Function prepare_selection_for_page_skipping 

fn prepare_selection_for_page_skipping(
    plan_builder: ReadPlanBuilder,
    projection_mask: &ProjectionMask,
    offset_index: Option<&[OffsetIndexMetaData]>,
    total_rows: usize,
) -> ReadPlanBuilder

Prepare row selection execution when page pruning produced sparse column data.

Some pages can be skipped during row-group construction if they are not read by the selections. This means that the data pages for those rows are never loaded and definition/repetition levels are never read. When using RowSelections selection works because skip_records() handles this case and skips the page accordingly.

However, with the current mask design, all values covered by a mask chunk are decoded before the mask filter is applied. Thus a chunk cannot cross a page that was skipped during row-group construction.

A simple example:

• the page size is 2, the mask is 100001, row selection should be read(1) skip(4) read(1)
• the ColumnChunkData would be page1(10), page2(skipped), page3(01)

Mask execution records the row ranges loaded for every projected column, so each mask chunk stays within loaded data and skip_records() crosses the gaps. This applies both to an explicit mask policy and to Auto when it resolves to mask execution.