add a readme for clickbench intro

[waitingkuo]

Which issue does this PR close?

Closes#2902

Rationale for this change

initial work to add datafusion into https://benchmark.clickhouse.com/

What changes are included in this PR?

Are there any user-facing changes?

[codecov-commenter]

Codecov Report

Merging #3186 (6289054) into master (85f7fc9) will increase coverage by 0.01%.
The diff coverage is n/a.

❗ Current head 6289054 differs from pull request most recent head 7dae4c6. Consider uploading reports for the commit 7dae4c6 to get more accurate results

@@ Coverage Diff @@## master #3186 +/- ##
==========================================
+ Coverage 85.86% 85.87% +0.01% 
==========================================
Files 291 291 Lines 52793 52827 +34 ==========================================
+ Hits 45329 45366 +37 + Misses 7464 7461 -3 

Impacted Files	Coverage Δ
datafusion/optimizer/src/eliminate_filter.rs	100.00% <0.00%> (ø)
datafusion/core/src/physical_plan/hash_utils.rs	40.05% <0.00%> (ø)
datafusion/core/tests/sql/aggregates.rs	99.36% <0.00%> (+<0.01%)	⬆️
datafusion/expr/src/aggregate_function.rs	92.33% <0.00%> (+0.02%)	⬆️
datafusion/common/src/scalar.rs	84.74% <0.00%> (+0.13%)	⬆️
datafusion/physical-expr/src/aggregate/min_max.rs	95.91% <0.00%> (+0.16%)	⬆️
datafusion/expr/src/logical_plan/plan.rs	77.95% <0.00%> (+0.17%)	⬆️

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[alamb]

Thanks @waitingkuo -- rather than add something to the root directory, what would you think about putting this data into https://github.com/apache/arrow-datafusion/tree/master/benchmarks ?

I think it is similar in spirit to https://github.com/apache/arrow-datafusion/tree/master/benchmarks/db-benchmark

[waitingkuo]

@alamb sure i can do it. let me spend sometime checking how db-benchmark works. should i move conbench as well?

[alamb]

@waitingkuo moving conbench would be great

[andygrove]

Suggested change

	your can do
	you can do

[andygrove]

Suggested change

	Each query will be only exeute only once, for each query it'll print the SQL expression first then output the result. (Note that this index begins with 1, the ClickBench begins with 0)
	Each query will be executed only once, for each query it'll print the SQL expression first then output the result. (Note that this index begins with 1, the ClickBench begins with 0)

[andygrove]

I think that we should move this file to benchmarks/clickbench/README.md so that all the benchmarks are in one place.

[andygrove]

Thanks for all of the work on this @waitingkuo. It is great to see results published.

[alamb]

FYI here is another approach to running clickbench in the datafusion repo: #7060

[alamb]

Closing as this PR is over a year old. Please feel free to reopen it / rebase it if you plan to keep working on it