ClickHouse/src/Functions/FunctionJoinGet.cpp

#include <Functions/FunctionJoinGet.h>

#include <Columns/ColumnString.h>
#include <Functions/FunctionFactory.h>
#include <Functions/FunctionHelpers.h>
#include <Interpreters/Context.h>
#include <Interpreters/HashJoin.h>
#include <Storages/StorageJoin.h>


namespace DB
{
namespace ErrorCodes
{
    extern const int ILLEGAL_TYPE_OF_ARGUMENT;
    extern const int NUMBER_OF_ARGUMENTS_DOESNT_MATCH;
}

template <bool or_null>
ColumnPtr ExecutableFunctionJoinGet<or_null>::execute(ColumnsWithTypeAndName & arguments, const DataTypePtr &, size_t)
{
    ColumnsWithTypeAndName keys;
    for (size_t i = 2; i < arguments.size(); ++i)
    {
        auto key = arguments[i];
        keys.emplace_back(std::move(key));
    }
    return join->joinGet(keys, result_columns).column;
}

template <bool or_null>
ExecutableFunctionImplPtr FunctionJoinGet<or_null>::prepare(const ColumnsWithTypeAndName &) const
{
    return std::make_unique<ExecutableFunctionJoinGet<or_null>>(join, DB::Block{{return_type->createColumn(), return_type, attr_name}});
}

static auto getJoin(const ColumnsWithTypeAndName & arguments, const Context & context)
{
    String join_name;
    if (const auto * name_col = checkAndGetColumnConst<ColumnString>(arguments[0].column.get()))
    {
        join_name = name_col->getValue<String>();
    }
    else
        throw Exception(
            "Illegal type " + arguments[0].type->getName() + " of first argument of function joinGet, expected a const string.",
            ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);

    size_t dot = join_name.find('.');
    String database_name;
    if (dot == String::npos)
    {
        database_name = context.getCurrentDatabase();
        dot = 0;
    }
    else
    {
        database_name = join_name.substr(0, dot);
        ++dot;
    }
    String table_name = join_name.substr(dot);
    if (table_name.empty())
        throw Exception("joinGet does not allow empty table name", ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
    auto table = DatabaseCatalog::instance().getTable({database_name, table_name}, context);
    auto storage_join = std::dynamic_pointer_cast<StorageJoin>(table);
    if (!storage_join)
        throw Exception("Table " + join_name + " should have engine StorageJoin", ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);

    String attr_name;
    if (const auto * name_col = checkAndGetColumnConst<ColumnString>(arguments[1].column.get()))
    {
        attr_name = name_col->getValue<String>();
    }
    else
        throw Exception(
            "Illegal type " + arguments[1].type->getName() + " of second argument of function joinGet, expected a const string.",
            ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT);
    return std::make_pair(storage_join, attr_name);
}

template <bool or_null>
FunctionBaseImplPtr JoinGetOverloadResolver<or_null>::build(const ColumnsWithTypeAndName & arguments, const DataTypePtr &) const
{
    if (arguments.size() < 3)
        throw Exception(
            "Number of arguments for function " + getName() + " doesn't match: passed " + toString(arguments.size())
                + ", should be greater or equal to 3",
            ErrorCodes::NUMBER_OF_ARGUMENTS_DOESNT_MATCH);
    auto [storage_join, attr_name] = getJoin(arguments, context);
    auto join = storage_join->getJoin();
    DataTypes data_types(arguments.size() - 2);
    for (size_t i = 2; i < arguments.size(); ++i)
        data_types[i - 2] = arguments[i].type;
    auto return_type = join->joinGetCheckAndGetReturnType(data_types, attr_name, or_null);
    auto table_lock = storage_join->lockForShare(context.getInitialQueryId(), context.getSettingsRef().lock_acquire_timeout);
    return std::make_unique<FunctionJoinGet<or_null>>(table_lock, storage_join, join, attr_name, data_types, return_type);
}

void registerFunctionJoinGet(FunctionFactory & factory)
{
    // joinGet
    factory.registerFunction<JoinGetOverloadResolver<false>>();
    // joinGetOrNull
    factory.registerFunction<JoinGetOverloadResolver<true>>();
}

template class ExecutableFunctionJoinGet<true>;
template class ExecutableFunctionJoinGet<false>;
template class FunctionJoinGet<true>;
template class FunctionJoinGet<false>;
template class JoinGetOverloadResolver<true>;
template class JoinGetOverloadResolver<false>;
}