Fix off by one in optional index

Fixes #2293

Fixes an off by one error in the metadata resize of the optional index
when loading the index.

Merge variables with the same meaning but different names

columnar/src/column/mod.rs

@@ -110,6 +110,9 @@ impl<T: PartialOrd + Copy + Debug + Send + Sync + 'static> Column<T> {
     }
 
     /// Get the docids of values which are in the provided value range.
+    ///
+    /// # Panic
+    /// Panics if a value in the selected_docid_range range is larger than the number of documents.
     #[inline]
     pub fn get_docids_for_value_range(
         &self,

columnar/src/column_index/mod.rs

@@ -126,6 +126,8 @@ impl ColumnIndex {
         }
     }
 
+    /// # Panic
+    /// Panics if a value in the doc_id range is larger than the number of documents.
     pub fn docid_range_to_rowids(&self, doc_id: Range<DocId>) -> Range<RowId> {
         match self {
             ColumnIndex::Empty { .. } => 0..0,

columnar/src/column_index/optional_index/mod.rs

@@ -21,8 +21,6 @@ const DENSE_BLOCK_THRESHOLD: u32 =
 
 const ELEMENTS_PER_BLOCK: u32 = u16::MAX as u32 + 1;
 
-const BLOCK_SIZE: RowId = 1 << 16;
-
 #[derive(Copy, Clone, Debug)]
 struct BlockMeta {
     non_null_rows_before_block: u32,
@@ -109,8 +107,8 @@ struct RowAddr {
 #[inline(always)]
 fn row_addr_from_row_id(row_id: RowId) -> RowAddr {
     RowAddr {
-        block_id: (row_id / BLOCK_SIZE) as u16,
-        in_block_row_id: (row_id % BLOCK_SIZE) as u16,
+        block_id: (row_id / ELEMENTS_PER_BLOCK) as u16,
+        in_block_row_id: (row_id % ELEMENTS_PER_BLOCK) as u16,
     }
 }
 
@@ -490,8 +488,9 @@ fn deserialize_optional_index_block_metadatas(
         start_byte_offset += block_variant.num_bytes_in_block();
         non_null_rows_before_block += num_non_null_rows;
     }
+    let last_block = row_addr_from_row_id(num_rows).block_id;
     block_metas.resize(
-        ((num_rows + BLOCK_SIZE - 1) / BLOCK_SIZE) as usize,
+        last_block as usize + 1, // +1 since last block is an index
         BlockMeta {
             non_null_rows_before_block,
             start_byte_offset,

columnar/src/column_index/optional_index/tests.rs

@@ -3,6 +3,29 @@ use proptest::strategy::Strategy;
 use proptest::{prop_oneof, proptest};
 
 use super::*;
+use crate::{ColumnarReader, ColumnarWriter, DynamicColumnHandle};
+
+#[test]
+fn test_optional_index_bug_2293() {
+    test_optional_index_with_num_docs(ELEMENTS_PER_BLOCK - 1);
+    test_optional_index_with_num_docs(ELEMENTS_PER_BLOCK);
+    test_optional_index_with_num_docs(ELEMENTS_PER_BLOCK + 1);
+}
+fn test_optional_index_with_num_docs(num_docs: u32) {
+    let mut dataframe_writer = ColumnarWriter::default();
+    dataframe_writer.record_numerical(100, "score", 80i64);
+    let mut buffer: Vec<u8> = Vec::new();
+    dataframe_writer
+        .serialize(num_docs, None, &mut buffer)
+        .unwrap();
+    let columnar = ColumnarReader::open(buffer).unwrap();
+    assert_eq!(columnar.num_columns(), 1);
+    let cols: Vec<DynamicColumnHandle> = columnar.read_columns("score").unwrap();
+    assert_eq!(cols.len(), 1);
+
+    let col = cols[0].open().unwrap();
+    col.column_index().docid_range_to_rowids(0..num_docs);
+}
 
 #[test]
 fn test_dense_block_threshold() {
@@ -35,7 +58,7 @@ proptest! {
 
 #[test]
 fn test_with_random_sets_simple() {
-    let vals = 10..BLOCK_SIZE * 2;
+    let vals = 10..ELEMENTS_PER_BLOCK * 2;
     let mut out: Vec<u8> = Vec::new();
     serialize_optional_index(&vals, 100, &mut out).unwrap();
     let null_index = open_optional_index(OwnedBytes::new(out)).unwrap();
@@ -171,7 +194,7 @@ fn test_optional_index_rank() {
     test_optional_index_rank_aux(&[0u32, 1u32]);
     let mut block = Vec::new();
     block.push(3u32);
-    block.extend((0..BLOCK_SIZE).map(|i| i + BLOCK_SIZE + 1));
+    block.extend((0..ELEMENTS_PER_BLOCK).map(|i| i + ELEMENTS_PER_BLOCK + 1));
     test_optional_index_rank_aux(&block);
 }
 
@@ -185,8 +208,8 @@ fn test_optional_index_iter_empty_one() {
 fn test_optional_index_iter_dense_block() {
     let mut block = Vec::new();
     block.push(3u32);
-    block.extend((0..BLOCK_SIZE).map(|i| i + BLOCK_SIZE + 1));
-    test_optional_index_iter_aux(&block, 3 * BLOCK_SIZE);
+    block.extend((0..ELEMENTS_PER_BLOCK).map(|i| i + ELEMENTS_PER_BLOCK + 1));
+    test_optional_index_iter_aux(&block, 3 * ELEMENTS_PER_BLOCK);
 }
 
 #[test]