Database DataWarehousing (MOSC)

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Blocking session in Parallel executions

edited Sep 16, 2013 10:14PM in Database DataWarehousing (MOSC) 5 commentsAnswered
 The following is the scenario where im seeing blocking session in parallel executions,
sid :535  -- qc session (px Deq Execute reply) or rarely PX Deq Credit: send blkd

sid : 569 -- blocking session (db file sequenetial read).and sometimes latch:cache buffer chains,PX DQ: TABLE Q normal

9k5vg1jb9bb58 -- sql id( attaching the sql monitor report for various executions 13s and 43s,1.1 mins)

in 43s report, when you notice the execution plan  there are additional parallel process being alloted at (PX PARTION LIST ALL,MAT_VIEW Access by local index rowid)

the query causes contention among session with waits on PX DEQ: Execute reply,the execution plan looks too vague that it looks like nothing can be altered there..at times the query executes much faster(eg: 13s)..

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