Method remap_segment

nodedb-columnar/src/pk_index.rs:97–116

Remap all entries pointing to `old_segment_id` using a provided function. Used after compaction: old segment IDs are replaced with new ones, and row indices may shift. The `remap_fn` returns `None` to remove the entry (row was deleted during compaction) or `Some(new_location)`.

(
        &mut self,
        old_segment_id: u64,
        remap_fn: impl Fn(u32) -> Option<RowLocation>,
    )

    /// and row indices may shift. The `remap_fn` returns `None` to remove
    /// the entry (row was deleted during compaction) or `Some(new_location)`.
    pub fn remap_segment(
        &mut self,
        old_segment_id: u64,
        remap_fn: impl Fn(u32) -> Option<RowLocation>,
    ) {
        let keys_to_remap: Vec<Vec<u8>> = self
            .inner
            .iter()
            .filter(|(_, loc)| loc.segment_id == old_segment_id)
            .map(|(k, _)| k.clone())
            .collect();

        for key in keys_to_remap {
            let old_loc = self.inner.remove(&key).expect("key exists from filter");
            if let Some(new_loc) = remap_fn(old_loc.row_index) {
                self.inner.insert(key, new_loc);
            }
            // If remap_fn returns None, the entry is dropped (row was deleted).
        }
    }

    /// Bulk insert entries for a newly flushed segment.
    ///