Solution : https://service.sap.com/sap/support/notes/651060 (SAP Service marketplace login required)
Summary :
Oracle Parallel Execution enables simultaneous execution of database operations which significantly decreases total runtime by utilizing more CPU and I/O resources effectively. Key subtypes include Parallel Query, Parallel DML, Parallel DDL, and Parallel Recovery. Main advantages are reduced operation time and enhanced performance, though it may also lead to system performance issues, such as resource bottlenecks and inefficient CPU utilization when the default degree of parallelism is used. Common issues include excessive usage of shared pool memory and inappropriate default settings for parallelism which may especially affect operations like Parallel DML in combination with Index-Organized Tables or when improperly managed post-DDL operations. Critical settings for managing parallelism include PARALLEL_MAX_SERVER)
Key words :
full table scans index fast full scans access, create index alter index rebuild create table, update delete insert parallel ddl parallel ddl, nested loop joins parallel dml parallel dml, parallel query slaves px subheap memory structure, alter session force parallel ddl parallel <degree>, alter session force parallel query parallel <degree>, alter session force parallel dml parallel <degree>, wrong cbo decisions activated parallel query, rbo support parallel query requires
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