Feat/normalize config identifiers

pgdog-config/src/util.rs

@@ -53,6 +53,26 @@ pub fn random_string(n: usize) -> String {
         .collect()
 }
 
+/// Fold a configured identifier the way PostgreSQL's parser folds
+/// identifiers in SQL, so values from `pgdog.toml` compare equal to
+/// the ones the query parser produces.
+///
+/// - Unquoted identifiers are lower-cased: `Orders` -> `orders`
+/// - Quoted identifiers keep their case, lose the surrounding quotes,
+///   and un-escape doubled quotes: `"Or""ders"` -> `Or"ders`
+///
+/// Folding is ASCII-only, matching PostgreSQL's behaviour for
+/// multi-byte encodings such as UTF-8.
+pub fn normalize_identifier(identifier: &str) -> String {
+    match identifier
+        .strip_prefix('"')
+        .and_then(|inner| inner.strip_suffix('"'))
+    {
+        Some(inner) => inner.replace("\"\"", "\""),
+        None => identifier.to_ascii_lowercase(),
+    }
+}
+
 /// Swap field values using tmp pattern: source -> tmp, dest -> source, tmp -> dest.
 #[macro_export]
 macro_rules! swap_field {
@@ -74,3 +94,47 @@ macro_rules! swap_field {
         });
     };
 }
+
+#[cfg(test)]
+mod test_normalize_identifier {
+    use super::normalize_identifier;
+
+    #[test]
+    fn test_unquoted_is_lowercased() {
+        assert_eq!(normalize_identifier("Orders"), "orders");
+        assert_eq!(normalize_identifier("ORDERS"), "orders");
+        assert_eq!(normalize_identifier("orders"), "orders");
+        assert_eq!(normalize_identifier("Tenant_Id"), "tenant_id");
+    }
+
+    #[test]
+    fn test_quoted_preserves_case_and_drops_quotes() {
+        assert_eq!(normalize_identifier(r#""Orders""#), "Orders");
+        assert_eq!(normalize_identifier(r#""ORDERS""#), "ORDERS");
+        assert_eq!(normalize_identifier(r#""orders""#), "orders");
+    }
+
+    #[test]
+    fn test_quoted_unescapes_doubled_quotes() {
+        assert_eq!(normalize_identifier(r#""Or""ders""#), r#"Or"ders"#);
+        assert_eq!(
+            normalize_identifier(r#""He said ""hi""""#),
+            r#"He said "hi""#
+        );
+    }
+
+    #[test]
+    fn test_folding_is_ascii_only() {
+        // PostgreSQL folds only ASCII in multi-byte encodings, so the
+        // accented character is left alone while ECOLE is lowered.
+        assert_eq!(normalize_identifier("ÉCOLE"), "École");
+    }
+
+    #[test]
+    fn test_edge_cases() {
+        assert_eq!(normalize_identifier(""), "");
+        assert_eq!(normalize_identifier(r#""""#), "");
+        // A lone quote is not a valid quoted identifier; treat it as unquoted.
+        assert_eq!(normalize_identifier(r#""Orders"#), r#""orders"#);
+    }
+}

pgdog/src/backend/databases.rs

@@ -11,6 +11,7 @@ use once_cell::sync::Lazy;
 use parking_lot::lock_api::MutexGuard;
 use parking_lot::{Mutex, RawMutex};
 use pgdog_config::users::PasswordKind;
+use pgdog_config::util::normalize_identifier;
 use pgdog_config::{
     QueryParser, ShardedMappingConfig, ShardedMappingKey, ShardedMappingKeyRef,
     ShardedMappingKindDeprecated, ShardedMappingList, ShardedMappingRange, ShardedTableConfig,
@@ -507,9 +508,9 @@ fn resolve_sharded_table(
 
     ShardedTable {
         database: config.database.clone(),
-        name: config.name.clone(),
-        schema: config.schema.clone(),
-        column: config.column.clone(),
+        name: config.name.as_deref().map(normalize_identifier),
+        schema: config.schema.as_deref().map(normalize_identifier),
+        column: normalize_identifier(&config.column),
         primary: config.primary,
         centroids: config.centroids.clone(),
         data_type: config.data_type,
@@ -1987,4 +1988,44 @@ password = "testpass"
         assert_eq!(new_users.users[0].name, "testuser");
         assert_eq!(new_users.users[0].database, "destination_db");
     }
+
+    /// PostgreSQL folds unquoted identifiers to lower case, so the parser
+    /// hands the router `orders` for `FROM Orders`. Identifiers configured
+    /// in `pgdog.toml` must be folded the same way, otherwise they never
+    /// match and the table silently isn't sharded.
+    #[test]
+    fn test_unquoted_config_identifiers_are_folded() {
+        let config = ShardedTableConfig {
+            database: "pgdog".into(),
+            name: Some("Orders".into()),
+            schema: Some("Public".into()),
+            column: "Tenant_Id".into(),
+            ..Default::default()
+        };
+
+        let resolved = resolve_sharded_table(&config, &IndexMap::new(), 2);
+
+        assert_eq!(resolved.name.as_deref(), Some("orders"));
+        assert_eq!(resolved.schema.as_deref(), Some("public"));
+        assert_eq!(resolved.column, "tenant_id");
+    }
+
+    /// Quoted identifiers keep their case, and the surrounding quotes are
+    /// not part of the identifier itself.
+    #[test]
+    fn test_quoted_config_identifiers_preserve_case() {
+        let config = ShardedTableConfig {
+            database: "pgdog".into(),
+            name: Some(r#""Orders""#.into()),
+            schema: Some(r#""Public""#.into()),
+            column: r#""Tenant_Id""#.into(),
+            ..Default::default()
+        };
+
+        let resolved = resolve_sharded_table(&config, &IndexMap::new(), 2);
+
+        assert_eq!(resolved.name.as_deref(), Some("Orders"));
+        assert_eq!(resolved.schema.as_deref(), Some("Public"));
+        assert_eq!(resolved.column, "Tenant_Id");
+    }
 }