Add libcudf example with large strings

[davidwendt]

Description

Creating an example that shows reading large strings columns. This uses the 1 billion row challenge input data and provides three examples of loading this data:

• brc uses the CSV reader to load the input file in one call and aggregates the results using groupby
• brc_chunks uses the CSV reader to load the input file in chunks, aggregates each chunk, and computes the results
• brc_pipeline same as brc_chunks but input chunks are processed in separate threads/streams.

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.

[GregoryKimball]

On GH200, the brc_pipeline example seems to be calling cudaHostRegister on the entire file for each chunk.

And it ends up much slower. I'm looking to see if anything in the data source handling could be changed.

[vuule]

On GH200, the brc_pipeline example seems to be calling cudaHostRegister on the entire file for each chunk.

That unexpected. I'll check the code and update here.

[bdice]

Approving -- only a few small suggestions.

[bdice]

Can we rename this to brc? Or does the project need a unique name?

It's a little confusing to have three unique names for this example:

1. The directory is named 1billion
2. The project is named billion
3. The executable is named brc (and variations thereof)

Let's consolidate these.

[davidwendt]

I agree with renaming the directory and project the same. I want to use something easily readable/discoverable from the perspective of someone looking at the examples folder. My suggestion is to use billion_rows for the directory and project name.
I would like to keep the executable names shorter since they are built in context of the parent directory and would look less cumbersome in my opinion. I'd like to keep the brc variations also because the blog uses those names in charts that would need to be regenerated.

[bdice]

That’s fine! Let’s do that.

[vuule]

Looks good, just a few non-blocking suggestions

[ttnghia]

Nit:

• IMO the folder name 1billion is vague/not clean. Typically I would avoid naming anything starting with a number.
• I'm kind of OCD with formatting. For printing information, I would prefer to see the printed sentences as "First letter of each sentence is capitalized" instead of "everything is in lower-case".

[vuule]

Lovely examples. Expected more complex code, especially for the pipeline.

[karthikeyann]

Looks great

[karthikeyann]

nit: to keep it simple,

Suggested change

	auto const mr_name = std::string("pool");
	auto resource = create_memory_resource(mr_name);
	auto resource = create_memory_resource("pool");

[davidwendt]

/merge