use std::sync::Arc;
use fastfield_codecs::Column;
use itertools::Itertools;
use crate::indexer::doc_id_mapping::SegmentDocIdMapping;
use crate::schema::Field;
use crate::SegmentReader;
pub(crate) struct RemappedDocIdColumn<'a> {
doc_id_mapping: &'a SegmentDocIdMapping,
fast_field_readers: Vec<Arc<dyn Column<u64>>>,
min_value: u64,
max_value: u64,
num_vals: u32,
}
fn compute_min_max_val(
u64_reader: &dyn Column<u64>,
segment_reader: &SegmentReader,
) -> Option<(u64, u64)> {
if segment_reader.max_doc() == 0 {
return None;
}
if segment_reader.alive_bitset().is_none() {
return Some((u64_reader.min_value(), u64_reader.max_value()));
}
segment_reader
.doc_ids_alive()
.map(|doc_id| u64_reader.get_val(doc_id))
.minmax()
.into_option()
}
impl<'a> RemappedDocIdColumn<'a> {
pub(crate) fn new(
readers: &'a [SegmentReader],
doc_id_mapping: &'a SegmentDocIdMapping,
field: Field,
) -> Self {
let (min_value, max_value) = readers
.iter()
.filter_map(|reader| {
let u64_reader: Arc<dyn Column<u64>> =
reader.fast_fields().typed_fast_field_reader(field).expect(
"Failed to find a reader for single fast field. This is a tantivy bug and \
it should never happen.",
);
compute_min_max_val(&*u64_reader, reader)
})
.reduce(|a, b| (a.0.min(b.0), a.1.max(b.1)))
.expect("Unexpected error, empty readers in IndexMerger");
let fast_field_readers = readers
.iter()
.map(|reader| {
let u64_reader: Arc<dyn Column<u64>> =
reader.fast_fields().typed_fast_field_reader(field).expect(
"Failed to find a reader for single fast field. This is a tantivy bug and \
it should never happen.",
);
u64_reader
})
.collect::<Vec<_>>();
RemappedDocIdColumn {
doc_id_mapping,
fast_field_readers,
min_value,
max_value,
num_vals: doc_id_mapping.len() as u32,
}
}
}
impl<'a> Column for RemappedDocIdColumn<'a> {
fn get_val(&self, _doc: u32) -> u64 {
unimplemented!()
}
fn iter(&self) -> Box<dyn Iterator<Item = u64> + '_> {
Box::new(
self.doc_id_mapping
.iter_old_doc_addrs()
.map(|old_doc_addr| {
let fast_field_reader =
&self.fast_field_readers[old_doc_addr.segment_ord as usize];
fast_field_reader.get_val(old_doc_addr.doc_id)
}),
)
}
fn min_value(&self) -> u64 {
self.min_value
}
fn max_value(&self) -> u64 {
self.max_value
}
fn num_vals(&self) -> u32 {
self.num_vals
}
}