fn truncate_times(
column: Column<(Row, Product<Timestamp, PointStamp<u64>>, Diff)>,
level: usize,
) -> Column<(Row, Product<Timestamp, PointStamp<u64>>, Diff)>Expand description
Truncates every time in column to level - 1 iteration coordinates.
A Typed input hands its row and diff columns over untouched, because truncation only
rewrites times. A serialized input keeps all three columns in one buffer, so its rows
and diffs are copied in bulk rather than per record.