Server packets

value	name	description
0	Hello	Server handshake response
1	Data	Same as client data
2	Exception	Query processing exception
3	Progress	Query progress
4	Pong	Ping response
5	EndOfStream	All packets were transferred
6	ProfileInfo	Profiling data
7	Totals	Total values
8	Extremes	Extreme values (min, max)
9	TablesStatusResponse	Response to TableStatus request
10	Log	Query system log
11	TableColumns	Columns description
12	UUIDs	List of unique parts ids
13	ReadTaskRequest	String (UUID) describes a request for which next task is needed
14	ProfileEvents	Packet with profile events from server

The Data, Totals and Extremes can be compressed.

Hello

Response to client hello.

field	type	value	description
name	String	`Clickhouse`	Server name
version_major	UVarInt	`21`	Server major version
version_minor	UVarInt	`12`	Server minor version
revision	UVarInt	`54452`	Server revision
tz	String	`Europe/Moscow`	Server timezone
display_name	String	`Clickhouse`	Server name for UI
version_patch	UVarInt	`3`	Server patch version

Exception

Server exception during query processing.

field	type	value	description
code	Int32	`60`	See ErrorCodes.cpp.
name	String	`DB::Exception`	Server major version
message	String	`DB::Exception: Table X doesn't exist`	Server minor version
stack_trace	String	~	C++ stack trace
nested	Bool	`true`	More errors

Can be continuous list of exceptions until nested is false.

Progress

Progress of query execution periodically reported by server.

Progress reported in deltas. For totals, accumulate it on client.

field	type	value	description
rows	UVarInt	`65535`	Row count
bytes	UVarInt	`871799`	Byte count
total_rows	UVarInt	`0`	Total rows
wrote_rows	UVarInt	`0`	Rows from client
wrote_bytes	UVarInt	`0`	Bytes from client

Pong

Response for client ping, no packet body.

End of stream

No more Data packets will be sent, query result is fully steamed from server to client. No packet body.

Profile info

field	type
rows	UVarInt
blocks	UVarInt
bytes	UVarInt
applied_limit	Bool
rows_before_limit	UVarInt
calculated_rows_before_limit	Bool

Log

Data block with server log.

Encoded as data block of columns, but is never compressed.

column	type
time	DateTime
time_micro	UInt32
host_name	String
query_id	String
thread_id	UInt64
priority	Int8
source	String
text	String

Profile events

Data block with profile events.

Encoded as data block of columns, but is never compressed.The value type is UInt64 or Int64, depending on server revision.

column	type
host_name	String
current_time	DateTime
thread_id	UInt64
type	Int8
name	String
value	UInt64 or Int64

Introduction

Building

Native protocol

Contributing

Integration development

Roadmap

Hello

Exception

Progress

Pong

End of stream

Profile info

Log

Profile events

​Hello

​Exception

​Progress

​Pong

​End of stream

​Profile info

​Log

​Profile events

Hello

Exception

Progress

Pong

End of stream

Profile info

Log

Profile events