Trying to understand general pool queue time in MC

Luc_Lecocq

Hello,

 

I a using Vertica 7.1.2.2 with 7.1.2.4 MC.

In the main screen, the "General pool activity" shows that the max queue time sometimes goes up to 1sec.

If I click on the point with 1 sec value, it brings me to the activity screen where I can see details on the queue time for the general pool, which shows ..., 0 sec queue time !!

 

For me, there should not be any query queing here, the queing threshold is at 95GB, and I am not using that much when I monitor the use.

 

So what is the actual value of the queue time ?

 

Chris_S

Hi Luc_Lecocq, 

 

There is a known issue with the view that the MC is using which involves incorrect queue times being observed. This stems from the fact that it is difficult to get the queue duration for running queries. I suspect you will see queue duration ~1s only when you have running queries.

When you click on a point in the chart, the activity page will show queue durations for completed queries, which is more accurate. For now, assume that what you see on the activity page is the actual queue duration. 

 

Thanks,

Chris

Luc_Lecocq

Thanks,

 

BTW, do you know if there is a Vertica table where I can find these information ?

Chris_S

To the queue information that the MC sees, look at v_monitor.resource_acquisitions 

The queue duration would be acquisition_timestamp - queue_timestamp

You can find more information here: https://my.vertica.com/docs/7.1.x/HTML/index.htm#Authoring/SQLReferenceManual/SystemTables/MONITOR/RESOURCE_ACQUISITIONS.htm