dbms: added format TSKV [#METR-2944].

dbms/include/DB/DataStreams/TSKVRowOutputStream.h

+#pragma once
+
+#include <DB/DataStreams/TabSeparatedRowOutputStream.h>
+
+
+namespace DB
+{
+
+/** Поток для вывода данных в формате TSKV.
+  * TSKV похож на TabSeparated, но перед каждым значением указывается его имя и знак равенства: name=value.
+  * Этот формат весьма неэффективен.
+  */
+class TSKVRowOutputStream : public TabSeparatedRowOutputStream
+{
+public:
+	TSKVRowOutputStream(WriteBuffer & ostr_, const Block & sample_);
+	void writeField(const Field & field) override;
+
+protected:
+	NamesAndTypes fields;
+};
+
+}
+

dbms/src/DataStreams/FormatFactory.cpp

@@ -17,6 +17,7 @@
 #include <DB/DataStreams/BlockOutputStreamFromRowOutputStream.h>
 #include <DB/DataStreams/JSONRowOutputStream.h>
 #include <DB/DataStreams/JSONCompactRowOutputStream.h>
+#include <DB/DataStreams/TSKVRowOutputStream.h>
 #include <DB/DataStreams/PrettyCompactMonoBlockOutputStream.h>
 #include <DB/DataStreams/FormatFactory.h>
 
@@ -83,6 +84,8 @@ BlockOutputStreamPtr FormatFactory::getOutput(const String & name, WriteBuffer &
 		return new BlockOutputStreamFromRowOutputStream(new JSONRowOutputStream(buf, sample));
 	else if (name == "JSONCompact")
 		return new BlockOutputStreamFromRowOutputStream(new JSONCompactRowOutputStream(buf, sample));
+	else if (name == "TSKV")
+		return new BlockOutputStreamFromRowOutputStream(new TSKVRowOutputStream(buf, sample));
 	else if (name == "Null")
 		return new NullBlockOutputStream;
 	else if (name == "PrettyCompactMonoBlock")

dbms/src/DataStreams/TSKVRowOutputStream.cpp

+#include <DB/IO/WriteHelpers.h>
+#include <DB/DataStreams/TSKVRowOutputStream.h>
+
+
+namespace DB
+{
+
+using Poco::SharedPtr;
+
+
+TSKVRowOutputStream::TSKVRowOutputStream(WriteBuffer & ostr_, const Block & sample_)
+	: TabSeparatedRowOutputStream(ostr_, sample_)
+{
+	NamesAndTypesList columns(sample_.getColumnsList());
+	fields.assign(columns.begin(), columns.end());
+
+	for (auto & field : fields)
+	{
+		String escaped_field_name;
+		{
+			WriteBufferFromString wb(escaped_field_name);
+			writeAnyEscapedString<'='>(field.name.data(), field.name.data() + field.name.size(), wb);
+		}
+		field.name = escaped_field_name;
+	}
+}
+
+
+void TSKVRowOutputStream::writeField(const Field & field)
+{
+	writeString(fields[field_number].name, ostr);
+	writeCString("=", ostr);
+	data_types[field_number]->serializeTextEscaped(field, ostr);
+	++field_number;
+}
+
+}