psycopg2.ProgrammingError: syntax error at or near "\"

Question

I have a python module which copy data from a table to a file.Im using postgresql as database server. COPY is the command is to be used to do the above action.

However in a blog (http://grokbase.com/t/postgresql/pgsql-general/058tagtped/about-error-must-be-superuser-to-copy-to-or-from-a-file) it states that, You can use \copy in 'psql' on the client side, but you have to be a superuser to do COPY on the server side, for security reasons. So I used \copy command. When I try to execute the below method, it results in error as

psycopg2.ProgrammingError: syntax error at or near "\" LINE 1: \copy

I can't find why its throwing error. can someone help me out?

def process():
     query="\copy %s TO %s"%('test_table', 'test_file.txt')

     @env.with_transaction()
     def do_execute(db):
         cursor = db.cursor()
         cursor.execute(query)

do_execute is a database wrapper, which creates connection and executes the query.

Answer 1

\ is an escape in Python strings, so your string contains the escape \c. However \c is an invalid escape in Python, and Python leaves invalid escapes unchanged, so "\copy" is just \copy. (Thus @tiziano's answer is misleading).

>>> print "\c"
\c

The real problem is that \copy is a psql command, not a server side PostgreSQL command. You can't use it with a client other than psql. You must instead use the psycopg2 support for COPY to do it via your client driver.