Expand description
Lightweight SQLite page classification for prefetch planning. Lightweight SQLite page classification for the VFS prefetch planner.
A table scan over rows with overflowing payloads reads B-tree leaf pages and
overflow pages interleaved (for example leaf 2, overflow 20, leaf 3, overflow 21). The two classes usually live in separate physical regions, so
a single stride/forward-scan tracker sees large alternating deltas and never
detects the per-class monotonic scan. Classifying each accessed page lets the
planner keep one tracker per class so the leaf scan can escalate read-ahead
independently of the overflow accesses.
Enums§
- Page
Class - Coarse page classification used to separate prefetch tracking streams. Any
page that is not a B-tree page (overflow, freelist, or pointer-map) falls
into
PageClass::Overflow.
Functions§
- classify
- Classify a page from its raw bytes using the one-byte B-tree page type at the header offset (0x02 interior index, 0x05 interior table, 0x0a leaf index, 0x0d leaf table). Page 1 carries the 100-byte database header before its B-tree header. Any other type byte is treated as a non-B-tree page.