What is Cxconsumer wait?

What is Cxconsumer wait?

(Republishing, or using this info in a commercial product/website, is prohibited without permission. Description: The simplest explanation of this wait type is that there are parallel plans running.

What is Cxpacket wait?

The SQL Server CXPACKET wait type is a result of parallel query execution and indicates that a session is waiting for the synchronization of threads involved in the parallel process to complete.

What does MaxDoP 0 mean?

Max Degree of Parallelism
MaxDoP stands for ‘Max Degree of Parallelism. ‘ This translates to the maximum number of logical processors that queries triggering Parallelism can recruit. By default, SQL Server comes with MaxDoP = 0, a 0 for this value means that every processor will be used by parallel queries.

How do I resolve Cxpacket?

Check the indexes and statistics on tables used by the query and make sure they are up to date. Check the Cost Threshold for Parallelism (CTFP) and make sure that the value used is appropriate for your system.

What is tempdb spill?

Queries are spilling out to tempdb. This means that SQL Server has poorly estimated the amount of rows that will be returned from an operator. When the row estimate is wrong, the memory grant will be wrong; SQL Server is going to have to use extra space on disk to do the work.

How do you find the maximum degree of parallelism?

To configure the max degree of parallelism option

1. In Object Explorer, right-click a server and select Properties.
2. Click the Advanced node.
3. In the Max Degree of Parallelism box, select the maximum number of processors to use in parallel plan execution.

What does cxconsumer wait mean in SQL Server?

The actual performance issue is with the producer threads, as the consumer threads are just waiting for the producer threads to give them data. By making the consumer threads register CXCONSUMER waits, the remaining CXPACKET waits from the producer threads should be what indicate a performance problem.

How to fix excessive cxpacket and cxconsumer wait types?

The CXPACKET wait stats were lower which meant that the load was more evenly balanced across more cores than before. Brent recommends the following steps if you are seeing excessive CXPACKET and CXCONSUMER wait statistics: Set the CTFP and MAXDOP per industry best practices and then let those settings bake for a few days.

Why are there so many cxpacket waits in SQL Server?

However, in some cases there may not be many CXPACKET waits but instead a few long CXCONSUMER waits or many thousands of short CXCONSUMER waits. Both of these can indicate skewed parallelism or something like a poor join condition causing producer threads to do lots of work without pushing many rows through to the consumer threads.

How long is cxconsumer session ID 797 running?

Session_id 797 is showing high CXCONSUMER waits, and has been running for 2 hours. I’ll assume that is the problematic session. It has performed almost 57.9 million milliseconds of CPU cycles (967 minutes) in 2h 12mi of “real” time (132 minutes).