Thursday 24 March 2016

PX Deq Credit: send blkd wait event in AWR

  • PX Deq Credit: send blkd 

    • The PX Deq Credit: send blkd is an idle event in a parallel execution wait event for RAC. 
    • It may happen that several Object  in schema were defined that "degree of parallelism’ different from 1.
    • Use of Oracle parallel queries may cause optimized to choose ‘full table scan’ and ‘hash join’ instead of index access and ‘nested loops join’.
    • So, parallelism is not usually employed in OLTP systems. You can alter all those objects with NOPARALLEL option.

    You can check it in any DB with the following queries:
    SELECT TABLE_NAME FROM USER_TABLES WHERE TRIM(DEGREE) <> '1' ORDER BY 1;
    SELECT INDEX_NAME FROM USER_INDEXES WHERE TRIM(DEGREE) <> '1' ORDER BY 1;

No comments:

Post a Comment