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CQL BINARY PROTOCOL v4
Table of Contents
1. Overview
2. Frame header
2.1. version
2.2. flags
2.3. stream
2.4. opcode
2.5. length
3. Notations
4. Messages
4.1. Requests
4.1.1. STARTUP
4.1.2. AUTH_RESPONSE
4.1.3. OPTIONS
4.1.4. QUERY
4.1.5. PREPARE
4.1.6. EXECUTE
4.1.7. BATCH
4.1.8. REGISTER
4.2. Responses
4.2.1. ERROR
4.2.2. READY
4.2.3. AUTHENTICATE
4.2.4. SUPPORTED
4.2.5. RESULT
4.2.5.1. Void
4.2.5.2. Rows
4.2.5.3. Set_keyspace
4.2.5.4. Prepared
4.2.5.5. Schema_change
4.2.6. EVENT
4.2.7. AUTH_CHALLENGE
4.2.8. AUTH_SUCCESS
5. Compression
6. Data Type Serialization Formats
7. User Defined Type Serialization
8. Result paging
9. Error codes
10. Changes from v3
1. Overview
The CQL binary protocol is a frame based protocol. Frames are defined as:
0 8 16 24 32 40
+---------+---------+---------+---------+---------+
| version | flags | stream | opcode |
+---------+---------+---------+---------+---------+
| length |
+---------+---------+---------+---------+
| |
. ... body ... .
. .
. .
+----------------------------------------
The protocol is big-endian (network byte order).
Each frame contains a fixed size header (9 bytes) followed by a variable size
body. The header is described in Section 2. The content of the body depends
on the header opcode value (the body can in particular be empty for some
opcode values). The list of allowed opcodes is defined in Section 2.4 and the
details of each corresponding message are described Section 4.
The protocol distinguishes two types of frames: requests and responses. Requests
are those frames sent by the client to the server. Responses are those frames sent
by the server to the client. Note, however, that the protocol supports server pushes
(events) so a response does not necessarily come right after a client request.
Note to client implementors: client libraries should always assume that the
body of a given frame may contain more data than what is described in this
document. It will however always be safe to ignore the remainder of the frame
body in such cases. The reason is that this may enable extending the protocol
with optional features without needing to change the protocol version.
2. Frame header
2.1. version
The version is a single byte that indicates both the direction of the message
(request or response) and the version of the protocol in use. The most
significant bit of version is used to define the direction of the message:
0 indicates a request, 1 indicates a response. This can be useful for protocol
analyzers to distinguish the nature of the packet from the direction in which
it is moving. The rest of that byte is the protocol version (4 for the protocol
defined in this document). In other words, for this version of the protocol,
version will be one of:
0x04 Request frame for this protocol version
0x84 Response frame for this protocol version
Please note that while every message ships with the version, only one version
of messages is accepted on a given connection. In other words, the first message
exchanged (STARTUP) sets the version for the connection for the lifetime of this
connection.
This document describes version 4 of the protocol. For the changes made since
version 3, see Section 10.
2.2. flags
Flags applying to this frame. The flags have the following meaning (described
by the mask that allows selecting them):
0x01: Compression flag. If set, the frame body is compressed. The actual
compression to use should have been set up beforehand through the
Startup message (which thus cannot be compressed; Section 4.1.1).
0x02: Tracing flag. For a request frame, this indicates the client requires
tracing of the request. Note that only QUERY, PREPARE and EXECUTE queries
support tracing. Other requests will simply ignore the tracing flag if
set. If a request supports tracing and the tracing flag is set, the response
to this request will have the tracing flag set and contain tracing
information.
If a response frame has the tracing flag set, its body contains
a tracing ID. The tracing ID is a [uuid] and is the first thing in
the frame body.
0x04: Custom payload flag. For a request or response frame, this indicates
that a generic key-value custom payload for a custom QueryHandler
implementation is present in the frame. Such a custom payload is simply
ignored by the default QueryHandler implementation.
Currently, only QUERY, PREPARE, EXECUTE and BATCH requests support
payload.
Type of custom payload is [bytes map] (see below). If either or both
of the tracing and warning flags are set, the custom payload will follow
those indicated elements in the frame body. If neither are set, the custom
payload will be the first value in the frame body.
0x08: Warning flag. The response contains warnings which were generated by the
server to go along with this response.
If a response frame has the warning flag set, its body will contain the
text of the warnings. The warnings are a [string list] and will be the
first value in the frame body if the tracing flag is not set, or directly
after the tracing ID if it is.
The rest of flags is currently unused and ignored.
2.3. stream
A frame has a stream id (a [short] value). When sending request messages, this
stream id must be set by the client to a non-negative value (negative stream id
are reserved for streams initiated by the server; currently all EVENT messages
(section 4.2.6) have a streamId of -1). If a client sends a request message
with the stream id X, it is guaranteed that the stream id of the response to
that message will be X.
This helps to enable the asynchronous nature of the protocol. If a client
sends multiple messages simultaneously (without waiting for responses), there
is no guarantee on the order of the responses. For instance, if the client
writes REQ_1, REQ_2, REQ_3 on the wire (in that order), the server might
respond to REQ_3 (or REQ_2) first. Assigning different stream ids to these 3
requests allows the client to distinguish to which request a received answer
responds to. As there can only be 32768 different simultaneous streams, it is up
to the client to reuse stream id.
Note that clients are free to use the protocol synchronously (i.e. wait for
the response to REQ_N before sending REQ_N+1). In that case, the stream id
can be safely set to 0. Clients should also feel free to use only a subset of
the 32768 maximum possible stream ids if it is simpler for its implementation.
2.4. opcode
An integer byte that distinguishes the actual message:
0x00 ERROR
0x01 STARTUP
0x02 READY
0x03 AUTHENTICATE
0x05 OPTIONS
0x06 SUPPORTED
0x07 QUERY
0x08 RESULT
0x09 PREPARE
0x0A EXECUTE
0x0B REGISTER
0x0C EVENT
0x0D BATCH
0x0E AUTH_CHALLENGE
0x0F AUTH_RESPONSE
0x10 AUTH_SUCCESS
Messages are described in Section 4.
(Note that there is no 0x04 message in this version of the protocol)
2.5. length
A 4 byte integer representing the length of the body of the frame (note:
currently a frame is limited to 256MB in length).
3. Notations
To describe the layout of the frame body for the messages in Section 4, we
define the following:
[int] A 4 bytes integer
[long] A 8 bytes integer
[short] A 2 bytes unsigned integer
[string] A [short] n, followed by n bytes representing an UTF-8
string.
[long string] An [int] n, followed by n bytes representing an UTF-8 string.
[uuid] A 16 bytes long uuid.
[string list] A [short] n, followed by n [string].
[bytes] A [int] n, followed by n bytes if n >= 0. If n < 0,
no byte should follow and the value represented is `null`.
[value] A [int] n, followed by n bytes if n >= 0.
If n == -1 no byte should follow and the value represented is `null`.
If n == -2 no byte should follow and the value represented is
`not set` not resulting in any change to the existing value.
n < -2 is an invalid value and results in an error.
[short bytes] A [short] n, followed by n bytes if n >= 0.
[option] A pair of <id><value> where <id> is a [short] representing
the option id and <value> depends on that option (and can be
of size 0). The supported id (and the corresponding <value>)
will be described when this is used.
[option list] A [short] n, followed by n [option].
[inet] An address (ip and port) to a node. It consists of one
[byte] n, that represents the address size, followed by n
[byte] representing the IP address (in practice n can only be
either 4 (IPv4) or 16 (IPv6)), following by one [int]
representing the port.
[consistency] A consistency level specification. This is a [short]
representing a consistency level with the following
correspondence:
0x0000 ANY
0x0001 ONE
0x0002 TWO
0x0003 THREE
0x0004 QUORUM
0x0005 ALL
0x0006 LOCAL_QUORUM
0x0007 EACH_QUORUM
0x0008 SERIAL
0x0009 LOCAL_SERIAL
0x000A LOCAL_ONE
[string map] A [short] n, followed by n pair <k><v> where <k> and <v>
are [string].
[string multimap] A [short] n, followed by n pair <k><v> where <k> is a
[string] and <v> is a [string list].
[bytes map] A [short] n, followed by n pair <k><v> where <k> is a
[string] and <v> is a [bytes].
4. Messages
Dependant on the flags specified in the header, the layout of the message body must be:
[<tracing_id>][<warnings>][<custom_payload>]<message>
where:
- <tracing_id> is a UUID tracing ID, present if this is a request message and the Tracing flag is set.
- <warnings> is a string list of warnings (if this is a request message and the Warning flag is set.
- <custom_payload> is bytes map for the serialised custom payload present if this is one of the message types
which support custom payloads (QUERY, PREPARE, EXECUTE and BATCH) and the Custom payload flag is set.
- <message> as defined below through sections 4 and 5.
4.1. Requests
Note that outside of their normal responses (described below), all requests
can get an ERROR message (Section 4.2.1) as response.
4.1.1. STARTUP
Initialize the connection. The server will respond by either a READY message
(in which case the connection is ready for queries) or an AUTHENTICATE message
(in which case credentials will need to be provided using AUTH_RESPONSE).
This must be the first message of the connection, except for OPTIONS that can
be sent before to find out the options supported by the server. Once the
connection has been initialized, a client should not send any more STARTUP
messages.
The body is a [string map] of options. Possible options are:
- "CQL_VERSION": the version of CQL to use. This option is mandatory and
currently the only version supported is "3.0.0". Note that this is
different from the protocol version.
- "COMPRESSION": the compression algorithm to use for frames (See section 5).
This is optional; if not specified no compression will be used.
- "NO_COMPACT": whether or not connection has to be established in compatibility
mode. This mode will make all Thrift and Compact Tables to be exposed as if
they were CQL Tables. This is optional; if not specified, the option will
not be used.
- "THROW_ON_OVERLOAD": In case of server overloaded with too many requests, by default the server puts
back pressure on the client connection. Instead, the server can send an OverloadedException error message back to
the client if this option is set to true.
4.1.2. AUTH_RESPONSE
Answers a server authentication challenge.
Authentication in the protocol is SASL based. The server sends authentication
challenges (a bytes token) to which the client answers with this message. Those
exchanges continue until the server accepts the authentication by sending a
AUTH_SUCCESS message after a client AUTH_RESPONSE. Note that the exchange
begins with the client sending an initial AUTH_RESPONSE in response to a
server AUTHENTICATE request.
The body of this message is a single [bytes] token. The details of what this
token contains (and when it can be null/empty, if ever) depends on the actual
authenticator used.
The response to a AUTH_RESPONSE is either a follow-up AUTH_CHALLENGE message,
an AUTH_SUCCESS message or an ERROR message.
4.1.3. OPTIONS
Asks the server to return which STARTUP options are supported. The body of an
OPTIONS message should be empty and the server will respond with a SUPPORTED
message.
4.1.4. QUERY
Performs a CQL query. The body of the message must be:
<query><query_parameters>
where <query> is a [long string] representing the query and
<query_parameters> must be
<consistency><flags>[<n>[name_1]<value_1>...[name_n]<value_n>][<result_page_size>][<paging_state>][<serial_consistency>][<timestamp>]
where:
- <consistency> is the [consistency] level for the operation.
- <flags> is a [byte] whose bits define the options for this query and
in particular influence what the remainder of the message contains.
A flag is set if the bit corresponding to its `mask` is set. Supported
flags are, given their mask:
0x01: Values. If set, a [short] <n> followed by <n> [value]
values are provided. Those values are used for bound variables in
the query. Optionally, if the 0x40 flag is present, each value
will be preceded by a [string] name, representing the name of
the marker the value must be bound to.
0x02: Skip_metadata. If set, the Result Set returned as a response
to the query (if any) will have the NO_METADATA flag (see
Section 4.2.5.2).
0x04: Page_size. If set, <result_page_size> is an [int]
controlling the desired page size of the result (in CQL3 rows).
See the section on paging (Section 8) for more details.
0x08: With_paging_state. If set, <paging_state> should be present.
<paging_state> is a [bytes] value that should have been returned
in a result set (Section 4.2.5.2). The query will be
executed but starting from a given paging state. This is also to
continue paging on a different node than the one where it
started (See Section 8 for more details).
0x10: With serial consistency. If set, <serial_consistency> should be
present. <serial_consistency> is the [consistency] level for the
serial phase of conditional updates. Consistency can be
SERIAL or LOCAL_SERIAL, if not present, it defaults to
SERIAL. This option will be ignored for anything else other than a
conditional update/insert.
0x20: With default timestamp. If set, <timestamp> should be present.
<timestamp> is a [long] representing the default timestamp for the query
in microseconds (negative values are forbidden). This will
replace the server side assigned timestamp as default timestamp.
Note that a timestamp in the query itself will still override
this timestamp. This is entirely optional.
0x40: With names for values. This only makes sense if the 0x01 flag is set and
is ignored otherwise. If present, the values from the 0x01 flag will
be preceded by a name (see above). Note that this is only useful for
QUERY requests where named bind markers are used; for EXECUTE statements,
since the names for the expected values was returned during preparation,
a client can always provide values in the right order without any names
and using this flag, while supported, is almost surely inefficient.
Note that the consistency is ignored by some queries (USE, CREATE, ALTER,
TRUNCATE, ...).
The server will respond to a QUERY message with a RESULT message, the content
of which depends on the query.
4.1.5. PREPARE
Prepare a query for later execution (through EXECUTE). The body consists of
the CQL query to prepare as a [long string].
The server will respond with a RESULT message with a `prepared` kind (0x0004,
see Section 4.2.5).
4.1.6. EXECUTE
Executes a prepared query. The body of the message must be:
<id><query_parameters>
where <id> is the prepared query ID. It's the [short bytes] returned as a
response to a PREPARE message. As for <query_parameters>, it has the exact
same definition as in QUERY (see Section 4.1.4).
The response from the server will be a RESULT message.
4.1.7. BATCH
Allows executing a list of queries (prepared or not) as a batch (note that
only DML statements are accepted in a batch). The body of the message must
be:
<type><n><query_1>...<query_n><consistency><flags>[<serial_consistency>][<timestamp>]
where:
- <type> is a [byte] indicating the type of batch to use:
- If <type> == 0, the batch will be "logged". This is equivalent to a
normal CQL3 batch statement.
- If <type> == 1, the batch will be "unlogged".
- If <type> == 2, the batch will be a "counter" batch (and non-counter
statements will be rejected).
- <flags> is a [byte] whose bits define the options for this query and
in particular influence what the remainder of the message contains. It is similar
to the <flags> from QUERY and EXECUTE methods, except that the 4 rightmost
bits must always be 0 as their corresponding options do not make sense for
Batch. A flag is set if the bit corresponding to its `mask` is set. Supported
flags are, given their mask:
0x10: With serial consistency. If set, <serial_consistency> should be
present. <serial_consistency> is the [consistency] level for the
serial phase of conditional updates. Consistency can be
either SERIAL or LOCAL_SERIAL, and if not present, it defaults to
SERIAL. This option will be ignored for anything else other than a
conditional update/insert.
0x20: With default timestamp. If set, <timestamp> should be present.
<timestamp> is a [long] representing the default timestamp for the query
in microseconds. This will replace the server side assigned
timestamp as default timestamp. Note that a timestamp in the query itself
will still override this timestamp. This is entirely optional.
0x40: With names for values. If set, then all values for all <query_i> must be
preceded by a [string] <name_i> that have the same meaning as in QUERY
requests [IMPORTANT NOTE: this feature does not work and should not be
used. It is specified in a way that makes it impossible for the server
to implement. This will be fixed in a future version of the native
protocol. See https://issues.apache.org/jira/browse/CASSANDRA-10246 for
more details].
- <n> is a [short] indicating the number of following queries.
- <query_1>...<query_n> are the queries to execute. A <query_i> must be of the
form:
<kind><string_or_id><n>[<name_1>]<value_1>...[<name_n>]<value_n>
where:
- <kind> is a [byte] indicating whether the following query is a prepared
one or not. <kind> value must be either 0 or 1.
- <string_or_id> depends on the value of <kind>. If <kind> == 0, it should be
a [long string] query string (as in QUERY, the query string might contain
bind markers). Otherwise (that is, if <kind> == 1), it should be a
[short bytes] representing a prepared query ID.
- <n> is a [short] indicating the number (possibly 0) of following values.
- <name_i> is the optional name of the following <value_i>. It must be present
if and only if the 0x40 flag is provided for the batch.
- <value_i> is the [value] to use for bound variable i (of bound variable <name_i>
if the 0x40 flag is used).
- <consistency> is the [consistency] level for the operation.
- <serial_consistency> is only present if the 0x10 flag is set. In that case,
<serial_consistency> is the [consistency] level for the serial phase of
conditional updates. Consistency can be SERIAL or
LOCAL_SERIAL, if not present, it defaults to SERIAL. This option will
be ignored for anything else other than a conditional update/insert.
The server will respond with a RESULT message.
4.1.8. REGISTER
Register this connection to receive some types of events. The body of the
message is a [string list] representing the event types to register for. See
section 4.2.6 for the list of valid event types.
The response to a REGISTER message will be a READY message.
Please note that if a client driver maintains multiple connections to a
Cassandra node and/or connections to multiple nodes, it is advised to
dedicate a handful of connections to receive events, but to *not* register
for events on all connections, as this would only result in receiving
multiple times the same event messages, wasting bandwidth.
4.2. Responses
This section describes the content of the frame body for the different
responses. Please note that to make room for future evolution, clients should
support extra information (that they should simply discard) to the one
described in this document at the end of the frame body.
4.2.1. ERROR
Indicates an error processing a request. The body of the message will be an
error code ([int]) followed by a [string] error message. Then, depending on
the exception, more content may follow. The error codes are defined in
Section 9, along with their additional content if any.
4.2.2. READY
Indicates that the server is ready to process queries. This message will be
sent by the server either after a STARTUP message if no authentication is
required (if authentication is required, the server indicates readiness by
sending a AUTH_RESPONSE message).
The body of a READY message is empty.
4.2.3. AUTHENTICATE
Indicates that the server requires authentication, and which authentication
mechanism to use.
The authentication is SASL based and thus consists of a number of server
challenges (AUTH_CHALLENGE, Section 4.2.7) followed by client responses
(AUTH_RESPONSE, Section 4.1.2). The initial exchange is however bootstrapped
by an initial client response. The details of that exchange (including how
many challenge-response pairs are required) are specific to the authenticator
in use. The exchange ends when the server sends an AUTH_SUCCESS message or
an ERROR message.
This message will be sent following a STARTUP message if authentication is
required and must be answered by a AUTH_RESPONSE message from the client.
The body consists of a single [string] indicating the full class name of the
IAuthenticator in use.
4.2.4. SUPPORTED
Indicates which startup options are supported by the server. This message
comes as a response to an OPTIONS message.
The body of a SUPPORTED message is a [string multimap]. This multimap gives
for each of the supported STARTUP options, the list of supported values.
4.2.5. RESULT
The result to a query (QUERY, PREPARE, EXECUTE or BATCH messages).
The first element of the body of a RESULT message is an [int] representing the
`kind` of result. The rest of the body depends on the kind. The kind can be
one of:
0x0001 Void: for results carrying no information.
0x0002 Rows: for results to select queries, returning a set of rows.
0x0003 Set_keyspace: the result to a `use` query.
0x0004 Prepared: result to a PREPARE message.
0x0005 Schema_change: the result to a schema altering query.
The body for each kind (after the [int] kind) is defined below.
4.2.5.1. Void
The rest of the body for a Void result is empty. It indicates that a query was
successful without providing more information.
4.2.5.2. Rows
Indicates a set of rows. The rest of the body of a Rows result is:
<metadata><rows_count><rows_content>
where:
- <metadata> is composed of:
<flags><columns_count>[<paging_state>][<global_table_spec>?<col_spec_1>...<col_spec_n>]
where:
- <flags> is an [int]. The bits of <flags> provides information on the
formatting of the remaining information. A flag is set if the bit
corresponding to its `mask` is set. Supported flags are, given their
mask:
0x0001 Global_tables_spec: if set, only one table spec (keyspace
and table name) is provided as <global_table_spec>. If not
set, <global_table_spec> is not present.
0x0002 Has_more_pages: indicates whether this is not the last
page of results and more should be retrieved. If set, the
<paging_state> will be present. The <paging_state> is a
[bytes] value that should be used in QUERY/EXECUTE to
continue paging and retrieve the remainder of the result for
this query (See Section 8 for more details).
0x0004 No_metadata: if set, the <metadata> is only composed of
these <flags>, the <column_count> and optionally the
<paging_state> (depending on the Has_more_pages flag) but
no other information (so no <global_table_spec> nor <col_spec_i>).
This will only ever be the case if this was requested
during the query (see QUERY and RESULT messages).
- <columns_count> is an [int] representing the number of columns selected
by the query that produced this result. It defines the number of <col_spec_i>
elements in and the number of elements for each row in <rows_content>.
- <global_table_spec> is present if the Global_tables_spec is set in
<flags>. It is composed of two [string] representing the
(unique) keyspace name and table name the columns belong to.
- <col_spec_i> specifies the columns returned in the query. There are
<column_count> such column specifications that are composed of:
(<ks_name><table_name>)?<name><type>
The initial <ks_name> and <table_name> are two [string] and are only present
if the Global_tables_spec flag is not set. The <column_name> is a
[string] and <type> is an [option] that corresponds to the description
(what this description is depends a bit on the context: in results to
selects, this will be either the user chosen alias or the selection used
(often a colum name, but it can be a function call too). In results to
a PREPARE, this will be either the name of the corresponding bind variable
or the column name for the variable if it is "anonymous") and type of
the corresponding result. The option for <type> is either a native
type (see below), in which case the option has no value, or a
'custom' type, in which case the value is a [string] representing
the fully qualified class name of the type represented. Valid option
ids are:
0x0000 Custom: the value is a [string], see above.
0x0001 Ascii
0x0002 Bigint
0x0003 Blob
0x0004 Boolean
0x0005 Counter
0x0006 Decimal
0x0007 Double
0x0008 Float
0x0009 Int
0x000B Timestamp
0x000C Uuid
0x000D Varchar
0x000E Varint
0x000F Timeuuid
0x0010 Inet
0x0011 Date
0x0012 Time
0x0013 Smallint
0x0014 Tinyint
0x0020 List: the value is an [option], representing the type
of the elements of the list.
0x0021 Map: the value is two [option], representing the types of the
keys and values of the map
0x0022 Set: the value is an [option], representing the type
of the elements of the set
0x0030 UDT: the value is <ks><udt_name><n><name_1><type_1>...<name_n><type_n>
where:
- <ks> is a [string] representing the keyspace name this
UDT is part of.
- <udt_name> is a [string] representing the UDT name.
- <n> is a [short] representing the number of fields of
the UDT, and thus the number of <name_i><type_i> pairs
following
- <name_i> is a [string] representing the name of the
i_th field of the UDT.
- <type_i> is an [option] representing the type of the
i_th field of the UDT.
0x0031 Tuple: the value is <n><type_1>...<type_n> where <n> is a [short]
representing the number of values in the type, and <type_i>
are [option] representing the type of the i_th component
of the tuple
- <rows_count> is an [int] representing the number of rows present in this
result. Those rows are serialized in the <rows_content> part.
- <rows_content> is composed of <row_1>...<row_m> where m is <rows_count>.
Each <row_i> is composed of <value_1>...<value_n> where n is
<columns_count> and where <value_j> is a [bytes] representing the value
returned for the jth column of the ith row. In other words, <rows_content>
is composed of (<rows_count> * <columns_count>) [bytes].
4.2.5.3. Set_keyspace
The result to a `use` query. The body (after the kind [int]) is a single
[string] indicating the name of the keyspace that has been set.
4.2.5.4. Prepared
The result to a PREPARE message. The body of a Prepared result is:
<id><metadata><result_metadata>
where:
- <id> is [short bytes] representing the prepared query ID.
- <metadata> is composed of:
<flags><columns_count><pk_count>[<pk_index_1>...<pk_index_n>][<global_table_spec>?<col_spec_1>...<col_spec_n>]
where:
- <flags> is an [int]. The bits of <flags> provides information on the
formatting of the remaining information. A flag is set if the bit
corresponding to its `mask` is set. Supported masks and their flags
are:
0x0001 Global_tables_spec: if set, only one table spec (keyspace
and table name) is provided as <global_table_spec>. If not
set, <global_table_spec> is not present.
- <columns_count> is an [int] representing the number of bind markers
in the prepared statement. It defines the number of <col_spec_i>
elements.
- <pk_count> is an [int] representing the number of <pk_index_i>
elements to follow. If this value is zero, at least one of the
partition key columns in the table that the statement acts on
did not have a corresponding bind marker (or the bind marker
was wrapped in a function call).
- <pk_index_i> is a short that represents the index of the bind marker
that corresponds to the partition key column in position i.
For example, a <pk_index> sequence of [2, 0, 1] indicates that the
table has three partition key columns; the full partition key
can be constructed by creating a composite of the values for
the bind markers at index 2, at index 0, and at index 1.
This allows implementations with token-aware routing to correctly
construct the partition key without needing to inspect table
metadata.
- <global_table_spec> is present if the Global_tables_spec is set in
<flags>. If present, it is composed of two [string]s. The first
[string] is the name of the keyspace that the statement acts on.
The second [string] is the name of the table that the columns
represented by the bind markers belong to.
- <col_spec_i> specifies the bind markers in the prepared statement.
There are <column_count> such column specifications, each with the
following format:
(<ks_name><table_name>)?<name><type>
The initial <ks_name> and <table_name> are two [string] that are only
present if the Global_tables_spec flag is not set. The <name> field
is a [string] that holds the name of the bind marker (if named),
or the name of the column, field, or expression that the bind marker
corresponds to (if the bind marker is "anonymous"). The <type>
field is an [option] that represents the expected type of values for
the bind marker. See the Rows documentation (section 4.2.5.2) for
full details on the <type> field.
- <result_metadata> is defined exactly the same as <metadata> in the Rows
documentation (section 4.2.5.2). This describes the metadata for the
result set that will be returned when this prepared statement is executed.
Note that <result_metadata> may be empty (have the No_metadata flag and
0 columns, See section 4.2.5.2) and will be for any query that is not a
Select. In fact, there is never a guarantee that this will be non-empty, so
implementations should protect themselves accordingly. This result metadata
is an optimization that allows implementations to later execute the
prepared statement without requesting the metadata (see the Skip_metadata
flag in EXECUTE). Clients can safely discard this metadata if they do not
want to take advantage of that optimization.
Note that the prepared query ID returned is global to the node on which the query
has been prepared. It can be used on any connection to that node
until the node is restarted (after which the query must be re-prepared).
4.2.5.5. Schema_change
The result to a schema altering query (creation/update/drop of a
keyspace/table/index). The body (after the kind [int]) is the same
as the body for a "SCHEMA_CHANGE" event, so 3 strings:
<change_type><target><options>
Please refer to section 4.2.6 below for the meaning of those fields.
Note that a query to create or drop an index is considered to be a change
to the table the index is on.
4.2.6. EVENT
An event pushed by the server. A client will only receive events for the
types it has REGISTER-ed to. The body of an EVENT message will start with a
[string] representing the event type. The rest of the message depends on the
event type. The valid event types are:
- "TOPOLOGY_CHANGE": events related to change in the cluster topology.
Currently, events are sent when new nodes are added to the cluster, and
when nodes are removed. The body of the message (after the event type)
consists of a [string] and an [inet], corresponding respectively to the
type of change ("NEW_NODE" or "REMOVED_NODE") followed by the address of
the new/removed node.
- "STATUS_CHANGE": events related to change of node status. Currently,
up/down events are sent. The body of the message (after the event type)
consists of a [string] and an [inet], corresponding respectively to the
type of status change ("UP" or "DOWN") followed by the address of the
concerned node.
- "SCHEMA_CHANGE": events related to schema change. After the event type,
the rest of the message will be <change_type><target><options> where:
- <change_type> is a [string] representing the type of changed involved.
It will be one of "CREATED", "UPDATED" or "DROPPED".
- <target> is a [string] that can be one of "KEYSPACE", "TABLE", "TYPE",
"FUNCTION" or "AGGREGATE" and describes what has been modified
("TYPE" stands for modifications related to user types, "FUNCTION"
for modifications related to user defined functions, "AGGREGATE"
for modifications related to user defined aggregates).
- <options> depends on the preceding <target>:
- If <target> is "KEYSPACE", then <options> will be a single [string]
representing the keyspace changed.
- If <target> is "TABLE" or "TYPE", then
<options> will be 2 [string]: the first one will be the keyspace
containing the affected object, and the second one will be the name
of said affected object (either the table, user type, function, or
aggregate name).
- If <target> is "FUNCTION" or "AGGREGATE", multiple arguments follow:
- [string] keyspace containing the user defined function / aggregate
- [string] the function/aggregate name
- [string list] one string for each argument type (as CQL type)
All EVENT messages have a streamId of -1 (Section 2.3).
Please note that "NEW_NODE" and "UP" events are sent based on internal Gossip
communication and as such may be sent a short delay before the binary
protocol server on the newly up node is fully started. Clients are thus
advised to wait a short time before trying to connect to the node (1 second
should be enough), otherwise they may experience a connection refusal at
first.
4.2.7. AUTH_CHALLENGE
A server authentication challenge (see AUTH_RESPONSE (Section 4.1.2) for more
details).
The body of this message is a single [bytes] token. The details of what this
token contains (and when it can be null/empty, if ever) depends on the actual
authenticator used.
Clients are expected to answer the server challenge with an AUTH_RESPONSE
message.
4.2.8. AUTH_SUCCESS
Indicates the success of the authentication phase. See Section 4.2.3 for more
details.
The body of this message is a single [bytes] token holding final information
from the server that the client may require to finish the authentication
process. What that token contains and whether it can be null depends on the
actual authenticator used.
5. Compression
Frame compression is supported by the protocol, but then only the frame body
is compressed (the frame header should never be compressed).
Before being used, client and server must agree on a compression algorithm to
use, which is done in the STARTUP message. As a consequence, a STARTUP message
must never be compressed. However, once the STARTUP frame has been received
by the server, messages can be compressed (including the response to the STARTUP
request). Frames do not have to be compressed, however, even if compression has
been agreed upon (a server may only compress frames above a certain size at its
discretion). A frame body should be compressed if and only if the compressed
flag (see Section 2.2) is set.
As of version 2 of the protocol, the following compressions are available:
- lz4 (https://code.google.com/p/lz4/). In that, note that the first four bytes
of the body will be the uncompressed length (followed by the compressed
bytes).
- snappy (https://code.google.com/p/snappy/). This compression might not be
available as it depends on a native lib (server-side) that might not be
available on some installations.
6. Data Type Serialization Formats
This sections describes the serialization formats for all CQL data types
supported by Cassandra through the native protocol. These serialization
formats should be used by client drivers to encode values for EXECUTE
messages. Cassandra will use these formats when returning values in
RESULT messages.
All values are represented as [bytes] in EXECUTE and RESULT messages.
The [bytes] format includes an int prefix denoting the length of the value.
For that reason, the serialization formats described here will not include
a length component.
For legacy compatibility reasons, note that most non-string types support
"empty" values (i.e. a value with zero length). An empty value is distinct
from NULL, which is encoded with a negative length.
As with the rest of the native protocol, all encodings are big-endian.
6.1. ascii
A sequence of bytes in the ASCII range [0, 127]. Bytes with values outside of
this range will result in a validation error.
6.2 bigint
An eight-byte two's complement integer.
6.3 blob
Any sequence of bytes.
6.4 boolean
A single byte. A value of 0 denotes "false"; any other value denotes "true".
(However, it is recommended that a value of 1 be used to represent "true".)
6.5 date
An unsigned integer representing days with epoch centered at 2^31.
(unix epoch January 1st, 1970).
A few examples:
0: -5877641-06-23
2^31: 1970-1-1
2^32: 5881580-07-11
6.6 decimal
The decimal format represents an arbitrary-precision number. It contains an
[int] "scale" component followed by a varint encoding (see section 6.17)
of the unscaled value. The encoded value represents "<unscaled>E<-scale>".
In other words, "<unscaled> * 10 ^ (-1 * <scale>)".
6.7 double
An 8 byte floating point number in the IEEE 754 binary64 format.
6.8 float
A 4 byte floating point number in the IEEE 754 binary32 format.
6.9 inet
A 4 byte or 16 byte sequence denoting an IPv4 or IPv6 address, respectively.
6.10 int
A 4 byte two's complement integer.
6.11 list
A [int] n indicating the number of elements in the list, followed by n
elements. Each element is [bytes] representing the serialized value.
6.12 map
A [int] n indicating the number of key/value pairs in the map, followed by
n entries. Each entry is composed of two [bytes] representing the key
and value.
6.13 set
A [int] n indicating the number of elements in the set, followed by n
elements. Each element is [bytes] representing the serialized value.
6.14 smallint
A 2 byte two's complement integer.
6.15 text
A sequence of bytes conforming to the UTF-8 specifications.
6.16 time
An 8 byte two's complement long representing nanoseconds since midnight.
Valid values are in the range 0 to 86399999999999
6.17 timestamp
An 8 byte two's complement integer representing a millisecond-precision
offset from the unix epoch (00:00:00, January 1st, 1970). Negative values
represent a negative offset from the epoch.
6.18 timeuuid
A 16 byte sequence representing a version 1 UUID as defined by RFC 4122.
6.19 tinyint
A 1 byte two's complement integer.
6.20 tuple
A sequence of [bytes] values representing the items in a tuple. The encoding
of each element depends on the data type for that position in the tuple.
Null values may be represented by using length -1 for the [bytes]
representation of an element.
6.21 uuid
A 16 byte sequence representing any valid UUID as defined by RFC 4122.
6.22 varchar
An alias of the "text" type.
6.23 varint
A variable-length two's complement encoding of a signed integer.
The following examples may help implementors of this spec:
Value | Encoding
------|---------
0 | 0x00
1 | 0x01
127 | 0x7F
128 | 0x0080
129 | 0x0081
-1 | 0xFF
-128 | 0x80
-129 | 0xFF7F
Note that positive numbers must use a most-significant byte with a value
less than 0x80, because a most-significant bit of 1 indicates a negative
value. Implementors should pad positive values that have a MSB >= 0x80
with a leading 0x00 byte.
7. User Defined Types
This section describes the serialization format for User defined types (UDT),
as described in section 4.2.5.2.
A UDT value is composed of successive [bytes] values, one for each field of the UDT
value (in the order defined by the type). A UDT value will generally have one value
for each field of the type it represents, but it is allowed to have less values than
the type has fields.
8. Result paging
The protocol allows for paging the result of queries. For that, the QUERY and
EXECUTE messages have a <result_page_size> value that indicate the desired
page size in CQL3 rows.
If a positive value is provided for <result_page_size>, the result set of the
RESULT message returned for the query will contain at most the
<result_page_size> first rows of the query result. If that first page of results
contains the full result set for the query, the RESULT message (of kind `Rows`)
will have the Has_more_pages flag *not* set. However, if some results are not
part of the first response, the Has_more_pages flag will be set and the result
will contain a <paging_state> value. In that case, the <paging_state> value
should be used in a QUERY or EXECUTE message (that has the *same* query as
the original one or the behavior is undefined) to retrieve the next page of
results.
Only CQL3 queries that return a result set (RESULT message with a Rows `kind`)
support paging. For other type of queries, the <result_page_size> value is
ignored.
Note to client implementors:
- While <result_page_size> can be as low as 1, it will likely be detrimental
to performance to pick a value too low. A value below 100 is probably too
low for most use cases.
- Clients should not rely on the actual size of the result set returned to
decide if there are more results to fetch or not. Instead, they should always
check the Has_more_pages flag (unless they did not enable paging for the query
obviously). Clients should also not assert that no result will have more than
<result_page_size> results. While the current implementation always respects
the exact value of <result_page_size>, we reserve the right to return
slightly smaller or bigger pages in the future for performance reasons.
- The <paging_state> is specific to a protocol version and drivers should not
send a <paging_state> returned by a node using the protocol v3 to query a node
using the protocol v4 for instance.
9. Error codes
Let us recall that an ERROR message is composed of <code><message>[...]
(see 4.2.1 for details). The supported error codes, as well as any additional
information the message may contain after the <message> are described below:
0x0000 Server error: something unexpected happened. This indicates a
server-side bug.
0x000A Protocol error: some client message triggered a protocol
violation (for instance a QUERY message is sent before a STARTUP
one has been sent)
0x0100 Authentication error: authentication was required and failed. The
possible reason for failing depends on the authenticator in use,
which may or may not include more detail in the accompanying
error message.
0x1000 Unavailable exception. The rest of the ERROR message body will be
<cl><required><alive>
where:
<cl> is the [consistency] level of the query that triggered
the exception.
<required> is an [int] representing the number of nodes that
should be alive to respect <cl>
<alive> is an [int] representing the number of replicas that
were known to be alive when the request had been
processed (since an unavailable exception has been
triggered, there will be <alive> < <required>)
0x1001 Overloaded: the request cannot be processed because the
coordinator node is overloaded
0x1002 Is_bootstrapping: the request was a read request but the
coordinator node is bootstrapping
0x1003 Truncate_error: error during a truncation error.
0x1100 Write_timeout: Timeout exception during a write request. The rest
of the ERROR message body will be
<cl><received><blockfor><writeType>
where:
<cl> is the [consistency] level of the query having triggered
the exception.
<received> is an [int] representing the number of nodes having
acknowledged the request.
<blockfor> is an [int] representing the number of replicas whose
acknowledgement is required to achieve <cl>.
<writeType> is a [string] that describe the type of the write
that timed out. The value of that string can be one
of:
- "SIMPLE": the write was a non-batched
non-counter write.
- "BATCH": the write was a (logged) batch write.
If this type is received, it means the batch log
has been successfully written (otherwise a
"BATCH_LOG" type would have been sent instead).
- "UNLOGGED_BATCH": the write was an unlogged
batch. No batch log write has been attempted.
- "COUNTER": the write was a counter write
(batched or not).
- "BATCH_LOG": the timeout occurred during the
write to the batch log when a (logged) batch
write was requested.
- "CAS": the timeout occurred during the Compare And Set write/update.
- "VIEW": the timeout occurred when a write involves
VIEW update and failure to acquire local view(MV)
lock for key within timeout
- "CDC": the timeout occurred when cdc_total_space is
exceeded when doing a write to data tracked by cdc.
0x1200 Read_timeout: Timeout exception during a read request. The rest
of the ERROR message body will be
<cl><received><blockfor><data_present>
where:
<cl> is the [consistency] level of the query having triggered
the exception.
<received> is an [int] representing the number of nodes having
answered the request.
<blockfor> is an [int] representing the number of replicas whose
response is required to achieve <cl>. Please note that
it is possible to have <received> >= <blockfor> if
<data_present> is false. Also in the (unlikely)
case where <cl> is achieved but the coordinator node
times out while waiting for read-repair acknowledgement.
<data_present> is a single byte. If its value is 0, it means
the replica that was asked for data has not
responded. Otherwise, the value is != 0.
0x1300 Read_failure: A non-timeout exception during a read request. The rest
of the ERROR message body will be
<cl><received><blockfor><num_failures><data_present>
where:
<cl> is the [consistency] level of the query having triggered
the exception.
<received> is an [int] representing the number of nodes having
answered the request.
<blockfor> is an [int] representing the number of replicas whose
acknowledgement is required to achieve <cl>.
<num_failures> is an [int] representing the number of nodes that
experience a failure while executing the request.
<data_present> is a single byte. If its value is 0, it means
the replica that was asked for data had not
responded. Otherwise, the value is != 0.
0x1400 Function_failure: A (user defined) function failed during execution.
The rest of the ERROR message body will be
<keyspace><function><arg_types>
where:
<keyspace> is the keyspace [string] of the failed function
<function> is the name [string] of the failed function
<arg_types> [string list] one string for each argument type (as CQL type) of the failed function
0x1500 Write_failure: A non-timeout exception during a write request. The rest
of the ERROR message body will be
<cl><received><blockfor><num_failures><write_type>
where:
<cl> is the [consistency] level of the query having triggered
the exception.
<received> is an [int] representing the number of nodes having
answered the request.
<blockfor> is an [int] representing the number of replicas whose
acknowledgement is required to achieve <cl>.
<num_failures> is an [int] representing the number of nodes that
experience a failure while executing the request.
<writeType> is a [string] that describes the type of the write
that failed. The value of that string can be one
of:
- "SIMPLE": the write was a non-batched
non-counter write.
- "BATCH": the write was a (logged) batch write.
If this type is received, it means the batch log
has been successfully written (otherwise a
"BATCH_LOG" type would have been sent instead).
- "UNLOGGED_BATCH": the write was an unlogged
batch. No batch log write has been attempted.
- "COUNTER": the write was a counter write
(batched or not).
- "BATCH_LOG": the failure occurred during the
write to the batch log when a (logged) batch
write was requested.
- "CAS": the failure occurred during the Compare And Set write/update.
- "VIEW": the failure occurred when a write involves
VIEW update and failure to acquire local view(MV)
lock for key within timeout
- "CDC": the failure occurred when cdc_total_space is
exceeded when doing a write to data tracked by cdc.
0x2000 Syntax_error: The submitted query has a syntax error.
0x2100 Unauthorized: The logged user doesn't have the right to perform
the query.
0x2200 Invalid: The query is syntactically correct but invalid.
0x2300 Config_error: The query is invalid because of some configuration issue
0x2400 Already_exists: The query attempted to create a keyspace or a
table that was already existing. The rest of the ERROR message
body will be <ks><table> where:
<ks> is a [string] representing either the keyspace that
already exists, or the keyspace in which the table that
already exists is.
<table> is a [string] representing the name of the table that
already exists. If the query was attempting to create a
keyspace, <table> will be present but will be the empty
string.
0x2500 Unprepared: Can be thrown while a prepared statement tries to be
executed if the provided prepared statement ID is not known by
this host. The rest of the ERROR message body will be [short
bytes] representing the unknown ID.
10. Changes from v3
* Prepared responses (Section 4.2.5.4) now include partition-key bind indexes
* The format of "SCHEMA_CHANGE" events (Section 4.2.6) (and implicitly
"Schema_change" results (Section 4.2.5.5)) has been modified, and now includes
changes related to user defined functions and user defined aggregates.
* Read_failure error code was added.
* Function_failure error code was added.
* Add custom payload to frames for custom QueryHandler implementations (ignored by
Cassandra's standard QueryHandler)
* Add warnings to frames for responses for which the server generated a warning
during processing, which the client needs to address.
* Add the date and time data types
* Add the tinyint and smallint data types
* The <paging_state> returned in the v4 protocol is not compatible with the v3
protocol. In other words, a <paging_state> returned by a node using protocol v4
should not be used to query a node using protocol v3 (and vice-versa).
* Added THROW_ON_OVERLOAD startup option (Section 4.1.1).
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