hi @alamb , i think there is some issue while running it locally from docker image , just raising a PR , I think it pretty nice , if you think any modification needed please let me know

Thank you so much @Adez017 -- this is looking great

Given the title of this post is about user defined window functions, there is not very much discussion about that topic -- most of the content is about window functions in general

Perhaps you can structure the post so that it

1. Introduces window functions in general and what they do (you have most of this content already)
2. Walks through an example of creating a user defined window functions in a bit more detail (I think you can borrow / copy liberally from https://datafusion.apache.org/library-user-guide/adding-udfs.html#registering-a-window-udf)

What do you think?

And thanks again for starting this post

I had done a bunch of updates regarding your advice . i need you to review it again and give the feedback . Thank you very much for the efforts

last night i was working on tihs and got that without your supervision and guidance I cant able to finish . i am not able to get the enough data to justify how datafusion outperforms other engines in query performances and I think I need your help.
@alamb @Dandandan

Thanks @Adez017 -- I very much have this on my list of things to review. I expect to do so later this afternoon

Thanks @Adez017 -- I very much have this on my list of things to review. I expect to do so later this afternoon

Great to hear @alamb . i am no sure about the Performance Gains section . we can have to have a closer look on that

Thank you very much @Adez017

I took another pass through this post and did

1. some small wordsmithing and formatting tweaks.
2. Added a section on how window functions are implemented
3. Updated the date

I just pushed the commits directly to your branch to hopefully reduce the back and forth

I think this blog is now ready to publish, but it would be great if you had a chance to review it again. I will also send a note to the mailing list and slack/discord,

Hi @alamb i would love to do so , get back to you soon as i finish reviewing it

hi @alamb , i had done some changes about spells , etc . i think it is ready to be merged . i would prefer please look at the post one final time before merging . for me , its looks pretty good and awsome , upto the mark .😁

Thanks @Adez017 ! Let's give it another day or two for any remaining comments and then I'll plan to publish it

Sure @alamb 👍

Thanks @Adez017 ! Let's give it another day or two for any remaining comments and then I'll plan to publish it

I think now , we should move forward @alamb

Thanks again @Adez017 @Dandandan @getChan and @comphead

The blog is now live: https://datafusion.apache.org/blog/2025/04/19/user-defined-window-functions/