pub const SPAN_STEP_BYTES: u64 = _ /* 1_048_576u64 */;Expand description
How many bytes of a transcript one paging pass reads before growing, and how wide a single window it takes may be.
A page below the window’s floor lies near the file’s END: the floor is the oldest frame the window still holds, so the turns above it are the newest rows of a file the session is still writing - some 4,000 rows, a few hundred KB at the rows a transcript writes. The step is what a cold session pays for its first paging request.
The cap bounds one WINDOW, not the pass. A read that comes up short doubles and reads again, so a walk that reaches the cap has read the windows under it as well - up to about twice this, and the anchor search pays the same. What is capped is therefore how far a single window reaches, and past it the transcript is treated as unreadable for paging rather than read whole.