validate index settings on create

src/core/index.rs

@@ -19,7 +19,7 @@ use crate::error::{DataCorruption, TantivyError};
 use crate::indexer::index_writer::{MAX_NUM_THREAD, MEMORY_ARENA_NUM_BYTES_MIN};
 use crate::indexer::segment_updater::save_metas;
 use crate::reader::{IndexReader, IndexReaderBuilder};
-use crate::schema::{Field, FieldType, Schema};
+use crate::schema::{Cardinality, Field, FieldType, Schema};
 use crate::tokenizer::{TextAnalyzer, TokenizerManager};
 use crate::IndexWriter;
 
@@ -152,9 +152,7 @@ impl IndexBuilder {
     /// This should only be used for unit tests.
     pub fn create_in_ram(self) -> Result<Index, TantivyError> {
         let ram_directory = RamDirectory::create();
-        Ok(self
-            .create(ram_directory)
-            .expect("Creating a RamDirectory should never fail"))
+        self.create(ram_directory)
     }
 
     /// Creates a new index in a given filepath.
@@ -228,10 +226,44 @@ impl IndexBuilder {
             ))
         }
     }
+
+    fn validate(&self) -> crate::Result<()> {
+        if let Some(schema) = self.schema.as_ref() {
+            if let Some(sort_by_field) = self.index_settings.sort_by_field.as_ref() {
+                let schema_field = schema.get_field(&sort_by_field.field).ok_or_else(|| {
+                    TantivyError::InvalidArgument(format!(
+                        "Field to sort index {} not found in schema",
+                        sort_by_field.field
+                    ))
+                })?;
+                let entry = schema.get_field_entry(schema_field);
+                if !entry.is_fast() {
+                    return Err(TantivyError::InvalidArgument(format!(
+                        "Field {} is no fast field. Field needs to be a single value fast field \
+                         to be used to sort an index",
+                        sort_by_field.field
+                    )));
+                }
+                if entry.field_type().fastfield_cardinality() != Some(Cardinality::SingleValue) {
+                    return Err(TantivyError::InvalidArgument(format!(
+                        "Only single value fast field Cardinality supported for sorting index {}",
+                        sort_by_field.field
+                    )));
+                }
+            }
+            Ok(())
+        } else {
+            Err(TantivyError::InvalidArgument(
+                "no schema passed".to_string(),
+            ))
+        }
+    }
+
     /// Creates a new index given an implementation of the trait `Directory`.
     ///
     /// If a directory previously existed, it will be erased.
     fn create<T: Into<Box<dyn Directory>>>(self, dir: T) -> crate::Result<Index> {
+        self.validate()?;
         let dir = dir.into();
         let directory = ManagedDirectory::wrap(dir)?;
         save_new_metas(

src/indexer/index_writer.rs

@@ -1395,6 +1395,35 @@ mod tests {
         assert!(commit_again.is_ok());
     }
 
+    #[test]
+    fn test_sort_by_multivalue_field_error() -> crate::Result<()> {
+        let mut schema_builder = schema::Schema::builder();
+        let options = NumericOptions::default().set_fast(Cardinality::MultiValues);
+        schema_builder.add_u64_field("id", options);
+        let schema = schema_builder.build();
+
+        let settings = IndexSettings {
+            sort_by_field: Some(IndexSortByField {
+                field: "id".to_string(),
+                order: Order::Desc,
+            }),
+            ..Default::default()
+        };
+
+        let err = Index::builder()
+            .schema(schema)
+            .settings(settings)
+            .create_in_ram()
+            .unwrap_err();
+        assert_eq!(
+            err.to_string(),
+            "An invalid argument was passed: 'Only single value fast field Cardinality supported \
+             for sorting index id'"
+        );
+
+        Ok(())
+    }
+
     #[test]
     fn test_delete_with_sort_by_field() -> crate::Result<()> {
         let mut schema_builder = schema::Schema::builder();

src/query/set_query.rs

@@ -43,7 +43,6 @@ impl TermSetQuery {
                 let error_msg = format!("Field {:?} is not indexed.", field_entry.name());
                 return Err(crate::TantivyError::SchemaError(error_msg));
             }
-            let field_type = field_type.value_type();
 
             // In practice this won't fail because:
             // - we are writing to memory, so no IoError

src/schema/field_type.rs

@@ -2,6 +2,7 @@ use serde::{Deserialize, Serialize};
 use serde_json::Value as JsonValue;
 use thiserror::Error;
 
+use super::Cardinality;
 use crate::schema::bytes_options::BytesOptions;
 use crate::schema::facet_options::FacetOptions;
 use crate::schema::{
@@ -214,6 +215,26 @@ impl FieldType {
         }
     }
 
+    /// returns true if the field is fast.
+    pub fn fastfield_cardinality(&self) -> Option<Cardinality> {
+        match *self {
+            FieldType::Bytes(ref bytes_options) if bytes_options.is_fast() => {
+                Some(Cardinality::SingleValue)
+            }
+            FieldType::Str(ref text_options) if text_options.is_fast() => {
+                Some(Cardinality::MultiValues)
+            }
+            FieldType::U64(ref int_options)
+            | FieldType::I64(ref int_options)
+            | FieldType::F64(ref int_options)
+            | FieldType::Bool(ref int_options) => int_options.get_fastfield_cardinality(),
+            FieldType::Date(ref date_options) => date_options.get_fastfield_cardinality(),
+            FieldType::Facet(_) => Some(Cardinality::MultiValues),
+            FieldType::JsonObject(_) => None,
+            _ => None,
+        }
+    }
+
     /// returns true if the field is normed (see [fieldnorms](crate::fieldnorm)).
     pub fn has_fieldnorms(&self) -> bool {
         match *self {