Dumpless upgrade

crates/milli/src/update/upgrade/v1_15.rs

@@ -0,0 +1,35 @@
+use heed::RwTxn;
+
+use super::UpgradeIndex;
+use crate::progress::Progress;
+use crate::update::new::indexer::recompute_word_fst_from_word_docids_database;
+use crate::{make_enum_progress, Index, Result};
+
+#[allow(non_camel_case_types)]
+pub(super) struct Latest_V1_14_To_Latest_V1_15();
+
+impl UpgradeIndex for Latest_V1_14_To_Latest_V1_15 {
+    fn upgrade(
+        &self,
+        wtxn: &mut RwTxn,
+        index: &Index,
+        _original: (u32, u32, u32),
+        progress: Progress,
+    ) -> Result<bool> {
+        // Recompute the word FST from the word docids database.
+        make_enum_progress! {
+            enum TypoTolerance {
+                RecomputeWordFst,
+            }
+        };
+
+        progress.update_progress(TypoTolerance::RecomputeWordFst);
+        recompute_word_fst_from_word_docids_database(index, wtxn)?;
+
+        Ok(false)
+    }
+
+    fn target_version(&self) -> (u32, u32, u32) {
+        (1, 15, 0)
+    }
+}