use correct precision level for fastfield-based termquery on datetime (#6027)

Author: trinity-1686a

quickwit/quickwit-query/src/query_ast/full_text_query.rs

@@ -301,7 +301,7 @@ impl FullTextQuery {
 
 #[cfg(test)]
 mod tests {
-    use tantivy::schema::{Schema, TEXT};
+    use tantivy::schema::{DateOptions, DateTimePrecision, Schema, TEXT};
 
     use crate::BooleanOperand;
     use crate::query_ast::tantivy_query_ast::TantivyQueryAst;
@@ -379,6 +379,59 @@ mod tests {
         );
     }
 
+    #[test]
+    fn test_full_text_datetime() {
+        let full_text_query = FullTextQuery {
+            field: "ts".to_string(),
+            text: "2025-12-13T16:13:12.666777Z".to_string(),
+            params: super::FullTextParams {
+                tokenizer: Some("raw".to_string()),
+                mode: FullTextMode::Phrase { slop: 1 },
+                zero_terms_query: crate::MatchAllOrNone::MatchAll,
+            },
+            lenient: false,
+        };
+        {
+            // indexed, we truncate to the second
+            let mut schema_builder = Schema::builder();
+            schema_builder.add_date_field(
+                "ts",
+                DateOptions::default()
+                    .set_precision(DateTimePrecision::Milliseconds)
+                    .set_fast()
+                    .set_indexed(),
+            );
+            let schema = schema_builder.build();
+            let ast: TantivyQueryAst = full_text_query
+                .build_tantivy_ast_call(&BuildTantivyAstContext::for_test(&schema))
+                .unwrap();
+            let leaf = ast.as_leaf().unwrap();
+            assert_eq!(
+                &format!("{leaf:?}"),
+                r#"TermQuery(Term(field=0, type=Date, 2025-12-13T16:13:12Z))"#
+            );
+        }
+        {
+            // not indexed, we truncate to fastfield precision
+            let mut schema_builder = Schema::builder();
+            schema_builder.add_date_field(
+                "ts",
+                DateOptions::default()
+                    .set_precision(DateTimePrecision::Milliseconds)
+                    .set_fast(),
+            );
+            let schema = schema_builder.build();
+            let ast: TantivyQueryAst = full_text_query
+                .build_tantivy_ast_call(&BuildTantivyAstContext::for_test(&schema))
+                .unwrap();
+            let leaf = ast.as_leaf().unwrap();
+            assert_eq!(
+                &format!("{leaf:?}"),
+                r#"TermQuery(Term(field=0, type=Date, 2025-12-13T16:13:12.666Z))"#
+            );
+        }
+    }
+
     #[test]
     fn test_full_text_bool_mode() {
         let full_text_query = FullTextQuery {

quickwit/quickwit-query/src/query_ast/utils.rs

@@ -141,9 +141,13 @@ fn compute_query_with_field(
             let term = Term::from_field_bool(field, bool_val);
             Ok(make_term_query(term))
         }
-        FieldType::Date(_) => {
+        FieldType::Date(date_options) => {
             let dt = parse_value_from_user_text(value, field_entry.name())?;
-            let term = Term::from_field_date_for_search(field, dt);
+            let term = if date_options.is_indexed() {
+                Term::from_field_date_for_search(field, dt)
+            } else {
+                Term::from_field_date(field, dt.truncate(date_options.get_precision()))
+            };
             Ok(make_term_query(term))
         }
         FieldType::Str(text_options) => {