Improve performance of Row API by storing TypePtr instead of String

[sadikovi]

This PR updates Row struct to store Vec<(TypePtr, Field)> instead of Vec<(String, Field)>. This improves time when reading Parquet files.

For this I had to change record reader to pass type pointer instead of field name. This unfortunately makes it difficult to test, so I added a macro to generate dummy type with a field name.

Benchmark results:

Before

test record_reader_10k_collect             ... bench:  41,689,686 ns/iter (+/- 33,883,503) = 16 MB/s
test record_reader_stock_simulated_collect ... bench: 335,444,189 ns/iter (+/- 36,688,424) = 3 MB/s
test record_reader_stock_simulated_column  ... bench:  14,664,590 ns/iter (+/- 1,444,286) = 87 MB/s

After

test record_reader_10k_collect             ... bench:  26,658,590 ns/iter (+/- 1,773,580) = 25 MB/s
test record_reader_stock_simulated_collect ... bench: 140,238,171 ns/iter (+/- 6,796,855) = 9 MB/s
test record_reader_stock_simulated_column  ... bench:  15,275,906 ns/iter (+/- 349,117) = 84 MB/s

[sadikovi]

Equality is only used in tests, normally user would not run that in the production code.

[sadikovi]

I think we should refactor our tests, there is a lot of code duplication here and there.

[sadikovi]

Fails to run $ rustup component add rustfmt-preview, I tried triggering build over the weekend and today - still the same error.

[sunchao]

Yes, there are some issue in the rustup toolchain right now. See the reddit thread. Let me see if we can use a nightly on a particular date to fix this issue.

[coveralls]

Pull Request Test Coverage Report for Build 706

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 99 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.007%) to 95.776%

---

Files with Coverage Reduction	New Missed Lines	%
record/api.rs	27	96.4%
record/reader.rs	72	87.4%

Totals
Change from base Build 705:	-0.007%
Covered Lines:	13175
Relevant Lines:	13756

---

💛 - Coveralls

[sunchao]

Sorry @sadikovi I forgot about this PR. Since parquet-rs has merged into Apache Arrow, could you file a JIRA and submit a PR for that? Thanks.

[sadikovi]

Yes, no problem. I think it would be good to mark this repo as moved or something similar.

[sunchao]

Yes. Will update the README for the merge.