feat: support information_schema.schemata (#18709)

e2e_test/batch/catalog/pg_class.slt.part

@@ -2,22 +2,22 @@ query ITIT
 SELECT oid,relname,relowner,relkind FROM pg_catalog.pg_class ORDER BY oid limit 15;
 ----
 2147478647 columns 1 v
-2147478648 tables 1 v
-2147478649 views 1 v
-2147478650 pg_am 1 v
-2147478651 pg_attrdef 1 v
-2147478652 pg_attribute 1 v
-2147478653 pg_auth_members 1 v
-2147478654 pg_cast 1 r
-2147478655 pg_class 1 v
-2147478656 pg_collation 1 v
-2147478657 pg_constraint 1 r
-2147478658 pg_conversion 1 v
-2147478659 pg_database 1 v
-2147478660 pg_depend 1 v
-2147478661 pg_description 1 v
+2147478648 schemata 1 v
+2147478649 tables 1 v
+2147478650 views 1 v
+2147478651 pg_am 1 v
+2147478652 pg_attrdef 1 v
+2147478653 pg_attribute 1 v
+2147478654 pg_auth_members 1 v
+2147478655 pg_cast 1 r
+2147478656 pg_class 1 v
+2147478657 pg_collation 1 v
+2147478658 pg_constraint 1 r
+2147478659 pg_conversion 1 v
+2147478660 pg_database 1 v
+2147478661 pg_depend 1 v
 
 query ITIT
 SELECT oid,relname,relowner,relkind FROM pg_catalog.pg_class WHERE oid = 'pg_namespace'::regclass;
 ----
-2147478670 pg_namespace 1 v
+2147478671 pg_namespace 1 v

e2e_test/ddl/schema.slt

@@ -88,6 +88,16 @@ public
 rw_catalog
 user_for_authorization
 
+query T rowsort
+select schema_name from information_schema.schemata;
+----
+information_schema
+myschema
+pg_catalog
+public
+rw_catalog
+user_for_authorization
+
 statement error Permission denied
 drop user user_for_authorization;
 

src/frontend/src/catalog/system_catalog/information_schema/mod.rs

@@ -13,5 +13,6 @@
 // limitations under the License.
 
 mod columns;
+mod schemata;
 mod tables;
 mod views;

src/frontend/src/catalog/system_catalog/information_schema/schemata.rs

@@ -0,0 +1,44 @@
+// Copyright 2024 RisingWave Labs
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use risingwave_common::types::Fields;
+use risingwave_frontend_macro::system_catalog;
+
+/// The view schemata contains all schemas in the current database that the current user has access to (by way of being the owner or having some privilege).
+/// Ref: [`https://www.postgresql.org/docs/current/infoschema-schemata.html`]
+#[system_catalog(
+    view,
+    "information_schema.schemata",
+    "SELECT CURRENT_DATABASE() AS catalog_name,
+            s.name AS schema_name,
+            u.name AS schema_owner,
+            NULL,
+            NULL,
+            NULL,
+            NULL
+        FROM rw_catalog.rw_schemas s
+        JOIN rw_catalog.rw_users u ON s.owner = u.id
+        WHERE has_schema_privilege(s.name, 'CREATE, USAGE')
+        ORDER BY catalog_name, schema_name"
+)]
+#[derive(Fields)]
+struct Schemata {
+    catalog_name: String,
+    schema_name: String,
+    schema_owner: String,
+    default_character_set_catalog: String,
+    default_character_set_schema: String,
+    default_character_set_name: String,
+    sql_path: String,
+}