Fix vector error messages

crates/milli/src/update/new/extract/vectors/mod.rs

@@ -151,6 +151,7 @@ impl<'a, 'extractor> Extractor<'extractor> for EmbeddingExtractor<'a> {
                                 if new_rendered != old_rendered {
                                     chunks.set_autogenerated(
                                         update.docid(),
+                                        update.external_document_id(),
                                         new_rendered,
                                         &unused_vectors_distribution,
                                     )?;
@@ -178,6 +179,7 @@ impl<'a, 'extractor> Extractor<'extractor> for EmbeddingExtractor<'a> {
                             if new_rendered != old_rendered {
                                 chunks.set_autogenerated(
                                     update.docid(),
+                                    update.external_document_id(),
                                     new_rendered,
                                     &unused_vectors_distribution,
                                 )?;
@@ -221,6 +223,7 @@ impl<'a, 'extractor> Extractor<'extractor> for EmbeddingExtractor<'a> {
                                 )?;
                                 chunks.set_autogenerated(
                                     insertion.docid(),
+                                    insertion.external_document_id(),
                                     rendered,
                                     &unused_vectors_distribution,
                                 )?;
@@ -233,6 +236,7 @@ impl<'a, 'extractor> Extractor<'extractor> for EmbeddingExtractor<'a> {
                             )?;
                             chunks.set_autogenerated(
                                 insertion.docid(),
+                                insertion.external_document_id(),
                                 rendered,
                                 &unused_vectors_distribution,
                             )?;
@@ -268,6 +272,7 @@ struct Chunks<'a, 'extractor> {
     user_provided: &'a RefCell<EmbeddingExtractorData<'extractor>>,
     threads: &'a ThreadPoolNoAbort,
     sender: &'a EmbeddingSender<'a>,
+    has_manual_generation: Option<&'a str>,
 }
 
 impl<'a, 'extractor> Chunks<'a, 'extractor> {
@@ -297,15 +302,22 @@ impl<'a, 'extractor> Chunks<'a, 'extractor> {
             embedder_id,
             embedder_name,
             user_provided,
+            has_manual_generation: None,
         }
     }
 
     pub fn set_autogenerated(
         &mut self,
         docid: DocumentId,
+        external_docid: &'a str,
         rendered: &'a str,
         unused_vectors_distribution: &UnusedVectorsDistributionBump,
     ) -> Result<()> {
+        let is_manual = matches!(&self.embedder, &Embedder::UserProvided(_));
+        if is_manual {
+            self.has_manual_generation.get_or_insert(external_docid);
+        }
+
         if self.texts.len() < self.texts.capacity() {
             self.texts.push(rendered);
             self.ids.push(docid);
@@ -322,6 +334,7 @@ impl<'a, 'extractor> Chunks<'a, 'extractor> {
             unused_vectors_distribution,
             self.threads,
             self.sender,
+            self.has_manual_generation.take(),
         )
     }
 
@@ -339,6 +352,7 @@ impl<'a, 'extractor> Chunks<'a, 'extractor> {
             unused_vectors_distribution,
             self.threads,
             self.sender,
+            self.has_manual_generation,
         );
         // optimization: don't run bvec dtors as they only contain bumpalo allocated stuff
         std::mem::forget(self);
@@ -356,7 +370,46 @@ impl<'a, 'extractor> Chunks<'a, 'extractor> {
         unused_vectors_distribution: &UnusedVectorsDistributionBump,
         threads: &ThreadPoolNoAbort,
         sender: &EmbeddingSender<'a>,
+        has_manual_generation: Option<&'a str>,
     ) -> Result<()> {
+        if let Some(external_docid) = has_manual_generation {
+            let mut msg = format!(
+                r"While embedding documents for embedder `{embedder_name}`: no vectors provided for document `{}`{}",
+                external_docid,
+                if ids.len() > 1 {
+                    format!(" and at least {} other document(s)", ids.len() - 1)
+                } else {
+                    "".to_string()
+                }
+            );
+
+            msg += &format!("\n- Note: `{embedder_name}` has `source: userProvided`, so documents must provide embeddings as an array in `_vectors.{embedder_name}`.");
+
+            let mut hint_count = 0;
+
+            for (vector_misspelling, count) in possible_embedding_mistakes.vector_mistakes().take(2)
+            {
+                msg += &format!("\n- Hint: try replacing `{vector_misspelling}` by `_vectors` in {count} document(s).");
+                hint_count += 1;
+            }
+
+            for (embedder_misspelling, count) in possible_embedding_mistakes
+                .embedder_mistakes_bump(embedder_name, unused_vectors_distribution)
+                .take(2)
+            {
+                msg += &format!("\n- Hint: try replacing `_vectors.{embedder_misspelling}` by `_vectors.{embedder_name}` in {count} document(s).");
+                hint_count += 1;
+            }
+
+            if hint_count == 0 {
+                msg += &format!(
+                    "\n- Hint: opt-out for a document with `_vectors.{embedder_name}: null`"
+                );
+            }
+
+            return Err(crate::Error::UserError(crate::UserError::DocumentEmbeddingError(msg)));
+        }
+
         let res = match embedder.embed_chunks_ref(texts.as_slice(), threads) {
             Ok(embeddings) => {
                 for (docid, embedding) in ids.into_iter().zip(embeddings) {

crates/milli/src/vector/mod.rs

@@ -648,7 +648,7 @@ impl Embedder {
             Embedder::HuggingFace(embedder) => embedder.chunk_count_hint(),
             Embedder::OpenAi(embedder) => embedder.chunk_count_hint(),
             Embedder::Ollama(embedder) => embedder.chunk_count_hint(),
-            Embedder::UserProvided(_) => 1,
+            Embedder::UserProvided(_) => 100,
             Embedder::Rest(embedder) => embedder.chunk_count_hint(),
         }
     }