proposal: psql \setfileref

Hi

I propose a new type of psql variables - file references. The content of
file reference is specified by referenced file. It allows simple inserting
large data without necessity of manual escaping or using LO api.

When I wrote the patch, I used parametrized queries for these data instead
escaped strings - the code is not much bigger, and the error messages are
much more friendly if query is not bloated by bigger content. The text mode
is used only - when escaping is not required, then content is implicitly
transformed to bytea. By default the content of file is bytea. When use
requires escaping, then he enforces text escaping - because it has sense
only for text type.

postgres=# \setfileref a ~/test2.xml
postgres=# \setfileref b ~/avatar.gif
postgres=# insert into test values(convert_from(:a, 'latin2')::xml, :b); --
xml is passed as bytea
postgres=# insert into test values(:'a', :b); -- xml is passed via unknown
text value

The content of file reference variables is not persistent in memory.

Comments, notes?

Regards

Pavel