Default page size in bytes (4096). The codec itself sizes to the actual buffer length (#95); runtime geometry lives in Geometry/Pager. This constant is the default value, used for building default-geometry pages (mainly in tests).

16 bytes — the common page header (geometry-independent).

16 — first byte of the data area (same as header_size).

4080 — usable data bytes for the DEFAULT 4096 geometry. For a runtime geometry use Geometry.max_data_bytes.

Kind of a page.

Common page header fields (bytes 0–15).

Read the 16-byte common header from buf. Raises Failure "invalid page kind" if the kind byte is not 0–3.

Write the 16-byte common header into buf. Zeros the 4-byte reserved field (bytes 12–15).

CRC32 (IEEE polynomial) of page, with crc32 field (bytes 8..11) zeroed

true if compute_crc buf equals the crc32 stored in the common header.

Compute CRC and write it into the page at bytes 8..11. Call after all other fields are written.

Write the per-tree schema-fingerprint stamp (#174) into the reserved bytes 12–15. Call AFTER write_common and BEFORE seal so the CRC covers it. 0 means "no stamp" (system trees, legacy pages).

Read the per-tree schema-fingerprint stamp from bytes 12–15 (#174).

Header page fields (kind = Header; bytes 16–103, remainder reserved).

Read header-page fields from buf (reads bytes 16–103).

Write header-page fields into buf. Zeros bytes 16–(page_size-1) first (including the reserved area 104+) to prevent stale data from corrupting the CRC, then writes the known fields into bytes 16–103.

A decoded branch page entry.

Branch page entry iteration.

Call repeatedly with increasing offset starting at data_offset. The caller is responsible for stopping after n_keys entries; `` `End`` is only returned when offset is truly out of the page bounds.

Returns `` `Entry branch_entry`` or `` `End``.

Append a branch entry at offset. Returns the next offset after the appended entry. The usable ceiling is Cstruct.length buf - reserved (reserved defaults to 0, #95); the page size is taken from the buffer. Raises Invalid_argument if the entry would overflow that ceiling or if key is longer than 65535 bytes.

A decoded leaf page entry.

Leaf page entry iteration.

Call repeatedly starting at data_offset. The caller is responsible for stopping after n_keys entries.

Returns `` `Entry leaf_entry`` or `` `End``.

Append a leaf entry at offset. Returns the next offset. The usable ceiling is Cstruct.length buf - reserved (reserved defaults to 0, #95); the page size is taken from the buffer. Raises Invalid_argument if the entry would overflow that ceiling or if key or value is longer than 65535 bytes.

In-place point lookup on a sorted leaf page (n_keys = common.n_keys). Returns the matching value (freshly copied) or None. Equivalent to decoding the full entry list and scanning it, but allocates ONLY the matched value — no entry list, and no key/value bytes for the entries it skips (#245). Bounds handling mirrors leaf_entry_at.

In-place branch child selection on a sorted branch page. Returns the child page-id (int32) to descend into for key — the left_child of the first entry whose key strictly exceeds key, else right_page (= common.right_page). Allocates nothing; byte-identical to the list-based pick (#245).

Result of leaf_find_position: where a key belongs in a sorted leaf page.

Zero-alloc scan to find where key belongs in a sorted leaf page. insert_off is the offset of the first entry >= key (or data_end). key_found is true iff an exact match exists at insert_off.

Build a new leaf page with (key, stored_value) inserted at pos.insert_off via byte-surgery (no entry decode/re-encode). Caller guarantees pos.key_found = false and the entry fits without split.

Insert (key, stored_value) into a sorted leaf page IN PLACE at pos.insert_off, shifting tail entries up and bumping n_keys. Mutates buf directly — used by the in-place insert fast path (#356) when the leaf is already owned by the current write txn. Caller guarantees pos.key_found = false and the entry fits. Preserves right_page and tag; CRC reseals at flush.

Zero-alloc test whether the leaf entry starting at byte offset has key equal to key. Bounds-checked (false on a malformed offset). Used to validate an append cursor against the live page (#356).

Like branch_pick but also returns the chosen child's ordinal index and byte offset of its left_child int32 field (-1 for right_page).

Build a new branch page identical to buf except the child pointer at child_ptr_offset is replaced with new_child (child_ptr_offset < 0 updates right_page instead). Returns a fresh, freshly-sealed Cstruct.

4080 / 12 = 340 freelist entries per page for the DEFAULT 4096 geometry. For a runtime geometry use Geometry.max_freelist_entries_per_page.

A decoded freelist page entry.

Read a freelist entry by 0-based index.

Write a freelist entry at 0-based index.

Maximum payload bytes per overflow page for the default 4096 geometry (4080 - 2). For a runtime geometry use Geometry.max_overflow_payload_bytes.

Read the payload length stored at bytes 16..17 of an Overflow page.

Slice the payload bytes from an Overflow page.

Write an overflow page: sets kind=Overflow, n_keys=0, right_page=next_pid, payload_len, and copies payload into the data area. The maximum payload is Cstruct.length buf - data_offset - 2 - reserved (reserved defaults to 0, #95). Does NOT seal — caller invokes seal.