Difference between copy and \copy commands in postgresql

Question

To transfer data between a file and a table in postgresql there are two options

COPY my_table FROM '/Users/user/Downloads/test.csv' DELIMITER ',' CSV HEADER;

Or

\COPY my_table FROM '/Users/user/Downloads/test.csv' DELIMITER ',' CSV HEADER;

My question is what is the difference between the two and which one is faster?

Answer 1

The COPY command is executed fully on server side - input/output is related to server side streams. But these streams can be redirected to client side - when you run COPY in a pre-configured environment. \COPY is this case.

\COPY is psql's commands - it can be executed only from psql and it prepares internal environment for a possible read/write from client side streams, and it execute COPY commands.

So difference between COPY and \COPY is minimal. \COPY is COPY executed in different configuration for a possible read/write data from client. The performance should be same - \COPY can be a little bit slower due to network overhead (it is clear), but it should not be significant. In this case the communication protocol should be effective.