Merge pull request #7908 from CurtizJ/enum_conversion

Fix enum conversion in native format for backward compatibility.

dbms/src/DataStreams/NativeBlockInputStream.cpp

@@ -159,7 +159,7 @@ Block NativeBlockInputStream::readImpl()
             auto & header_column = header.getByName(column.name);
             if (!header_column.type->equals(*column.type))
             {
-                column.column = recursiveLowCardinalityConversion(column.column, column.type, header.getByPosition(i).type);
+                column.column = recursiveTypeConversion(column.column, column.type, header.getByPosition(i).type);
                 column.type = header.getByPosition(i).type;
             }
         }

dbms/src/DataTypes/DataTypeLowCardinality.h

@@ -126,6 +126,6 @@ DataTypePtr recursiveRemoveLowCardinality(const DataTypePtr & type);
 ColumnPtr recursiveRemoveLowCardinality(const ColumnPtr & column);
 
 /// Convert column of type from_type to type to_type by converting nested LowCardinality columns.
-ColumnPtr recursiveLowCardinalityConversion(const ColumnPtr & column, const DataTypePtr & from_type, const DataTypePtr & to_type);
+ColumnPtr recursiveTypeConversion(const ColumnPtr & column, const DataTypePtr & from_type, const DataTypePtr & to_type);
 
 }

dbms/src/DataTypes/DataTypeLowCardinalityHelpers.cpp

@@ -84,7 +84,7 @@ ColumnPtr recursiveRemoveLowCardinality(const ColumnPtr & column)
     return column;
 }
 
-ColumnPtr recursiveLowCardinalityConversion(const ColumnPtr & column, const DataTypePtr & from_type, const DataTypePtr & to_type)
+ColumnPtr recursiveTypeConversion(const ColumnPtr & column, const DataTypePtr & from_type, const DataTypePtr & to_type)
 {
     if (!column)
         return column;
@@ -92,10 +92,14 @@ ColumnPtr recursiveLowCardinalityConversion(const ColumnPtr & column, const Data
     if (from_type->equals(*to_type))
         return column;
 
+    /// We can allow insert enum column if it's numeric type is the same as the column's type in table.
+    if (WhichDataType(to_type).isEnum() && from_type->getTypeId() == to_type->getTypeId())
+        return column;
+
     if (const auto * column_const = typeid_cast<const ColumnConst *>(column.get()))
     {
         auto & nested = column_const->getDataColumnPtr();
-        auto nested_no_lc = recursiveLowCardinalityConversion(nested, from_type, to_type);
+        auto nested_no_lc = recursiveTypeConversion(nested, from_type, to_type);
         if (nested.get() == nested_no_lc.get())
             return column;
 
@@ -131,7 +135,7 @@ ColumnPtr recursiveLowCardinalityConversion(const ColumnPtr & column, const Data
             auto & nested_to = to_array_type->getNestedType();
 
             return ColumnArray::create(
-                    recursiveLowCardinalityConversion(column_array->getDataPtr(), nested_from, nested_to),
+                    recursiveTypeConversion(column_array->getDataPtr(), nested_from, nested_to),
                     column_array->getOffsetsPtr());
         }
     }
@@ -154,7 +158,7 @@ ColumnPtr recursiveLowCardinalityConversion(const ColumnPtr & column, const Data
             for (size_t i = 0; i < columns.size(); ++i)
             {
                 auto & element = columns[i];
-                auto element_no_lc = recursiveLowCardinalityConversion(element, from_elements.at(i), to_elements.at(i));
+                auto element_no_lc = recursiveTypeConversion(element, from_elements.at(i), to_elements.at(i));
                 if (element.get() != element_no_lc.get())
                 {
                     element = element_no_lc;

dbms/tests/queries/0_stateless/01035_enum_conversion_native_format.reference

+a
+a

dbms/tests/queries/0_stateless/01035_enum_conversion_native_format.sh

+#!/usr/bin/env bash
+
+CURDIR=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
+. $CURDIR/../shell_config.sh
+
+set -e
+
+${CLICKHOUSE_CLIENT} --query="drop table if exists enum_source;"
+${CLICKHOUSE_CLIENT} --query="drop table if exists enum_buf;"
+
+${CLICKHOUSE_CLIENT} --query="create table enum_source(e Enum8('a'=1)) engine = MergeTree order by tuple()"
+${CLICKHOUSE_CLIENT} --query="insert into enum_source values ('a')"
+${CLICKHOUSE_CLIENT} --query="create table enum_buf engine = Log as select * from enum_source;"
+${CLICKHOUSE_CLIENT} --query="alter table enum_source modify column e Enum8('a'=1, 'b'=2);"
+
+${CLICKHOUSE_CLIENT} --query="select * from enum_buf format Native" \
+    | ${CLICKHOUSE_CLIENT} --query="insert into enum_source format Native"
+
+${CLICKHOUSE_CLIENT} --query="select * from enum_source;"
+
+${CLICKHOUSE_CLIENT} --query="drop table enum_source;"
+${CLICKHOUSE_CLIENT} --query="drop table enum_buf;"