void DescribeStreamFactory::createForShard(
const Cluster::ShardInfo & shard_info,
const String & query, const ASTPtr & query_ast,
const Context & context, const ThrottlerPtr & throttler,
BlockInputStreams & res)
{
for (const Cluster::Address & local_address : shard_info.local_addresses)
{
InterpreterDescribeQuery interpreter{query_ast, context};
BlockInputStreamPtr stream = interpreter.execute().in;
/** Materialization is needed, since from remote servers the constants come materialized.
* If you do not do this, different types (Const and non-Const) columns will be produced in different threads,
* And this is not allowed, since all code is based on the assumption that in the block stream all types are the same.
*/
BlockInputStreamPtr materialized_stream = std::make_shared<MaterializingBlockInputStream>(stream);
res.emplace_back(std::make_shared<BlockExtraInfoInputStream>(materialized_stream, toBlockExtraInfo(local_address)));
}
auto remote_stream = std::make_shared<RemoteBlockInputStream>(
shard_info.pool, query, context, nullptr, throttler);
remote_stream->setPoolMode(PoolMode::GET_ALL);
remote_stream->appendExtraInfo();
res.emplace_back(std::move(remote_stream));
}
BlockInputStreamPtr DescribeQueryConstructor::createRemote(
ConnectionPoolWithFailoverPtrs && pools, const std::string & query,
const Settings & settings, ThrottlerPtr throttler, const Context & context)
{
auto stream = std::make_shared<RemoteBlockInputStream>(std::move(pools), query, &settings, context, throttler);
stream->setPoolMode(pool_mode);
stream->appendExtraInfo();
return stream;
}