COPY to question

Rich Shepard <rshepard@appl-ecosys.com> writes:

Running -9.6.1. I have a database created and owned by me, but cannot copy
a table to my home directory. Postgres tells me it cannot write to that
directory. The only way to copy tables to files is by doing so as the
superuser (postgres).

Why is this, and can I change something so I, as a user, can copy tables
directly to ~/?

Use psql's \copy instead.

regards, tom lane

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On Tue, 17 Jan 2017, Tom Lane wrote:

Use psql's \copy instead.

Thanks, Tom.

Rich

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2017-01-17 19:23 GMT+01:00 Rich Shepard <rshepard@appl-ecosys.com>:

Running -9.6.1. I have a database created and owned by me, but cannot
copy
a table to my home directory. Postgres tells me it cannot write to that
directory. The only way to copy tables to files is by doing so as the
superuser (postgres).

Why is this, and can I change something so I, as a user, can copy tables
directly to ~/?

You cannot to use server side COPY for writing directly to client side
directory.

If you use psql console, and there is client side backslash COPY statement.
There you can write anywhere on client side, where you have a access.

\COPY table TO ~/xxx.dta

is valid there.

Regards

Pavel

On Jan 17, 2017, at 10:23 AM, Rich Shepard <rshepard@appl-ecosys.com> wrote:

Running -9.6.1. I have a database created and owned by me, but cannot copy
a table to my home directory. Postgres tells me it cannot write to that
directory. The only way to copy tables to files is by doing so as the
superuser (postgres).

Why is this, and can I change something so I, as a user, can copy tables
directly to ~/?

You can use "\copy" from psql to do the same thing as the SQL copy command,
but writing files as the user running psql, rather than the postgresql superuser
role. That's probably what you need.

Cheers,
Steve

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On Tue, Jan 17, 2017 at 11:23 AM, Rich Shepard <rshepard@appl-ecosys.com>
wrote:

Running -9.6.1. I have a database created and owned by me, but cannot
copy
a table to my home directory. Postgres tells me it cannot write to that
directory. The only way to copy tables to files is by doing so as the
superuser (postgres).

​When you ask the server to access the filesystem (e.g., via SQL COPY) it
does so on your behalf but using its own operating system user​. It makes
no attempt to match the role that you are logged in as with a corresponding
operating system user.

As Tom noted if you want to do things as "you" and not "the server" you
need to perform them within a client (psql being the main one). In psql
you can get COPY functionality via the \copy meta-command. The server
sends its output to the client which then redirects it to some path on the
local machine. If you run psql on the server you can access a home
directory on the server.

Why is this

​COPY naming a file or command is only allowed to database superusers,
since it allows reading or writing any file that the server has privileges
to access.​

See above for why its the sever's privileges that matter.

David J.

On Tue, Jan 17, 2017 at 10:23 AM, Rich Shepard <rshepard@appl-ecosys.com>
wrote:

Running -9.6.1. I have a database created and owned by me, but cannot
copy
a table to my home directory. Postgres tells me it cannot write to that
directory. The only way to copy tables to files is by doing so as the
superuser (postgres).

Why is this, and can I change something so I, as a user, can copy tables
directly to ~/?

To add to the other answers, more info is available at

https://www.postgresql.org/docs/current/static/app-psql.html#APP-PSQL-META-COMMANDS-COPY
and https://wiki.postgresql.org/wiki/COPY

Note that you can invoke SQL COPY to STDOUT as in: COPY (some arbitrary
query) TO STDOUT;

You would either pipe/redirect the output of psql as desired or use the
"\o" within psql to reroute the output to a file or pipe to a program, for
example, output to a CSV using a pipe as the delimiter and double-quote as
the quote character but change all "ma" to "pa" and put into myoutput.txt

\o | sed s/ma/pa/g > myoutput.txt
copy (some query) to stdout csv header delimiter '|' quote '"';
\o

Cheers,
Steve