dbms: allow use of clickhouse as a dictionary source [#METR-13298]

dbms/include/DB/Dictionaries/ClickhouseDictionarySource.h

@@ -0,0 +1,109 @@
+#pragma once
+
+#include <DB/Interpreters/Context.h>
+#include <DB/Dictionaries/IDictionarySource.h>
+#include <DB/Client/ConnectionPool.h>
+#include <statdaemons/ext/range.hpp>
+#include <Poco/Util/AbstractConfiguration.h>
+#include <DB/DataStreams/RemoteBlockInputStream.h>
+#include <DB/Interpreters/InterpreterSelectQuery.h>
+#include <DB/Interpreters/executeQuery.h>
+#include <Poco/Net/NetworkInterface.h>
+
+namespace DB
+{
+
+class ClickhouseDictionarySource final : public IDictionarySource
+{
+	static const auto max_block_size = 8192;
+	static const auto max_connections = 1;
+
+public:
+	ClickhouseDictionarySource(Poco::Util::AbstractConfiguration & config, const std::string & config_prefix,
+		Block & sample_block, const Context & context)
+		: host{config.getString(config_prefix + "host")},
+		  port(config.getInt(config_prefix + "port")),
+		  is_local{isLocal(host, port)},
+		  pool{is_local ? nullptr : ext::make_unique<ConnectionPool>(
+			max_connections, host, port,
+			config.getString(config_prefix + "db", ""),
+			config.getString(config_prefix + "user", ""),
+			config.getString(config_prefix + "password", ""),
+			context.getDataTypeFactory(),
+			"ClickhouseDictionarySource")
+		  },
+		  sample_block{sample_block}, context(context),
+		  table{config.getString(config_prefix + "table")},
+		  load_all_query{composeLoadAllQuery(sample_block, table)}
+	{}
+
+private:
+	BlockInputStreamPtr loadAll() override
+	{
+		if (is_local)
+			return executeQuery(load_all_query, context).in;
+		return new RemoteBlockInputStream{pool.get(), load_all_query, nullptr};
+	}
+
+	BlockInputStreamPtr loadId(const std::uint64_t id) override
+	{
+		throw Exception{
+			"Method unsupported",
+			ErrorCodes::NOT_IMPLEMENTED
+		};
+	}
+
+	BlockInputStreamPtr loadIds(const std::vector<std::uint64_t> ids) override
+	{
+		throw Exception{
+			"Method unsupported",
+			ErrorCodes::NOT_IMPLEMENTED
+		};
+	}
+
+	static std::string composeLoadAllQuery(const Block & block, const std::string & table)
+	{
+		std::string query{"SELECT "};
+
+		auto first = true;
+		for (const auto idx : ext::range(0, block.columns()))
+		{
+			if (!first)
+				query += ", ";
+
+			query += block.getByPosition(idx).name;
+			first = false;
+		}
+
+		query += " FROM " + table + ';';
+
+		return query;
+	}
+
+	static bool isLocal(const std::string & host, const UInt16 port)
+	{
+		const UInt16 clickhouse_port = Poco::Util::Application::instance().config().getInt("tcp_port", 0);
+		static auto interfaces = Poco::Net::NetworkInterface::list();
+
+		if (clickhouse_port == port)
+		{
+			return interfaces.end() != std::find_if(interfaces.begin(), interfaces.end(),
+				[&] (const Poco::Net::NetworkInterface & interface) {
+					return interface.address() == Poco::Net::IPAddress(host);
+				});
+		}
+
+		return false;
+	}
+
+	const std::string host;
+	const UInt16 port;
+	const bool is_local;
+	std::unique_ptr<ConnectionPool> pool;
+	Block sample_block;
+	Context context;
+	const std::string table;
+	const std::string load_all_query;
+};
+
+}

dbms/include/DB/Dictionaries/DictionarySourceFactory.h

@@ -4,6 +4,7 @@
 #include <DB/Dictionaries/DictionaryStructure.h>
 #include <DB/Dictionaries/FileDictionarySource.h>
 #include <DB/Dictionaries/MysqlDictionarySource.h>
+#include <DB/Dictionaries/ClickhouseDictionarySource.h>
 #include <DB/DataTypes/DataTypesNumberFixed.h>
 #include <Yandex/singleton.h>
 #include <statdaemons/ext/memory.hpp>
@@ -57,6 +58,11 @@ public:
 		{
 			return ext::make_unique<MysqlDictionarySource>(config, config_prefix + "mysql.", sample_block, context);
 		}
+		else if (config.has(config_prefix + "clickhouse"))
+		{
+			return ext::make_unique<ClickhouseDictionarySource>(config, config_prefix + "clickhouse.",
+				sample_block, context);
+		}
 
 		throw Exception{"unsupported source type"};
 	}

dbms/include/DB/Dictionaries/MysqlDictionarySource.h

@@ -2,12 +2,10 @@
 
 #include <DB/Interpreters/Context.h>
 #include <DB/Dictionaries/MysqlBlockInputStream.h>
-#include <DB/Dictionaries/DictionaryStructure.h>
 #include <DB/Dictionaries/IDictionarySource.h>
 #include <DB/Dictionaries/config_ptr_t.h>
 #include <statdaemons/ext/range.hpp>
 #include <mysqlxx/Pool.h>
-#include <Poco/Util/AbstractConfiguration.h>
 #include <Poco/Util/LayeredConfiguration.h>
 
 namespace DB