Do not write ColumnIndex for null columns when not writing page statistics

[etseidl]

Which issue does this PR close?

Closes #6010.

Rationale for this change

The ColumnIndex for an all-nulls column will be written even when page statistics are disabled. This is not the case for columns that have non-null values.

What changes are included in this PR?

This PR calls to_invalid() on the constructed ColumnIndexBuilder when page statistics are not requested (statistics_enabled != EnabledStatistics::Page). This allows for not writing the null-column statistics in update_column_offset_index().

arrow-rs/parquet/src/column/writer/mod.rs

Lines 643 to 650 in bed3746

	if null_page && self.column_index_builder.valid() {
	self.column_index_builder.append(
	null_page,
	vec![0; 1],
	vec![0; 1],
	self.page_metrics.num_page_nulls as i64,
	);
	} else if self.column_index_builder.valid() {

.

Are there any user-facing changes?

No

[alamb]

Thanks @etseidl - I will check this one out shortly

[alamb]

Thank you for this contribution @etseidl. I reviewed the code and logic carefully

I took the liberty of merging this PR up from main so the CI would pass.

[alamb]

I think the reason this works currently for columns without null is that the ColumnIndex builder is marked as invalid if there are no page statistics at the end of the page. However, when the column has no data this code is not run

arrow-rs/parquet/src/column/writer/mod.rs

Line 661 in 9b34950

self.column_index_builder.to_invalid();

So TLDR is I think this change looks good to me

[alamb]

I verified that this test covers the code by removing the change and verifying the test fails like

assertion failed: column_close_result.column_index.is_none()
thread 'column::writer::tests::test_no_column_index_when_stats_disabled' panicked at parquet/src/column/writer/mod.rs:3044:9:
assertion failed: column_close_result.column_index.is_none()
stack backtrace:
   0: rust_begin_unwind
             at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/std/src/panicking.rs:652:5
   1: core::panicking::panic_fmt
             at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/core/src/panicking.rs:72:14
   2: core::panicking::panic
             at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/core/src/panicking.rs:146:5
   3: parquet::column::writer::tests::test_no_column_index_when_stats_disabled
             at ./src/column/writer/mod.rs:3044:9
   4: parquet::column::writer::tests::test_no_column_index_when_stats_disabled::{{closure}}
             at ./src/column/writer/mod.rs:3024:50
   5: core::ops::function::FnOnce::call_once
             at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/core/src/ops/function.rs:250:5
   6: core::ops::function::FnOnce::call_once
             at /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/core/src/ops/function.rs:250:5
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

[alamb]

I double checked and I believe this PR contains no breaking API changes so merging it directly to main (for inclusion in 52.0.0)

[alamb]

Thanks again @etseidl