parallelism for some statements but statement queuing and inmemory
Parallel Execution are disabled. Automatic degree of parallelism is only applied to those statements that access tables or indexes decorated explicitly with the PARALLEL clause. Tables and indexes that have a degree of parallelism specified will use that degree of parallelism.
Note:
PARALLEL_MIN_PERCENT operates in conjunction with PARALLEL_MAX_SERVERS and PARALLEL_MIN_SERVERS. It lets you specify the minimum percentage of parallel execution processes (of the value of PARALLEL_MAX_SERVERS) required for parallel execution. Setting this parameter ensures that parallel operations will not execute sequentially unless adequate resources are available. The default value of 0 means that no minimum percentage of processes has been set.
Consider the following settings:
PARALLEL_MIN_PERCENT = 50
PARALLEL_MIN_SERVERS = 5
PARALLEL_MAX_SERVERS = 10
If 8 of the 10 parallel execution processes are busy, only 2 processes are available. If you then request a query with a degree of parallelism of 8, the minimum 50% will not be met.
You can use this parameter in conjunction with PARALLEL_ADAPTIVE_MULTI_USER. In a multiuser environment, an individual user or application can set PARALLEL_MIN_PERCENT to a minimum value until sufficient resources are available on the system and an acceptable degree of parallelism is returned.
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