Support rename table without keyword TABLE

docs/en/sql-reference/statements/rename.md

@@ -16,7 +16,7 @@ The `RENAME` query is supported by the [Atomic](../../engines/database-engines/a
 **Syntax**
 
 ```sql
-RENAME DATABASE|TABLE|DICTIONARY name TO new_name [,...] [ON CLUSTER cluster]
+RENAME [DATABASE|TABLE|DICTIONARY] name TO new_name [,...] [ON CLUSTER cluster]
 ```
 
 ## RENAME DATABASE
@@ -48,6 +48,11 @@ RENAME TABLE [db1.]name1 TO [db2.]name2 [,...] [ON CLUSTER cluster]
 RENAME TABLE table_A TO table_A_bak, table_B TO table_B_bak;
 ```
 
+And you can use a simpler sql:  
+```sql
+RENAME table_A TO table_A_bak, table_B TO table_B_bak;
+```
+
 ## RENAME DICTIONARY
 
 Renames one or several dictionaries. This query can be used to move dictionaries between databases.

src/Parsers/ParserRenameQuery.cpp

@@ -11,6 +11,7 @@ namespace DB
 
 bool ParserRenameQuery::parseImpl(Pos & pos, ASTPtr & node, Expected & expected)
 {
+    ParserKeyword s_rename("RENAME");
     ParserKeyword s_rename_table("RENAME TABLE");
     ParserKeyword s_exchange_tables("EXCHANGE TABLES");
     ParserKeyword s_rename_dictionary("RENAME DICTIONARY");
@@ -24,18 +25,7 @@ bool ParserRenameQuery::parseImpl(Pos & pos, ASTPtr & node, Expected & expected)
     bool exchange = false;
     bool dictionary = false;
 
-    if (s_rename_table.ignore(pos, expected))
-        ;
-    else if (s_exchange_tables.ignore(pos, expected))
-        exchange = true;
-    else if (s_rename_dictionary.ignore(pos, expected))
-        dictionary = true;
-    else if (s_exchange_dictionaries.ignore(pos, expected))
-    {
-        exchange = true;
-        dictionary = true;
-    }
-    else if (s_rename_database.ignore(pos, expected))
+    if (s_rename_database.ignore(pos, expected))
     {
         ASTPtr from_db;
         ASTPtr to_db;
@@ -67,6 +57,19 @@ bool ParserRenameQuery::parseImpl(Pos & pos, ASTPtr & node, Expected & expected)
         node = query;
         return true;
     }
+    else if (s_rename_table.ignore(pos, expected))
+        ;
+    else if (s_exchange_tables.ignore(pos, expected))
+        exchange = true;
+    else if (s_rename_dictionary.ignore(pos, expected))
+        dictionary = true;
+    else if (s_exchange_dictionaries.ignore(pos, expected))
+    {
+        exchange = true;
+        dictionary = true;
+    }
+    else if (s_rename.ignore(pos, expected))
+        ;
     else
         return false;
 

tests/queries/0_stateless/02891_rename_table_without_keyword.reference

@@ -0,0 +1,7 @@
+r1
+r1_bak
+r1
+r1_bak
+r2_bak
+test_dictionary
+test_dictionary_2

tests/queries/0_stateless/02891_rename_table_without_keyword.sql

@@ -0,0 +1,42 @@
+DROP DATABASE IF EXISTS {CLICKHOUSE_DATABASE:Identifier};
+CREATE DATABASE IF NOT EXISTS {CLICKHOUSE_DATABASE:Identifier};
+
+CREATE TABLE IF NOT EXISTS {CLICKHOUSE_DATABASE:Identifier}.r1 (name String) Engine=Memory();
+SHOW TABLES FROM {CLICKHOUSE_DATABASE:Identifier};
+
+RENAME TABLE {CLICKHOUSE_DATABASE:Identifier}.r1 TO {CLICKHOUSE_DATABASE:Identifier}.r1_bak;
+SHOW TABLES FROM {CLICKHOUSE_DATABASE:Identifier};
+
+RENAME {CLICKHOUSE_DATABASE:Identifier}.r1_bak TO {CLICKHOUSE_DATABASE:Identifier}.r1;
+SHOW TABLES FROM {CLICKHOUSE_DATABASE:Identifier};
+
+CREATE TABLE IF NOT EXISTS {CLICKHOUSE_DATABASE:Identifier}.r2 (name String) Engine=Memory();
+RENAME {CLICKHOUSE_DATABASE:Identifier}.r1 TO {CLICKHOUSE_DATABASE:Identifier}.r1_bak,
+       {CLICKHOUSE_DATABASE:Identifier}.r2 TO {CLICKHOUSE_DATABASE:Identifier}.r2_bak;
+SHOW TABLES FROM {CLICKHOUSE_DATABASE:Identifier};
+
+CREATE TABLE IF NOT EXISTS {CLICKHOUSE_DATABASE:Identifier}.source_table (
+                id UInt64,
+                value String
+            ) ENGINE = Memory;
+
+CREATE DICTIONARY IF NOT EXISTS {CLICKHOUSE_DATABASE:Identifier}.test_dictionary
+(
+    id UInt64,
+    value String
+)
+PRIMARY KEY id
+SOURCE(CLICKHOUSE(TABLE '{CLICKHOUSE_DATABASE:String}.dictionary_table'))
+LAYOUT(FLAT())
+LIFETIME(MIN 0 MAX 1000);
+
+SHOW DICTIONARIES FROM {CLICKHOUSE_DATABASE:Identifier};
+
+RENAME {CLICKHOUSE_DATABASE:Identifier}.test_dictionary TO {CLICKHOUSE_DATABASE:Identifier}.test_dictionary_2;
+SHOW DICTIONARIES FROM {CLICKHOUSE_DATABASE:Identifier};
+
+SHOW DATABASES LIKE '{CLICKHOUSE_DATABASE:String}';
+RENAME {CLICKHOUSE_DATABASE:Identifier} TO {CLICKHOUSE_DATABASE_1:Identifier}; -- { serverError UNKNOWN_TABLE }
+SHOW DATABASES LIKE '{CLICKHOUSE_DATABASE:String}';
+
+DROP DATABASE IF EXISTS {CLICKHOUSE_DATABASE:Identifier};