CQL BINARY PROTOCOL v3 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 v2 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 opcode is defined Section 2.3 and the details of each corresponding message is described Section 4. The protocol distinguishes 2 types of frames: requests and responses. Requests are those frame sent by the clients to the server, response are the ones sent by the server. Note however that the protocol supports server pushes (events) so responses does not necessarily come right after a client request. Note to client implementors: clients library 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 remaining of the frame body in such cases. The reason is that this may allow to sometimes extend 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 indicate both the direction of the message (request or response) and the version of the protocol in use. The up-most bit of version is used to define the direction of the message: 0 indicates a request, 1 indicates a responses. This can be useful for protocol analyzers to distinguish the nature of the packet from the direction which it is moving. The rest of that byte is the protocol version (3 for the protocol defined in this document). In other words, for this version of the protocol, version will have one of: 0x03 Request frame for this protocol version 0x83 Response frame for this protocol version Please note that the while every message ship 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 describe the version 3 of the protocol. For the changes made since version 2, see Section 10. 2.2. flags Flags applying to this frame. The flags have the following meaning (described by the mask that allow to select 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 indicate the client requires tracing of the request. Note that not all requests support tracing. Currently, only QUERY, PREPARE and EXECUTE queries support tracing. Other requests will simply ignore the tracing flag if set. If a request support tracing and the tracing flag was 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. The rest of the body will then be the usual body corresponding to the response opcode. The rest of the 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 allow to deal with 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 id to these 3 requests allows the client to distinguish to which request an received answer respond 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 those implementation. 2.4. opcode An integer byte that distinguish 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 signed integer [long] A 8 bytes signed 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`. [short bytes] A [short] n, followed by n bytes if n >= 0. [option] A pair of where is a [short] representing the option id and depends on that option (and can be of size 0). The supported id (and the corresponding ) 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 correspondance: 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 where and are [string]. [string multimap] A [short] n, followed by n pair where is a [string] and is a [string list]. 4. Messages 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 message. The body is a [string map] of options. Possible options are: - "CQL_VERSION": the version of CQL to use. This option is mandatory and currenty, 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. 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 answer with this message. Those exchanges continue until the server accepts the authentication by sending a AUTH_SUCCESS message after a client AUTH_RESPONSE. It is however that client that initiate the exchange by 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 what 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: where is a [long string] representing the query and must be [[name_1]...[name_n]][][][][] where: - is the [consistency] level for the operation. - 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 there mask: 0x01: Values. In that case, a [short] followed by [bytes] values are provided. Those value 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 binded to. This is optional, and if not present, values will be binded by position. 0x02: Skip_metadata. If present, the Result Set returned as a response to that query (if any) will have the NO_METADATA flag (see Section 4.2.5.2). 0x04: Page_size. In that case, 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 present, should be present. is a [bytes] value that should have been returned in a result set (Section 4.2.5.2). If provided, the query will be executed but starting from a given paging state. This also to continue paging on a different node from the one it has been started (See Section 8 for more details). 0x10: With serial consistency. If present, should be present. is the [consistency] level for the serial phase of conditional updates. That consitency can only be either SERIAL or LOCAL_SERIAL and if not present, it defaults to SERIAL. This option will be ignored for anything else that a conditional update/insert. 0x20: With default timestamp. If present, should be present. is a [long] representing the default timestamp for the query in microseconds (negative values are discouraged but supported for backward compatibility reasons except for the smallest negative value (-2^63) that is forbidden). If provided, 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: where is the prepared query ID. It's the [short bytes] returned as a response to a PREPARE message. As for , it has the exact same definition than 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: ...[][] where: - is a [byte] indicating the type of batch to use: - If == 0, the batch will be "logged". This is equivalent to a normal CQL3 batch statement. - If == 1, the batch will be "unlogged". - If == 2, the batch will be a "counter" batch (and non-counter statements will be rejected). - is a [byte] whose bits define the options for this query and in particular influence the remainder of the message contains. It is similar to the from QUERY and EXECUTE methods, except that the 4 rightmost bits must always be 0 as their corresponding option do not make sense for Batch. A flag is set if the bit corresponding to its `mask` is set. Supported flags are, given there mask: 0x10: With serial consistency. If present, should be present. is the [consistency] level for the serial phase of conditional updates. That consitency can only be either SERIAL or LOCAL_SERIAL and if not present, it defaults to SERIAL. This option will be ignored for anything else that a conditional update/insert. 0x20: With default timestamp. If present, should be present. is a [long] representing the default timestamp for the query in microseconds. If provided, 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 must be preceded by a [string] 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]. - is a [short] indicating the number of following queries. - ... are the queries to execute. A must be of the form: []...[] where: - is a [byte] indicating whether the following query is a prepared one or not. value must be either 0 or 1. - depends on the value of . If == 0, it should be a [long string] query string (as in QUERY, the query string might contain bind markers). Otherwise (that is, if == 1), it should be a [short bytes] representing a prepared query ID. - is a [short] indicating the number (possibly 0) of following values. - is the optional name of the following . It must be present if and only if the 0x40 flag is provided for the batch. - is the [bytes] to use for bound variable i (of bound variable if the 0x40 flag is used). - is the [consistency] level for the operation. - is only present if the 0x10 flag is set. In that case, is the [consistency] level for the serial phase of conditional updates. That consitency can only be either SERIAL or LOCAL_SERIAL and if not present will defaults to SERIAL. This option will be ignored for anything else that a conditional update/insert. The server will respond with a RESULT message. 4.1.8. REGISTER Register this connection to receive some type of events. The body of the message is a [string list] representing the event types to register to. 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 informations (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, or after a successful CREDENTIALS message. The body of a READY message is empty. 4.2.3. AUTHENTICATE Indicates that the server require authentication, and which authentication mechanism to use. The authentication is SASL based and thus consists on 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 boostrapped by an initial client response. The details of that exchange (including how much challenge-response pair 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 body of a Rows result is: where: - is composed of: [][?...] where: - is an [int]. The bits of provides information on the formatting of the remaining informations. A flag is set if the bit corresponding to its `mask` is set. Supported flags are, given there mask: 0x0001 Global_tables_spec: if set, only one table spec (keyspace and table name) is provided as . If not set, is not present. 0x0002 Has_more_pages: indicates whether this is not the last page of results and more should be retrieve. If set, the will be present. The is a [bytes] value that should be used in QUERY/EXECUTE to continue paging and retrieve the remained of the result for this query (See Section 8 for more details). 0x0004 No_metadata: if set, the is only composed of these , the and optionally the (depending on the Has_more_pages flage) but no other information (so no nor ). This will only ever be the case if this was requested during the query (see QUERY and RESULT messages). - is an [int] representing the number of columns selected by the query this result is of. It defines the number of elements in and the number of element for each row in . - is present if the Global_tables_spec is set in . If present, it is composed of two [string] representing the (unique) keyspace name and table name the columns return are of. - specifies the columns returned in the query. There is such column specifications that are composed of: ()? The initial and are two [string] are only present if the Global_tables_spec flag is not set. The is a [string] and is an [option] that correspond 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 bind variable corresponding or the column name for the variable if it is "anonymous") and type of the corresponding result. The option for 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 full 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 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 ... where: - is a [string] representing the keyspace name this UDT is part of. - is a [string] representing the UDT name. - is a [short] reprensenting the number of fields of the UDT, and thus the number of pair following - is a [string] representing the name of the i_th field of the UDT. - is an [option] representing the type of the i_th field of the UDT. 0x0031 Tuple: the value is ... where is a [short] representing the number of value in the type, and are [option] representing the type of the i_th component of the tuple - is an [int] representing the number of rows present in this result. Those rows are serialized in the part. - is composed of ... where m is . Each is composed of ... where n is and where is a [bytes] representing the value returned for the jth column of the ith row. In other words, is composed of ( * ) [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 rest of the body of a Prepared result is: where: - is [short bytes] representing the prepared query ID. - is defined exactly as for a Rows RESULT (See section 4.2.5.2; you can however assume that the Has_more_pages flag is always off) and is the specification for the variable bound in this prepare statement. - is defined exactly as but correspond to the metadata for the resultSet that execute this query will yield. Note that 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. There is in fact never a guarantee that this will non-empty so client should protect themselves accordingly. The presence of this information is an optimization that allows to later execute the statement that has been prepared without requesting the metadata (Skip_metadata flag in EXECUTE). Clients can safely discard this metadata if they do not want to take advantage of that optimization. Note that prepared query ID return is global to the node on which the query has been prepared. It can be used on any connection to that node and this until the node is restarted (after which the query must be reprepared). 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: Please refer to the section 4.2.6 below for the meaning of those fields. Note that queries to create and drop an index are considered as change updating the table the index is on. 4.2.6. EVENT And event pushed by the server. A client will only receive events for the type it has REGISTER to. The body of an EVENT message will start by 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", "REMOVED_NODE", or "MOVED_NODE") followed by the address of the new/removed/moved 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 where: - is a [string] representing the type of changed involved. It will be one of "CREATED", "UPDATED" or "DROPPED". - is a [string] that can be one of "KEYSPACE", "TABLE" or "TYPE" and describes what has been modified ("TYPE" stands for modifications related to user types). - depends on the preceding . If is "KEYSPACE", then will be a single [string] representing the keyspace changed. Otherwise, if is "TABLE" or "TYPE", then 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 (so either the table name or the user type name). All EVENT message 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 advise to wait a short time before trying to connect to the node (1 seconds should be enough), otherwise they may experience a connection refusal at first. It is possible for the same event to be sent multiple times. Therefore, a client library should ignore the same event if it has already been notified of a change. 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 by an AUTH_RESPONSE message. 4.2.7. AUTH_SUCCESS Indicate 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 can be compressed (including the response to the STARTUP request). Frame do not have to be compressed however, even if compression has been agreed upon (a server may only compress frame 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 this version 2 of the protocol, the following compressions are available: - lz4 (https://code.google.com/p/lz4/). In that, note that the 4 first 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 avaivable on some installation. 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 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 "E<-scale>". In other words, " * 10 ^ (-1 * )". 6.6 double An eight-byte floating point number in the IEEE 754 binary64 format. 6.7 float An four-byte floating point number in the IEEE 754 binary32 format. 6.8 inet A 4 byte or 16 byte sequence denoting an IPv4 or IPv6 address, respectively. 6.9 int A four-byte two's complement integer. 6.10 list A [int] n indicating the number of elements in the list, followed by n elements. Each element is [bytes] representing the serialized value. 6.11 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. 6.12 set A [int] n indicating the number of elements in the set, followed by n elements. Each element is [bytes] representing the serialized value. 6.13 text A sequence of bytes conforming to the UTF-8 specifications. 6.14 timestamp An eight-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. 6.15 uuid A 16 byte sequence representing any valid UUID as defined by RFC 4122. 6.16 varchar An alias of the "text" type. 6.17 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. 6.18 timeuuid A 16 byte sequence representing a version 1 UUID as defined by RFC 4122. 6.19 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. Within a tuple, all data types should use the v3 protocol serialization format. 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. Within a user-defined type value, all data types should use the v3 protocol serialization format. 8. Result paging The protocol allows for paging the result of queries. For that, the QUERY and EXECUTE messages have a value that indicate the desired page size in CQL3 rows. If a positive value is provided for , the result set of the RESULT message returned for the query will contain at most the first rows of the query result. If that first page of result 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 value. In that case, the value should be used in a QUERY or EXECUTE message (that has the *same* query than 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 value is ignored. Note to client implementors: - While 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 is more result to fetch or not. Instead, they should always check the Has_more_pages flag (unless they did not enabled paging for the query obviously). Clients should also not assert that no result will have more than results. While the current implementation always respect the exact value of , we reserve ourselves the right to return slightly smaller or bigger pages in the future for performance reasons. 9. Error codes The supported error codes 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 Bad credentials: CREDENTIALS request failed because Cassandra did not accept the provided credentials. 0x1000 Unavailable exception. The rest of the ERROR message body will be where: is the [consistency] level of the query having triggered the exception. is an [int] representing the number of node that should be alive to respect is an [int] representing the number of replica that were known to be alive when the request has been processed (since an unavailable exception has been triggered, there will be < ) 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 where: is the [consistency] level of the query having triggered the exception. is an [int] representing the number of nodes having acknowledged the request. is an [int] representing the number of replica whose acknowledgement is required to achieve . is a [string] that describe the type of the write that timeouted. 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 send instead). - "UNLOGGED_BATCH": the write was an unlogged batch. Not batch log write has been attempted. - "COUNTER": the write was a counter write (batched or not). - "BATCH_LOG": the timeout occured during the write to the batch log when a (logged) batch write was requested. 0x1200 Read_timeout: Timeout exception during a read request. The rest of the ERROR message body will be where: is the [consistency] level of the query having triggered the exception. is an [int] representing the number of nodes having answered the request. is an [int] representing the number of replica whose response is required to achieve . Please note that it is possible to have >= if is false. And also in the (unlikely) case were is achieved but the coordinator node timeout while waiting for read-repair acknowledgement. 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. 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 where: is a [string] representing either the keyspace that already exists, or the keyspace in which the table that already exists is.
is a [string] representing the name of the table that already exists. If the query was attempting to create a keyspace,
will be present but will be the empty string. 0x2500 Unprepared: Can be thrown while a prepared statement tries to be executed if the provide 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 v2 * stream id is now 2 bytes long (a [short] value), so the header is now 1 byte longer (9 bytes total). * BATCH messages now have (like QUERY and EXECUTE) and a corresponding optional parameters (see Section 4.1.7). * User Defined Types and tuple types have to added to ResultSet metadata (see 4.2.5.2) and a new section on the serialization format of UDT and tuple values has been added to the documentation (Section 7). * The serialization format for collection has changed (both the collection size and the length of each argument is now 4 bytes long). See Section 6. * QUERY, EXECUTE and BATCH messages can now optionally provide the default timestamp for the query. As this feature is optionally enabled by clients, implementing it is at the discretion of the client. * QUERY and EXECUTE messages can now optionally provide the names for the values of the query. As this feature is optionally enabled by clients, implementing it is at the discretion of the client (Note that while the BATCH message has a flag for this, it actually doesn't work for BATCH, see Section 4.1.7 for details). * The format of "Schema_change" results (Section 4.2.5.5) and "SCHEMA_CHANGE" events (Section 4.2.6) has been modified, and now includes changes related to user types.