Merge branch 'amosbird-master'

dbms/src/Interpreters/InterpreterDropQuery.cpp

@@ -121,18 +121,29 @@ BlockIO InterpreterDropQuery::executeToTemporaryTable(String & table_name, ASTDr
 {
     if (kind == ASTDropQuery::Kind::Detach)
         throw Exception("Unable to detach temporary table.", ErrorCodes::SYNTAX_ERROR);
-    else if (kind == ASTDropQuery::Kind::Drop)
+    else
     {
-        StoragePtr table = (context.hasSessionContext() ? context.getSessionContext() : context).tryRemoveExternalTable(table_name);
+        auto & context_handle = context.hasSessionContext() ? context.getSessionContext() : context;
+        StoragePtr table = context_handle.tryGetExternalTable(table_name);
         if (table)
         {
-            table->shutdown();
-            /// If table was already dropped by anyone, an exception will be thrown
-            auto table_lock = table->lockForAlter(__PRETTY_FUNCTION__);
-            /// Delete table data
-            table->drop();
-            table->is_dropped = true;
-            return {};
+            if (kind == ASTDropQuery::Kind::Truncate)
+            {
+                /// If table was already dropped by anyone, an exception will be thrown
+                auto table_lock = table->lockDataForAlter(__PRETTY_FUNCTION__);
+                /// Drop table data, don't touch metadata
+                table->truncate(query_ptr);
+            }
+            else if (kind == ASTDropQuery::Kind::Drop)
+            {
+                context_handle.tryRemoveExternalTable(table_name);
+                table->shutdown();
+                /// If table was already dropped by anyone, an exception will be thrown
+                auto table_lock = table->lockForAlter(__PRETTY_FUNCTION__);
+                /// Delete table data
+                table->drop();
+                table->is_dropped = true;
+            }
         }
     }
 

dbms/src/Parsers/ASTDropQuery.cpp

@@ -53,6 +53,9 @@ void ASTDropQuery::formatQueryImpl(const FormatSettings & settings, FormatState
     else
         throw Exception("Not supported kind of drop query.", ErrorCodes::SYNTAX_ERROR);
 
+    if (temporary)
+        settings.ostr << "TEMPORARY ";
+
     settings.ostr << ((table.empty() && !database.empty()) ? "DATABASE " : "TABLE ");
 
     if (if_exists)

dbms/tests/queries/0_stateless/00670_truncate_temporary_table.reference

+======Before Truncate======
+0
+======After Truncate And Empty======
+======After Truncate And Insert Data======
+0

dbms/tests/queries/0_stateless/00670_truncate_temporary_table.sql

+drop temporary table if exists test;
+create temporary table test(id int);
+
+select '======Before Truncate======';
+insert into test values(0);
+select * from test;
+
+select '======After Truncate And Empty======';
+truncate temporary table test;
+select * from test;
+
+select '======After Truncate And Insert Data======';
+insert into test values(0);
+select * from test;
+
+drop temporary table test;