postgresql copy 消息

Posted 2021-09-07 黑暗森林

简单查询两个特殊的copy的返回值
https://www.postgresql.org/do...

CopyInResponse
The backend is ready to copy data from the frontend to a table; see Section 52.2.5.

CopyOutResponse
The backend is ready to copy data from a table to the frontend; see Section 52.2.5.

copy 相关消息

CommandComplete (B)
Byte1(\'C\')
Identifies the message as a command-completed response.

其中：String
For a COPY command, the tag is COPY rows where rows is the number of rows copied. (Note: the row count appears only in PostgreSQL 8.2 and later.)


CopyData (F & B)
Byte1(\'d\')
Identifies the message as COPY data.

CopyDone (F & B)
Byte1(\'c\')
Identifies the message as a COPY-complete indicator.

CopyFail (F)
Byte1(\'f\')
Identifies the message as a COPY-failure indicator.

CopyInResponse (B)
Byte1(\'G\')
Identifies the message as a Start Copy In response. The frontend must now send copy-in data (if not prepared to do so, send a CopyFail message).

CopyOutResponse (B)
Byte1(\'H\')
Identifies the message as a Start Copy Out response. This message will be followed by copy-out data.

CopyBothResponse (B)
Byte1(\'W\')
Identifies the message as a Start Copy Both response. This message is used only for Streaming Replication.

copy to file

postgres=# copy (select * from t1 ) to \'/tmp/t1.csv\';
COPY 5

copy from stdin

postgres=# copy t1 from stdin  (DELIMITER \'|\');
Enter data to be copied followed by a newline.
End with a backslash and a period on a line by itself, or an EOF signal.
>> 23|gg
>> 24|qq
>> 25|tt
>> COPY 3

copy to stdout

postgres=# copy t1 to STDOUT (DELIMITER \'|\');;
23|gg
24|qq
25|tt