topic Re: Difference between Select All and removing the filter at all in QlikView

Difference between Select All and removing the filter at all

Fri, 09 Nov 2012 21:05:03 GMT

Hi,

I have a report in which I have like 12-13 million records. One of the filters is Country. I have noticed an interesting behaviour for this filters. If I remove country filter at all, it takes ages to give me the result but, instead of removing this filter if I select all countries it takes much less time. Just curious what could be the reason of that. I think both are the same things. Then why in one case it takes too long and in the other not too long.

Any explanation would be highly appreciated.

Thanks,

Re: Difference between Select All and removing the filter at all

Anonymous — Sat, 10 Nov 2012 07:23:29 GMT

I suspect that there's something funny in the data model.

If you select all countries you're effectively ignoring all rows that are not attached to a specific country so Yes, it could be much faster.

Re: Difference between Select All and removing the filter at all

whiteline — Sat, 10 Nov 2012 19:07:23 GMT

Hi.

It seems that you have many records that have null values for Country field.

So when you select all visible (not null) values from Country listbox you cut off all that nulls and dozens of records.

To investigate the data that have nulls add this line into your script (before you load the tables with Country field):

NullAsValue Country;

Now you should see a blank value in Country listbox and able to select the data you've previously discarded.

Re: Difference between Select All and removing the filter at all

IAMDV — Sun, 11 Nov 2012 00:34:38 GMT

I agree with Whiteline. It could be NULL values but we all are guessing here. It will be great if you can provide the application and we can identify the issue. Also, I would recommend check the Information Density of this field in the Table Viewer. And are you using this field as KEY FIELD? How many distant values do you have in this field?

Again, what do you mean by...

tahirghalib wrote:
I have noticed an interesting behaviour for this filters. If I remove country filter at all, it takes ages to give me the result but, instead of removing this filter if I select all countries it takes much less time. Just curious what could be the reason of that.

When you say If I remove country filter at all... do you mean you are using the ClearAll button or are you referring to previous selection in country and when you are trying to remove this filter then its taking loads of time? How many fields do you have in your model and does it behave the same way if you place this field in blank page and try to remove the selection?

Cheers,