SQLi[postgres] mode and passing tabs to psql

[rwc9u]

I'd like to figure a way to harness the completion functionality that
the psql client provides, and use that from within the emacs sqli mode
for postgres. If I run psql from the bash prompt then when I hit tab
twice I get completions for either sql keywords or table names
depending on the location of my cursor.

When I try to do this from within the sqli mode I can't figure out the
way to pass the tabs to the underlying process. I am assuming if I can
get this to work then I could write some sort of output filter to
provide a completions list.
Any ideas or modes to point me at that do something similar.

Thanks,

Rob