Re: Add missing tab completion for ALTER TABLE ADD COLUMN IF NOT EXISTS

Hi Kirill,

I looked through your patches. First of all, please note that TAB
completion doesn't have to complete all valid grammatical
constructions. See the comment on the top of tab-complete.in.c:

 * This file implements a somewhat more sophisticated readline "TAB
 * completion" in psql. It is not intended to be AI, to replace
 * learning SQL, or to relieve you from thinking about what you're
 * doing. Also it does not always give you all the syntactically legal
 * completions, only those that are the most common or the ones that
 * the programmer felt most like implementing.

Considering this, I don't think 0001 should be accepted as is. Neither
"IF NOT EXIST" nor "IF EXISTS" appears anywhere in tab-complete.in.c.
Adding it for the only "ALTER TABLE ... ADD COLUMN" case doesn't seem
right. Adding it everywhere looks like lots of work of questionable
utility.

0003 looks good to me. Considering that we already have a completion of
"CREATE TEMP TABLE ... USING" with table access methods, completion of
"CREATE TABLE ..." with USING seems reasonable. It’s strange we didn’t
have this before. Good catch!

I can't judge if 0002 adds useful completion cases, but I noticed that
you add completion of "DROP/ADD ATTRIBUTE ..." with CASCADE/RESRTICT
while ignoring "ALTER/RENAME ATTRIBUTE ..." that also can be followed
by CASCADE/RESRTICT according to the documentation. Is it intentional?

Best regards,
Karina Litskevich
Postgres Professional: http://postgrespro.com/