[improvement](vectorized) Improve count distinct performance by using fastunion

[zenoyang]

Proposed changes

Issue Number: close #xxx Improve count distinct performance by using fastunion. Testing our user real data has a 10-40% performance improvement.

Problem summary

Describe your changes.

Checklist(Required)

1. Does it affect the original behavior:
   • [x] Yes
   • [ ] No
   • [ ] I don't know
2. Has unit tests been added:
   • [x] Yes
   • [ ] No
   • [ ] No Need
3. Has document been added or modified:
   • [ ] Yes
   • [ ] No
   • [x] No Need
4. Does it need to update dependencies:
   • [ ] Yes
   • [x] No
5. Are there any changes that cannot be rolled back:
   • [ ] Yes (If Yes, please explain WHY)
   • [x] No

Further comments

If this is a relatively large or complex change, kick off the discussion at [email protected] by explaining why you chose the solution you did and what alternatives you considered, etc...

[yiguolei]

wow

[zhangstar333]

hi, I see this improvement also speed up agg function of bitmap_union, why not add it?

[zhangstar333]

LGTM, it's a great work! , And I could speed up to bitmap union using this way later