Why get 1000 records at startup?（Teradata）

[Anonymous]

Hi.

I'm currently investigating performance.

Power BI created in business acquires data from Teradata.

When I investigated the relationship between the Teradata log and Power BI operations, I found that when the PBIX file was started, a query to get 1000 data was running, and then a query to get all the data was running.

Can anyone please tell me why it behaves like this?

　※Since it is business data, the capture cannot be posted. I'm sorry

Also, does it behave the same in other databases (eg Azure Synapse)?

Thank you for your cooperation.

[v-deddai1-msft · Accepted solution]

Hi @Anonymous ,

There two option that may make sense. 'Enable Load' and 'Include in Report Refresh'.

If we disable the option "Enable Load" for the query, when we apply the change, this query table data will not be loaded to data model. But when we refresh the dataset, there is also a query sent to data source. See: https://radacad.com/performance-tip-for-power-bi-enable-load-sucks-memory-up

When we disable the "Include in Report Refresh" option, data will not update in report view of Power BI Desktop after you click "Refresh" button in Desktop. It does nothing to the power BI Service.

If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.

Best Regards,

Dedmon Dai

[v-deddai1-msft]

Hi @Anonymous ,

It is related to Power Query background refresh in power bi desktop. 

By default, when Power Query imports data, it also caches up to 1000 rows of preview data for each query. Preview data helps to present you with a quick preview of source data, and of transformation results for each step of your queries. It's stored separately on-disk and not inside the Power BI Desktop file.

You can disable it in :

For more details, please refer to https://docs.microsoft.com/en-us/power-bi/guidance/power-query-background-refresh 

If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.

Best Regards,

Dedmon Dai

[Anonymous]

Thank you for answering!
I changed the background update settings and confirmed.
As you pointed out, the TOP1000 acquisition query no longer runs at startup.
However, when I recommend the update, TOP1000 seems to run.
Do you know how to set not to perform TOP1000 at the time of update?
(Personally, I'm wondering if the behavior behind the scenes such as "evaluating ..." or "loading the preview model" is the cause.)

Thank you.