PARQUET-1523: [C++] Vectorize comparator interface

[majetideepak]

No description provided.

[wesm]

This isn't what I was thinking when I wrote PARQUET-1523. I thought the proposal was to remove the scalar virtual calls altogether -- this still has virtual calls on the hot path AFAICT. I would be willing to help with refactoring this further

[majetideepak]

Ok. I will make another pass.

[wesm]

@majetideepak do you have some time to look at this? I can also take a pass on it possibly end of this week or next week

[majetideepak]

@wesm I got side-tracked on fixing the build scripts for Vertica's build environment. I will likely finish that this week. I can only work on this next week. Feel free to take a pass on this if you get time before that.

[majetideepak]

@wesm I will work on this today and get back to you.

[wesm]

Thanks. I'll take a look at the build system improvements

[majetideepak]

@wesm I spent some more time with this but couldn't figure out a solution without virtual functions.
The challenge is that the comparator class depends on both the Physical Type and the SortOrder (SIGNED, UNSIGNED). The TypedRowGroupStatistics class that requires this comparator is only templated on the Physical Type. How can we resolve this at compile-time?

[wesm]

Let me have a look at this with fresh eyes and see what I can come up with.

[wesm]

Making some progress on this. I will try to get a patch up by mid-week if not sooner