CX Packet Wait Type

  • What does CX Packet Wait Type mean. When is this wait type is seen the Database performance very low.

    Can any tell me the cause for this wait type and how to handle it.



  • This is the wait for CPU to complete its transcations, see set Parallelism optin on SP_Config for more detail 🙂

  • More specifically, it's a parallelism skew. SQL has paralleled the query and parts of it finished faster than other parts.

    There's a couple options here.

    It could be that the skew has happened because the statistics are outdated and SQL didn't realise how much data it really would have to process. It could be that there are missing indexes and so a query that shouldn't be running parallel is.

    The easiest fix is to reduce the maxdop setting for the server and, if this is an OLTP system that may be a good idea anyway. It's not always the best fix.

    Gail Shaw
    Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
    SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass

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