blob: 6ec5ca7a9c10d3f866a61c434b22d7291e70b6b0 (
plain) (
blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
|
#include <Columns/getLeastSuperColumn.h>
#include <Columns/IColumn.h>
#include <Columns/ColumnConst.h>
#include <Common/assert_cast.h>
#include <DataTypes/getLeastSupertype.h>
namespace DB
{
namespace ErrorCodes
{
extern const int LOGICAL_ERROR;
}
static bool sameConstants(const IColumn & a, const IColumn & b)
{
return assert_cast<const ColumnConst &>(a).getField() == assert_cast<const ColumnConst &>(b).getField();
}
ColumnWithTypeAndName getLeastSuperColumn(const std::vector<const ColumnWithTypeAndName *> & columns)
{
if (columns.empty())
throw Exception(ErrorCodes::LOGICAL_ERROR, "Logical error: no src columns for supercolumn");
ColumnWithTypeAndName result = *columns[0];
/// Determine common type.
size_t num_const = 0;
DataTypes types(columns.size());
for (size_t i = 0; i < columns.size(); ++i)
{
types[i] = columns[i]->type;
if (isColumnConst(*columns[i]->column))
++num_const;
}
result.type = getLeastSupertype(types);
/// Create supertype column saving constness if possible.
bool save_constness = false;
if (columns.size() == num_const)
{
save_constness = true;
for (size_t i = 1; i < columns.size(); ++i)
{
const ColumnWithTypeAndName & first = *columns[0];
const ColumnWithTypeAndName & other = *columns[i];
if (!sameConstants(*first.column, *other.column))
{
save_constness = false;
break;
}
}
}
if (save_constness)
result.column = result.type->createColumnConst(0, assert_cast<const ColumnConst &>(*columns[0]->column).getField());
else
result.column = result.type->createColumn();
return result;
}
}
|
