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
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
|
#include <Functions/IFunction.h>
#include <Functions/FunctionFactory.h>
#include <Interpreters/Context.h>
#include <DataTypes/DataTypeArray.h>
#include <DataTypes/DataTypeString.h>
namespace DB
{
namespace ErrorCodes
{
extern const int ILLEGAL_TYPE_OF_ARGUMENT;
}
namespace
{
class FunctionCurrentSchemas : public IFunction
{
const String db_name;
public:
static constexpr auto name = "currentSchemas";
static FunctionPtr create(ContextPtr context)
{
return std::make_shared<FunctionCurrentSchemas>(context->getCurrentDatabase());
}
explicit FunctionCurrentSchemas(const String & db_name_) :
db_name{db_name_}
{
}
String getName() const override
{
return name;
}
size_t getNumberOfArguments() const override
{
return 1;
}
DataTypePtr getReturnTypeImpl(const DataTypes & arguments) const override
{
// For compatibility, function implements the same signature as Postgres'
const bool argument_is_valid = arguments.size() == 1 && isBool(arguments.front());
if (!argument_is_valid)
throw Exception(ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT, "Argument for function {} must be bool", getName());
return std::make_shared<DataTypeArray>(std::make_shared<DataTypeString>());
}
bool isDeterministic() const override { return false; }
bool isSuitableForShortCircuitArgumentsExecution(const DataTypesWithConstInfo & /*arguments*/) const override { return false; }
ColumnPtr executeImpl(const ColumnsWithTypeAndName &, const DataTypePtr &, size_t input_rows_count) const override
{
return DataTypeArray(std::make_shared<DataTypeString>())
.createColumnConst(input_rows_count, Array { db_name });
}
};
}
REGISTER_FUNCTION(CurrentSchema)
{
factory.registerFunction<FunctionCurrentSchemas>(FunctionDocumentation
{
.description=R"(
Returns a single-element array with the name of the current database
Requires a boolean parameter, but it is ignored actually. It is required just for compatibility with the implementation of this function in other DB engines.
[example:common]
)",
.examples{
{"common", "SELECT current_schemas(true);", "['default']"}
}
},
FunctionFactory::CaseInsensitive);
factory.registerAlias("current_schemas", FunctionCurrentSchemas::name, FunctionFactory::CaseInsensitive);
}
}
|
