feat: expose PK info in index system catalog

e2e_test/batch/catalog/pg_indexes.slt.part

@@ -1,5 +1,5 @@
 statement ok
-create table t(a int, b int);
+create table t(a int primary key, b int);
 
 statement ok
 create index idx1 on t(a);
@@ -12,6 +12,7 @@ select schemaname, tablename, indexname, tablespace, indexdef from pg_catalog.pg
 ----
 public t idx1 NULL CREATE INDEX idx1 ON t(a)
 public t idx2 NULL CREATE INDEX idx2 ON t(b)
+public t t_pkey NULL (empty)
 
 statement ok
 drop table t;

src/frontend/src/catalog/system_catalog/pg_catalog/pg_index.rs

@@ -39,7 +39,34 @@ use risingwave_frontend_macro::system_catalog;
         true AS indisready,
         true AS indislive,
         false AS indisreplident
-    FROM rw_catalog.rw_indexes"
+    FROM rw_catalog.rw_indexes
+    UNION ALL
+    SELECT c.relation_id AS indexrelid,
+        c.relation_id AS indrelid,
+        COUNT(*)::smallint AS indnatts,
+        COUNT(*)::smallint AS indnkeyatts,
+        true AS indisunique,
+        ARRAY_AGG(c.position)::smallint[] AS indkey,
+        ARRAY[]::smallint[] as indoption,
+        NULL AS indexprs,
+        NULL AS indpred,
+        TRUE AS indisprimary,
+        ARRAY[]::int[] AS indclass,
+        false AS indisexclusion,
+        true AS indimmediate,
+        false AS indisclustered,
+        true AS indisvalid,
+        false AS indcheckxmin,
+        true AS indisready,
+        true AS indislive,
+        false AS indisreplident
+    FROM rw_catalog.rw_columns c
+    WHERE c.is_primary_key = true AND c.is_hidden = false
+    AND c.relation_id IN (
+        SELECT id
+        FROM rw_catalog.rw_tables
+    )
+    GROUP BY c.relation_id"
 )]
 #[derive(Fields)]
 struct PgIndex {

src/frontend/src/catalog/system_catalog/pg_catalog/pg_indexes.rs

@@ -28,6 +28,19 @@ use risingwave_frontend_macro::system_catalog;
         FROM rw_catalog.rw_indexes i
         JOIN rw_catalog.rw_tables t ON i.primary_table_id = t.id
         JOIN rw_catalog.rw_schemas s ON i.schema_id = s.id
+    UNION ALL
+    SELECT s.name AS schemaname,
+            t.name AS tablename,
+            concat(t.name, '_pkey') AS indexname,
+            NULL AS tablespace,
+            '' AS indexdef
+        FROM rw_catalog.rw_tables t
+        JOIN rw_catalog.rw_schemas s ON t.schema_id = s.id
+        WHERE t.id IN (
+            SELECT DISTINCT relation_id
+            FROM rw_catalog.rw_columns
+            WHERE is_primary_key = true AND is_hidden = false
+        )
     "
 )]
 #[derive(Fields)]