Fix JOIN over LC and Nullable in key (#11414)

src/Interpreters/ActionsVisitor.cpp

@@ -512,7 +512,8 @@ void ActionsMatcher::visit(const ASTFunction & node, const ASTPtr & ast, Data &
                 if (data.only_consts)
                     arguments_present = false;
                 else
-                    throw Exception("Unknown identifier: " + child_column_name, ErrorCodes::UNKNOWN_IDENTIFIER);
+                    throw Exception("Unknown identifier: " + child_column_name + " there are columns: " + data.getSampleBlock().dumpNames(),
+                                    ErrorCodes::UNKNOWN_IDENTIFIER);
             }
         }
     }

src/Interpreters/HashJoin.cpp

@@ -107,7 +107,7 @@ static ColumnWithTypeAndName correctNullability(ColumnWithTypeAndName && column,
 {
     if (nullable)
     {
-        JoinCommon::convertColumnToNullable(column);
+        JoinCommon::convertColumnToNullable(column, true);
         if (column.type->isNullable() && !negative_null_map.empty())
         {
             MutableColumnPtr mutable_column = IColumn::mutate(std::move(column.column));

src/Interpreters/join_common.cpp

@@ -16,8 +16,14 @@ namespace ErrorCodes
 namespace JoinCommon
 {
 
-void convertColumnToNullable(ColumnWithTypeAndName & column)
+void convertColumnToNullable(ColumnWithTypeAndName & column, bool low_card_nullability)
 {
+    if (low_card_nullability && column.type->lowCardinality())
+    {
+        column.column = recursiveRemoveLowCardinality(column.column);
+        column.type = recursiveRemoveLowCardinality(column.type);
+    }
+
     if (column.type->isNullable() || !column.type->canBeInsideNullable())
         return;
 

src/Interpreters/join_common.h

@@ -13,7 +13,7 @@ using ColumnRawPtrs = std::vector<const IColumn *>;
 namespace JoinCommon
 {
 
-void convertColumnToNullable(ColumnWithTypeAndName & column);
+void convertColumnToNullable(ColumnWithTypeAndName & column, bool low_card_nullability = false);
 void convertColumnsToNullable(Block & block, size_t starting_pos = 0);
 void removeColumnNullability(ColumnWithTypeAndName & column);
 Columns materializeColumns(const Block & block, const Names & names);

tests/queries/0_stateless/01142_join_lc_and_nullable_in_key.reference

@@ -0,0 +1,29 @@
+1	l	\N	Nullable(String)
+2		\N	Nullable(String)
+1	l	\N	Nullable(String)
+2		\N	Nullable(String)
+-
+1	l	\N	Nullable(String)
+0		\N	Nullable(String)
+0		\N	Nullable(String)
+1	l	\N	Nullable(String)
+-
+1	l	\N	Nullable(String)
+0		\N	Nullable(String)
+0		\N	Nullable(String)
+1	l	\N	Nullable(String)
+-
+1	l	\N	Nullable(String)
+2		\N	Nullable(String)
+1	l	\N	Nullable(String)
+2		\N	Nullable(String)
+-
+1	l	\N	Nullable(String)
+\N		\N	Nullable(String)
+1	l	\N	Nullable(String)
+\N		\N	Nullable(String)
+-
+1	l	\N	Nullable(String)
+\N		\N	Nullable(String)
+1	l	\N	Nullable(String)
+\N		\N	Nullable(String)

tests/queries/0_stateless/01142_join_lc_and_nullable_in_key.sql

@@ -0,0 +1,50 @@
+DROP TABLE IF EXISTS t;
+DROP TABLE IF EXISTS nr;
+
+CREATE TABLE t (`x` UInt32, `lc` LowCardinality(String)) ENGINE = Memory;
+CREATE TABLE nr (`x` Nullable(UInt32), `lc` Nullable(String)) ENGINE = Memory;
+
+INSERT INTO t VALUES (1, 'l');
+INSERT INTO nr VALUES (2, NULL);
+
+SET join_use_nulls = 0;
+
+SELECT x, lc, r.lc, toTypeName(r.lc) FROM t AS l LEFT JOIN nr AS r USING (x) ORDER BY x;
+SELECT x, lc, r.lc, toTypeName(r.lc) FROM t AS l RIGHT JOIN nr AS r USING (x) ORDER BY x;
+SELECT x, lc, r.lc, toTypeName(r.lc) FROM t AS l FULL JOIN nr AS r USING (x) ORDER BY x;
+
+SELECT '-';
+
+SELECT x, lc, r.lc, toTypeName(r.lc) FROM t AS l LEFT JOIN nr AS r USING (lc) ORDER BY x;
+SELECT x, lc, r.lc, toTypeName(r.lc) FROM t AS l RIGHT JOIN nr AS r USING (lc) ORDER BY x;
+SELECT x, lc, r.lc, toTypeName(r.lc) FROM t AS l FULL JOIN nr AS r USING (lc) ORDER BY x;
+
+SELECT '-';
+
+SELECT x, lc, materialize(r.lc) y, toTypeName(y) FROM t AS l LEFT JOIN nr AS r USING (lc) ORDER BY x;
+SELECT x, lc, materialize(r.lc) y, toTypeName(y) FROM t AS l RIGHT JOIN nr AS r USING (lc) ORDER BY x;
+SELECT x, lc, materialize(r.lc) y, toTypeName(y) FROM t AS l FULL JOIN nr AS r USING (lc) ORDER BY x;
+
+SELECT '-';
+
+SET join_use_nulls = 1;
+
+SELECT x, lc, r.lc, toTypeName(r.lc) FROM t AS l LEFT JOIN nr AS r USING (x) ORDER BY x;
+SELECT x, lc, r.lc, toTypeName(r.lc) FROM t AS l RIGHT JOIN nr AS r USING (x) ORDER BY x;
+SELECT x, lc, r.lc, toTypeName(r.lc) FROM t AS l FULL JOIN nr AS r USING (x) ORDER BY x;
+
+SELECT '-';
+
+SELECT x, lc, r.lc, toTypeName(r.lc) FROM t AS l LEFT JOIN nr AS r USING (lc) ORDER BY x;
+SELECT x, lc, r.lc, toTypeName(r.lc) FROM t AS l RIGHT JOIN nr AS r USING (lc) ORDER BY x;
+SELECT x, lc, r.lc, toTypeName(r.lc) FROM t AS l FULL JOIN nr AS r USING (lc) ORDER BY x;
+
+SELECT '-';
+
+SELECT x, lc, materialize(r.lc) y, toTypeName(y) FROM t AS l LEFT JOIN nr AS r USING (lc) ORDER BY x;
+SELECT x, lc, materialize(r.lc) y, toTypeName(y) FROM t AS l RIGHT JOIN nr AS r USING (lc) ORDER BY x;
+SELECT x, lc, materialize(r.lc) y, toTypeName(y) FROM t AS l FULL JOIN nr AS r USING (lc) ORDER BY x;
+
+
+DROP TABLE t;
+DROP TABLE nr;