Struct PageHeader 

pub struct PageHeader {
    pub page_type: PageType,
    pub flags: u8,
    pub cell_count: u16,
    pub free_start: u16,
    pub free_end: u16,
    pub page_id: u32,
    pub parent_id: u32,
    pub right_child: u32,
    pub lsn: u64,
    pub checksum: u32,
}

Page header structure (32 bytes)

Layout:

Offset  Size  Field
------  ----  -----
  0      1    page_type
  1      1    flags
  2      2    cell_count
  4      2    free_start (offset to first free byte in cell pointer array)
  6      2    free_end (offset to first free byte before cell content)
  8      4    page_id
 12      4    parent_id (0 for root)
 16      4    right_child (for interior nodes, 0 otherwise)
 20      8    lsn (Log Sequence Number for WAL)
 28      4    checksum (CRC32 of content)

Fields

page_type: PageType

Type of this page

flags: u8

Page flags (dirty, locked, etc.)

cell_count: u16

Number of cells on this page

free_start: u16

Offset to start of free space (cell pointer array end)

free_end: u16

Offset to end of free space (cell content start)

page_id: u32

Unique page identifier

parent_id: u32

Parent page ID (0 for root or orphan)

right_child: u32

Right-most child page (interior nodes only)

lsn: u64

Log Sequence Number (for WAL ordering)

checksum: u32

CRC32 checksum of page content

Implementations

impl PageHeader

pub fn new(page_type: PageType, page_id: u32) -> PageHeader

Create a new header for an empty page

pub fn to_bytes(&self) -> [u8; 32]

Serialize header to bytes

pub fn from_bytes(buf: &[u8; 32]) -> Result<PageHeader, PageError>

Deserialize header from bytes

pub fn has_flag(&self, flag: PageFlag) -> bool

Check if page has specific flag

pub fn set_flag(&mut self, flag: PageFlag)

Set a flag

pub fn clear_flag(&mut self, flag: PageFlag)

Clear a flag

pub fn free_space(&self) -> usize

Calculate free space available for new cells

Trait Implementations

impl Clone for PageHeader

fn clone(&self) -> PageHeader

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for PageHeader

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl Copy for PageHeader