Struct SegmentReader 

pub struct SegmentReader<'a> { /* private fields */ }

Reads and decodes columns from a segment byte buffer.

Supports column projection (only decode requested columns) and block predicate pushdown (skip blocks whose stats prove no match).

Implementations

impl<'a> SegmentReader<'a>

pub fn open(data: &'a [u8]) -> Result<Self, ColumnarError>

Open a plaintext segment from a byte buffer.

Validates the NDBS header and footer CRC. If data starts with SEGC (an encrypted envelope) and kek is None, returns Err(MissingKek). If data starts with NDBS (plaintext) and kek is Some, returns Err(KekRequired) — refusing to load unencrypted data when encryption is configured.

To read an encrypted segment, use OwnedSegmentReader::open_with_kek.

pub fn footer(&self) -> &SegmentFooter

Access the footer metadata.

pub fn row_count(&self) -> u64

Total row count in the segment.

pub fn column_count(&self) -> usize

Number of columns in the segment.

pub fn read_column( &self, col_idx: usize, ) -> Result<DecodedColumn, ColumnarError>

Read a single column, decoding all blocks.

col_idx is the column index in the footer’s column metadata.

pub fn read_column_filtered( &self, col_idx: usize, predicates: &[ScanPredicate], ) -> Result<DecodedColumn, ColumnarError>

Read a single column with predicate pushdown.

Blocks whose stats satisfy the predicates are skipped. For skipped blocks, null/zero-fill rows are emitted to preserve row alignment across projected columns.

pub fn read_columns( &self, col_indices: &[usize], predicates: &[ScanPredicate], ) -> Result<Vec<DecodedColumn>, ColumnarError>

Read multiple columns with shared predicate pushdown.

All columns share the same block skip decisions so row alignment is maintained across the result set.

pub fn read_column_with_deletes( &self, col_idx: usize, predicates: &[ScanPredicate], deletes: &DeleteBitmap, ) -> Result<DecodedColumn, ColumnarError>

Read a column with both predicate pushdown and delete bitmap masking.

Deleted rows have their validity set to false in the output. Fully deleted blocks are skipped entirely (no decompression).

pub fn read_columns_with_deletes( &self, col_indices: &[usize], predicates: &[ScanPredicate], deletes: &DeleteBitmap, ) -> Result<Vec<DecodedColumn>, ColumnarError>

Read multiple columns with predicate pushdown and delete bitmap.