From f0a5857da8c43d3ef93e13114bc14cffb3e65f6a Mon Sep 17 00:00:00 2001
From: syj <904673462@qq.com>
Date: Wed, 21 Oct 2020 20:11:19 +0800
Subject: [PATCH] Fixed syntax error when 'IF EXISTS' is used in 'ALTER POLICY
 [IF EXISTS] old_name ON table_a RENAME TO new_name'

---
 src/common/backend/parser/gram.y              | 20 ++++++++++++++
 .../optimizer/commands/sec_rls_cmds.cpp       | 27 ++++++++++++-------
 .../regress/expected/rowlevelsecurity.out     |  4 +++
 src/test/regress/sql/rowlevelsecurity.sql     |  2 ++
 4 files changed, 43 insertions(+), 10 deletions(-)

diff --git a/src/common/backend/parser/gram.y b/src/common/backend/parser/gram.y
index b86c8bb92..5a563d1df 100755
--- a/src/common/backend/parser/gram.y
+++ b/src/common/backend/parser/gram.y
@@ -10213,6 +10213,26 @@ RenameStmt: ALTER AGGREGATE func_name aggr_args RENAME TO name
 					n->missing_ok = false;
 					$$ = (Node *)n;
 				}
+			| ALTER POLICY IF_P EXISTS name ON qualified_name RENAME TO name
+				{
+					RenameStmt *n = makeNode(RenameStmt);
+					n->renameType = OBJECT_RLSPOLICY;
+					n->subname = $5;
+					n->relation = $7;
+					n->newname = $10;
+					n->missing_ok = true;
+					$$ = (Node *)n;
+				}
+			| ALTER ROW LEVEL SECURITY POLICY IF_P EXISTS name ON qualified_name RENAME TO name
+				{
+					RenameStmt *n = makeNode(RenameStmt);
+					n->renameType = OBJECT_RLSPOLICY;
+					n->subname = $8;
+					n->relation = $10;
+					n->newname = $13;
+					n->missing_ok = true;
+					$$ = (Node *)n;
+				}
 			| ALTER SCHEMA name RENAME TO name
 				{
 					RenameStmt *n = makeNode(RenameStmt);
diff --git a/src/gausskernel/optimizer/commands/sec_rls_cmds.cpp b/src/gausskernel/optimizer/commands/sec_rls_cmds.cpp
index 86089d702..8e4079ae0 100755
--- a/src/gausskernel/optimizer/commands/sec_rls_cmds.cpp
+++ b/src/gausskernel/optimizer/commands/sec_rls_cmds.cpp
@@ -513,20 +513,27 @@ void RenameRlsPolicy(RenameStmt* renameStmt)
     rlsPolicyTuple = systable_getnext(scanDesc);
     /* Policy does not exists */
     if (HeapTupleIsValid(rlsPolicyTuple) == false) {
-        ereport(ERROR,
-            (errcode(ERRCODE_UNDEFINED_OBJECT),
-                errmsg("row level security policy \"%s\" for relation \"%s\" does not exists",
+        if (renameStmt->missing_ok) {
+            ereport(NOTICE, 
+                (errmsg("row level security policy \"%s\" for relation \"%s\" does not exist, skipping",
                     renameStmt->subname,
                     renameStmt->relation->relname)));
+        } else {
+            ereport(ERROR,
+                (errcode(ERRCODE_UNDEFINED_OBJECT),
+                    errmsg("row level security policy \"%s\" for relation \"%s\" does not exist",
+                        renameStmt->subname,
+                        renameStmt->relation->relname)));
+        }
+    } else {
+        /* Copy tuple here, because of update index later */
+        rlsPolicyTuple = heap_copytuple(rlsPolicyTuple);
+        /* Update RLS policy name */
+        (void)namestrcpy(&(((Form_pg_rlspolicy)GETSTRUCT(rlsPolicyTuple))->polname), renameStmt->newname);
+        simple_heap_update(pg_rlspolicy, &rlsPolicyTuple->t_self, rlsPolicyTuple);
+        CatalogUpdateIndexes(pg_rlspolicy, rlsPolicyTuple);
     }
 
-    /* Copy tuple here, because of update index later */
-    rlsPolicyTuple = heap_copytuple(rlsPolicyTuple);
-    /* Update RLS policy name */
-    (void)namestrcpy(&(((Form_pg_rlspolicy)GETSTRUCT(rlsPolicyTuple))->polname), renameStmt->newname);
-    simple_heap_update(pg_rlspolicy, &rlsPolicyTuple->t_self, rlsPolicyTuple);
-    CatalogUpdateIndexes(pg_rlspolicy, rlsPolicyTuple);
-
     /*
      * Invalidate relation's relcache entry so that other backends (and this
      * one too!) are sent SI message to make them rebuild relcache entries.
diff --git a/src/test/regress/expected/rowlevelsecurity.out b/src/test/regress/expected/rowlevelsecurity.out
index 559192e55..e9b050b26 100644
--- a/src/test/regress/expected/rowlevelsecurity.out
+++ b/src/test/regress/expected/rowlevelsecurity.out
@@ -815,7 +815,11 @@ select * from pg_shdepend where classid = 3254 and refclassid = 1260 and refobji
 DROP USER regress_rls_bob;
 ALTER POLICY p01 ON document_row USING (dauthor = current_user);
 ALTER POLICY p01 ON document_row RENAME TO p12;
+ALTER POLICY IF EXISTS p01 on document_row RENAME to p13;
+NOTICE:  row level security policy "p01" for relation "document_row" does not exist, skipping
 ALTER POLICY p12 ON document_row RENAME TO p13;
+ALTER ROW LEVEL SECURITY POLICY IF EXISTS p12 ON document_row RENAME TO p01;
+NOTICE:  row level security policy "p12" for relation "document_row" does not exist, skipping
 ALTER POLICY p13 ON document_row RENAME TO p01;
 SELECT * FROM pg_rlspolicies ORDER BY tablename, policyname;
      schemaname     |  tablename   |    policyname    | policypermissive |     policyroles      | policycmd |                                                 policyqual                                                 
diff --git a/src/test/regress/sql/rowlevelsecurity.sql b/src/test/regress/sql/rowlevelsecurity.sql
index 5e80f561b..d8c7c25d6 100644
--- a/src/test/regress/sql/rowlevelsecurity.sql
+++ b/src/test/regress/sql/rowlevelsecurity.sql
@@ -331,7 +331,9 @@ select * from pg_shdepend where classid = 3254 and refclassid = 1260 and refobji
 DROP USER regress_rls_bob;
 ALTER POLICY p01 ON document_row USING (dauthor = current_user);
 ALTER POLICY p01 ON document_row RENAME TO p12;
+ALTER POLICY IF EXISTS p01 on document_row RENAME to p13;
 ALTER POLICY p12 ON document_row RENAME TO p13;
+ALTER ROW LEVEL SECURITY POLICY IF EXISTS p12 ON document_row RENAME TO p01;
 ALTER POLICY p13 ON document_row RENAME TO p01;
 SELECT * FROM pg_rlspolicies ORDER BY tablename, policyname;
 -- enable private object