void PushingToViewsBlockOutputStream::process(const Block & block, size_t view_num)
{
auto & view = views[view_num];
try
{
BlockInputStreamPtr from = std::make_shared<OneBlockInputStream>(block);
InterpreterSelectQuery select(view.query, *views_context, from);
BlockInputStreamPtr in = std::make_shared<MaterializingBlockInputStream>(select.execute().in);
/// Squashing is needed here because the materialized view query can generate a lot of blocks
/// even when only one block is inserted into the parent table (e.g. if the query is a GROUP BY
/// and two-level aggregation is triggered).
in = std::make_shared<SquashingBlockInputStream>(
in, context.getSettingsRef().min_insert_block_size_rows, context.getSettingsRef().min_insert_block_size_bytes);
in->readPrefix();
while (Block result_block = in->read())
{
Nested::validateArraySizes(result_block);
view.out->write(result_block);
}
in->readSuffix();
}
catch (Exception & ex)
{
ex.addMessage("while pushing to view " + backQuoteIfNeed(view.database) + "." + backQuoteIfNeed(view.table));
throw;
}
}
NamesAndTypesList getStructureOfRemoteTable(
const Cluster & cluster,
const std::string & database,
const std::string & table,
const Context & context)
{
/// Запрос на описание таблицы
String query = "DESC TABLE " + backQuoteIfNeed(database) + "." + backQuoteIfNeed(table);
Settings settings = context.getSettings();
NamesAndTypesList res;
/// Отправляем на первый попавшийся удалённый шард.
const auto & shard_info = cluster.getAnyShardInfo();
if (shard_info.isLocal())
return context.getTable(database, table)->getColumnsList();
ConnectionPoolPtr pool = shard_info.pool;
BlockInputStreamPtr input =
std::make_shared<RemoteBlockInputStream>(
pool.get(), query, &settings, nullptr,
Tables(), QueryProcessingStage::Complete, context);
input->readPrefix();
const DataTypeFactory & data_type_factory = DataTypeFactory::instance();
while (Block current = input->read())
{
ColumnPtr name = current.getByName("name").column;
ColumnPtr type = current.getByName("type").column;
size_t size = name->size();
for (size_t i = 0; i < size; ++i)
{
String column_name = (*name)[i].get<const String &>();
String data_type_name = (*type)[i].get<const String &>();
res.emplace_back(column_name, data_type_factory.get(data_type_name));
}
}
return res;
}