Optimize char expression

[ajita-asthana]

Which issue does this PR close?

#16009

Rationale for this change

What changes are included in this PR?

Implemented char.rs function to use GenericStringBuilder based on the chr.rs implementation.

Are these changes tested?

In-progress of implementing a benchmark

Are there any user-facing changes?

No

[ajita-asthana]

Which issue does this PR close?

• Closes [datafusion-spark] Optimize char expression #16009

Rationale for this change

What changes are included in this PR?

Are these changes tested?

Are there any user-facing changes?

[logan-keede]

Hi @ajita-asthana, are you still working on this issue?

consider implementing a benchmark like this first(in a separate PR) to measure the performance of current chr function against the one you have implemented.

You should also mark this as a draft PR till then.

[ajita-asthana]

Hey @logan-keede, I am. Will do the benchmarking.

[ajita-asthana]

Hey @logan-keede I am running into import errors unlinked crate. I tried extern crate module_name and it did not work.
The benchmarks are failing because the rust file is not compiled.
Could you please let me how I can resolve the linking errors.

[logan-keede]

Dependencies in rust needs to be mentioned in Cargo.toml of the crate. Have you done that?

[ajita-asthana]

@logan-keede could you please review this when you have time.

[andygrove]

I do see a small performance improvement with these changes:

char                    time:   [9.9009 µs 9.9636 µs 10.036 µs]
                        change: [-3.3878% -2.8089% -2.2840%] (p = 0.00 < 0.05)
                        Performance has improved.

[andygrove]

LGTM. Thanks @ajita-asthana.