This section describes the detailed format of each message. Each can be sent
by either a frontend (F), a backend (B), or both (F & B).
AsciiRow (B)
Byte1('D')
Identifies the message as an ASCII data row.
(A prior RowDescription message defines the number of
fields in the row and their data types.)
Byten
A bit map with one bit for each field in the row. The 1st
field corresponds to bit 7 (MSB) of the 1st byte, the 2nd
field corresponds to bit 6 of the 1st byte, the 8th field
corresponds to bit 0 (LSB) of the 1st byte, the 9th field
corresponds to bit 7 of the 2nd byte, and so on. Each bit
is set if the value of the corresponding field is not NULL.
If the number of fields is not a multiple of 8, the remainder
of the last byte in the bit map is wasted.
Then, for each field with a non-NULL value, there is the following:
Int32
Specifies the size of the value of the field, including
this size.
Byten
Specifies the value of the field itself in ASCII
characters. n is the above
size minus 4.
There is no trailing zero-byte in the field data; the front
end must add one if it wants one.
AuthenticationOk (B)
Byte1('R')
Identifies the message as an authentication request.
Int32(0)
Specifies that the authentication was successful.
AuthenticationKerberosV4 (B)
Byte1('R')
Identifies the message as an authentication request.
Int32(1)
Specifies that Kerberos V4 authentication is required.
AuthenticationKerberosV5 (B)
Byte1('R')
Identifies the message as an authentication request.
Int32(2)
Specifies that Kerberos V5 authentication is required.
AuthenticationCleartextPassword (B)
Byte1('R')
Identifies the message as an authentication request.
Int32(3)
Specifies that a cleartext password is required.
AuthenticationCryptPassword (B)
Byte1('R')
Identifies the message as an authentication request.
Int32(4)
Specifies that a crypt()-encrypted password is required.
Byte2
The salt to use when encrypting the password.
AuthenticationMD5Password (B)
Byte1('R')
Identifies the message as an authentication request.
Int32(5)
Specifies that an MD5-encrypted password is required.
Byte4
The salt to use when encrypting the password.
AuthenticationSCMCredential (B)
Byte1('R')
Identifies the message as an authentication request.
Int32(6)
Specifies that an SCM credentials message is required.
BackendKeyData (B)
Byte1('K')
Identifies the message as cancellation key data.
The frontend must save these values if it wishes to be
able to issue CancelRequest messages later.
Int32
The process ID of this backend.
Int32
The secret key of this backend.
BinaryRow (B)
Byte1('B')
Identifies the message as a binary data row.
(A prior RowDescription message defines the number of
fields in the row and their data types.)
Byten
A bit map with one bit for each field in the row. The 1st
field corresponds to bit 7 (MSB) of the 1st byte, the 2nd
field corresponds to bit 6 of the 1st byte, the 8th field
corresponds to bit 0 (LSB) of the 1st byte, the 9th field
corresponds to bit 7 of the 2nd byte, and so on. Each bit
is set if the value of the corresponding field is not NULL.
If the number of fields is not a multiple of 8, the remainder
of the last byte in the bit map is wasted.
Then, for each field with a non-NULL value, there is the following:
Int32
Specifies the size of the value of the field, excluding
this size.
Byten
Specifies the value of the field itself in binary
format. n is the above size.
CancelRequest (F)
Int32(16)
The size of the packet in bytes.
Int32(80877102)
The cancel request code. The value is chosen to contain
1234 in the most significant 16 bits, and 5678 in the
least 16 significant bits. (To avoid confusion, this code
must not be the same as any protocol version number.)
Int32
The process ID of the target backend.
Int32
The secret key for the target backend.
CompletedResponse (B)
Byte1('C')
Identifies the message as a completed response.
String
The command tag. This is usually a single
word that identifies which SQL command was completed.
For an INSERT command, the tag is
INSERT oidrows, where
rows is the number of rows
inserted, and oid is the object ID
of the inserted row if rows is 1,
otherwise oid is 0.
For a DELETE command, the tag is
DELETE rows where
rows is the number of rows deleted.
For an UPDATE command, the tag is
UPDATE rows where
rows is the number of rows updated.
CopyDataRows (B & F)
This is a stream of rows where each row is terminated by a Byte1('\n').
This is then followed by the sequence Byte1('\\'), Byte1('.'),
Byte1('\n').
CopyInResponse (B)
Byte1('G')
Identifies the message as a Start Copy In response.
The frontend must now send a CopyDataRows message.
CopyOutResponse (B)
Byte1('H')
Identifies the message as a Start Copy Out response.
This message will be followed by a CopyDataRows message.
CursorResponse (B)
Byte1('P')
Identifies the message as a cursor response.
String
The name of the cursor. This will be "blank" if the cursor is
implicit.
EmptyQueryResponse (B)
Byte1('I')
Identifies the message as a response to an empty query string.
String("")
Unused.
ErrorResponse (B)
Byte1('E')
Identifies the message as an error.
String
The error message itself.
FunctionCall (F)
Byte1('F')
Identifies the message as a function call.
String("")
Unused.
Int32
Specifies the object ID of the function to call.
Int32
Specifies the number of arguments being supplied to the
function.
Then, for each argument, there is the following:
Int32
Specifies the size of the value of the argument,
excluding this size.
Byten
Specifies the value of the field itself in binary
format. n is the above size.
FunctionResultResponse (B)
Byte1('V')
Identifies the message as a function call result.
Byte1('G')
Specifies that a nonempty result was returned.
Int32
Specifies the size of the value of the result, excluding this
size.
Byten
Specifies the value of the result itself in binary format.
n is the above size.
Byte1('0')
Unused. (Strictly speaking, FunctionResultResponse and
FunctionVoidResponse are the same thing but with some optional
parts to the message.)
FunctionVoidResponse (B)
Byte1('V')
Identifies the message as a function call result.
Byte1('0')
Specifies that an empty result was returned.
NoticeResponse (B)
Byte1('N')
Identifies the message as a notice.
String
The notice message itself.
NotificationResponse (B)
Byte1('A')
Identifies the message as a notification response.
Int32
The process ID of the notifying backend process.
String
The name of the condition that the notify has been raised on.
PasswordPacket (F)
Int32
The size of the packet in bytes.
String
The password (encrypted, if requested).
Query (F)
Byte1('Q')
Identifies the message as a query.
String
The query string itself.
ReadyForQuery (B)
Byte1('Z')
Identifies the message type. ReadyForQuery is sent
whenever the backend is ready for a new query cycle.
RowDescription (B)
Byte1('T')
Identifies the message as a row description.
Int16
Specifies the number of fields in a row (may be zero).
Then, for each field, there is the following:
String
Specifies the field name.
Int32
Specifies the object ID of the field type.
Int16
Specifies the type size.
Int32
Specifies the type modifier.
SSLRequest (F)
Int32(8)
The size of the packet in bytes.
Int32(80877103)
The SSL request code. The value is chosen to contain
1234 in the most significant 16 bits, and 5679 in the
least 16 significant bits. (To avoid confusion, this code
must not be the same as any protocol version number.)
StartupPacket (F)
Int32(296)
The size of the packet in bytes.
Int32
The protocol version number. The most significant 16 bits are
the major version number. The least 16 significant bits are
the minor version number.
LimString64
The database name, defaults to the user name if empty.
LimString32
The user name.
LimString64
Any additional command line arguments to be passed to the
backend child process by the server.
LimString64
Unused.
LimString64
The optional tty the backend should use for debugging messages.
(Currently, this field is unsupported and ignored.)
