Merge pull request mariadb-corporation#2837 from tntnatbry/MCOL-5357-dev

MCOL-5357 Fix TPC-DS query error "MCS-3009: Unknown column '.<colname>'".

Author: drrtuy

dbcon/mysql/ha_mcs_execplan.cpp

@@ -2454,6 +2454,20 @@ SimpleColumn* buildSimpleColFromDerivedTable(gp_walk_info& gwi, Item_field* ifp)
         SimpleColumn* col = dynamic_cast<SimpleColumn*>(cols[j].get());
         string alias = cols[j]->alias();
 
+        // MCOL-5357 For the following query:
+
+        // select item from (
+        // select item from (select a as item from t1) tt
+        // union all
+        // select item from (select a as item from t1) tt
+        // ) ttt;
+
+        // When the execution reaches the outermost item (ttt.item),
+        // alias = "`tt`.`item`" and ifp->field_name.str = "item".
+        // To make the execution enter the if block below, we strip off
+        // the backticks from alias.
+        boost::erase_all(alias, "`");
+
         if (strcasecmp(ifp->field_name.str, alias.c_str()) == 0 ||
             (col && alias.find(".") != string::npos &&
              (strcasecmp(ifp->field_name.str, col->columnName().c_str()) == 0 ||

mysql-test/columnstore/bugfixes/mcol-5357.result

@@ -0,0 +1,18 @@
+DROP DATABASE IF EXISTS mcol_5357;
+CREATE DATABASE mcol_5357;
+USE mcol_5357;
+CREATE TABLE t1 (a INT)engine=columnstore;
+INSERT INTO t1 VALUES (1), (2), (3);
+SELECT item FROM (
+SELECT item FROM (SELECT a AS item FROM t1) tt
+UNION ALL
+SELECT item FROM (SELECT a AS item FROM t1) tt
+) ttt;
+item
+1
+2
+3
+1
+2
+3
+DROP DATABASE mcol_5357;

mysql-test/columnstore/bugfixes/mcol-5357.test

@@ -0,0 +1,24 @@
+#
+# MCOL-5357 Fix TPC-DS query error "MCS-3009: Unknown column '.<colname>'"
+#
+
+--source ../include/have_columnstore.inc
+
+--disable_warnings
+DROP DATABASE IF EXISTS mcol_5357;
+--enable_warnings
+CREATE DATABASE mcol_5357;
+USE mcol_5357;
+
+CREATE TABLE t1 (a INT)engine=columnstore;
+INSERT INTO t1 VALUES (1), (2), (3);
+
+SELECT item FROM (
+SELECT item FROM (SELECT a AS item FROM t1) tt
+UNION ALL
+SELECT item FROM (SELECT a AS item FROM t1) tt
+) ttt;
+
+--disable_warnings
+DROP DATABASE mcol_5357;
+--enable_warnings