#pragma once #include namespace DB { /** Combines several sources into one. * Unlike UnionBlockInputStream, it does this sequentially. * Blocks of different sources are not interleaved with each other. */ class ConcatBlockInputStream : public IProfilingBlockInputStream { public: ConcatBlockInputStream(BlockInputStreams inputs_) { children.insert(children.end(), inputs_.begin(), inputs_.end()); current_stream = children.begin(); } String getName() const override { return "Concat"; } Block getHeader() const override { return children.at(0)->getHeader(); } protected: Block readImpl() override { Block res; while (current_stream != children.end()) { res = (*current_stream)->read(); if (res) break; else { (*current_stream)->readSuffix(); ++current_stream; } } return res; } private: BlockInputStreams::iterator current_stream; }; }