patch: autocomplete for functions

On sön, 2012-02-19 at 20:10 +0100, Pavel Stehule wrote:

I found so this extremely simple patch should be useful.

It helps for pattern SELECT fx();

Isn't that just a subset of what I had proposed?

http://archives.postgresql.org/message-id/1328820579.11241.4.camel@vanquo.pezone.net

There was thread about it.

Which thread was that?

2012/3/15 Peter Eisentraut <peter_e@gmx.net>:

On sön, 2012-02-19 at 20:10 +0100, Pavel Stehule wrote:

I found so this extremely simple patch should be useful.

It helps for pattern SELECT fx();

Isn't that just a subset of what I had proposed?

http://archives.postgresql.org/message-id/1328820579.11241.4.camel@vanquo.pezone.net

There was thread about it.

Which thread was that?

probably yours :)

Regards

Pavel

Excerpts from Peter Eisentraut's message of jue mar 15 16:25:53 -0300 2012:

On sön, 2012-02-19 at 20:10 +0100, Pavel Stehule wrote:

I found so this extremely simple patch should be useful.

It helps for pattern SELECT fx();

Isn't that just a subset of what I had proposed?

http://archives.postgresql.org/message-id/1328820579.11241.4.camel@vanquo.pezone.net

So do you intend to commit your patch?

--
Álvaro Herrera <alvherre@commandprompt.com>
The PostgreSQL Company - Command Prompt, Inc.
PostgreSQL Replication, Consulting, Custom Development, 24x7 support

On tor, 2012-03-15 at 16:36 -0300, Alvaro Herrera wrote:

Excerpts from Peter Eisentraut's message of jue mar 15 16:25:53 -0300 2012:

On sön, 2012-02-19 at 20:10 +0100, Pavel Stehule wrote:

I found so this extremely simple patch should be useful.

It helps for pattern SELECT fx();

Isn't that just a subset of what I had proposed?

http://archives.postgresql.org/message-id/1328820579.11241.4.camel@vanquo.pezone.net

So do you intend to commit your patch?

Well, there was quite a bit of discussion about it, but it appears that
most concerns were addressed at the end. So yes, I guess, unless
someone wants further discussion.

Peter Eisentraut <peter_e@gmx.net> writes:

On tor, 2012-03-15 at 16:36 -0300, Alvaro Herrera wrote:

Excerpts from Peter Eisentraut's message of jue mar 15 16:25:53 -0300 2012:

Isn't that just a subset of what I had proposed?
http://archives.postgresql.org/message-id/1328820579.11241.4.camel@vanquo.pezone.net

So do you intend to commit your patch?

Well, there was quite a bit of discussion about it, but it appears that
most concerns were addressed at the end. So yes, I guess, unless
someone wants further discussion.

I'm a bit concerned about whether that's actually going to be useful.
A quick check shows that in the regression database, the proposed patch
produces 3246 possible completions, which suggests that by the time you
get down to a unique match you're going to have typed most of the name
anyway.

BTW, you should at least exclude dropped columns, I think.

regards, tom lane

On fre, 2012-03-16 at 13:47 -0400, Tom Lane wrote:

I'm a bit concerned about whether that's actually going to be useful.
A quick check shows that in the regression database, the proposed patch
produces 3246 possible completions, which suggests that by the time you
get down to a unique match you're going to have typed most of the name
anyway.

Well, the regression test database is not really an example of real-life
object naming, I think. I tried this out on a couple of real databases
and found it quite handy.

BTW, you should at least exclude dropped columns, I think.

Yes.

Peter Eisentraut <peter_e@gmx.net> writes:

On fre, 2012-03-16 at 13:47 -0400, Tom Lane wrote:

I'm a bit concerned about whether that's actually going to be useful.
A quick check shows that in the regression database, the proposed patch
produces 3246 possible completions, which suggests that by the time you
get down to a unique match you're going to have typed most of the name
anyway.

Well, the regression test database is not really an example of real-life
object naming, I think.

Perhaps not, but a solid 2000 of those names are from the system-created
entries in pg_proc, and the regression DB doesn't have an especially
large number of tables either. I doubt that real DBs are likely to have
materially fewer completions.

This connects somewhat to the discussions we've had in the past about
trying to get not-intended-for-public-use functions out of the standard
search path. Not that you want to put a full visibility check into the
tab-completion query, but if it could simply exclude a "pg_private"
namespace, that probably wouldn't be too expensive.

regards, tom lane

Excerpts from Tom Lane's message of lun mar 19 16:53:49 -0300 2012:

This connects somewhat to the discussions we've had in the past about
trying to get not-intended-for-public-use functions out of the standard
search path. Not that you want to put a full visibility check into the
tab-completion query,

I'm rather of the contrary opinion -- surely if we're going to complete
function names, we should only complete those that are in schemas in the
path; similarly for column names. (BTW I didn't check but does this
completion work if I schema-qualify a column name?)

but if it could simply exclude a "pg_private"
namespace, that probably wouldn't be too expensive.

+1

--
Álvaro Herrera <alvherre@commandprompt.com>
The PostgreSQL Company - Command Prompt, Inc.
PostgreSQL Replication, Consulting, Custom Development, 24x7 support

On mån, 2012-03-19 at 15:53 -0400, Tom Lane wrote:

This connects somewhat to the discussions we've had in the past about
trying to get not-intended-for-public-use functions out of the
standard search path. Not that you want to put a full visibility
check into the tab-completion query, but if it could simply exclude a
"pg_private" namespace, that probably wouldn't be too expensive.

I wonder if this could be worked out using pg_depend. For example, give
me all functions that are not referenced by some object in pg_catalog.

On Sun, Feb 19, 2012 at 12:10 PM, Pavel Stehule <pavel.stehule@gmail.com> wrote:

Hello

I found so this extremely simple patch should be useful.

It helps for pattern SELECT fx();

There was thread about it.

Hi Pavel,
I signed up to be reviewer for this patch, and finally got around to
taking a look. This thread, and the thread about Peter's earlier patch
along the same lines have gotten a bit muddled, so allow me some recap
for my own sanity.

The first point to be addressed, is that Pavel's patch is basically a
subset of Peter's earlier[1]http://archives.postgresql.org/message-id/1328820579.11241.4.camel%40vanquo.pezone.net patch. Pavel's patch autocompletes

SELECT <TAB>

with possible function names. Peter's patch autocompletes both
possible column names and possible function names. So, which version,
if any, would we want? Both Tom[2]http://archives.postgresql.org/message-id/7745.1328855069%40sss.pgh.pa.us and depesz[3]http://www.depesz.com/2011/07/08/wish-list-for-psql/ have asked for column
names to be autocompleted if we're going to go down this road, and I
personally would find completion of column names handy. Others [5]http://archives.postgresql.org/message-id/CA%2BTgmoY7wRGgBbFhKwfASqrNOPwZwCjfm1AhL82769Xx-SyduA%40mail.gmail.com[6]http://archives.postgresql.org/message-id/20120210140637.GB19783%40ldn-qws-004.delacy.com
have asked for function names to be (also?) autocompleted here, so it
seems reasonable that we'd want to include both.

I counted two general objections to Peter's patch in these threads, namely:

1.) Complaints about the tab-completion not covering all cases,
possibly leading to user frustration at our inconsistency. [2]http://archives.postgresql.org/message-id/7745.1328855069%40sss.pgh.pa.us [4]http://archives.postgresql.org/message-id/13612.1328887227%40sss.pgh.pa.us
2.) Concerns that the tab-completion wouldn't be useful given how
many results we'd have from system columns and functions [7]http://archives.postgresql.org/message-id/9966.1331920074%40sss.pgh.pa.us

I do agree these are two legitimate concerns. However, for #1, our
tab-completion is and has always been incomplete. I take the basic
goal of the tab-completion machinery to be "offer a suggestion when
we're pretty sure we know what the user wants, otherwise stay quiet".
There are all sorts of places where our reliance on inspecting back
only a few words into the current line and not having a true command
parser prevents us from being able to make tab-completion guesses, but
that's been accepted so far, and I don't think it's fair to raise the
bar for this patch.

Re: concern #2, Tom complained about there being a bunch of possible
column and function completions in the regression test database. That
may be true, but if you look at this slightly-modified version of the
query Peter's patch proposes:

SELECT substring(name, 1, 3) AS sub, COUNT(*)
FROM (
SELECT attname FROM pg_attribute WHERE NOT attisdropped
UNION
SELECT proname || '(' FROM pg_proc p WHERE
pg_catalog.pg_function_is_visible(p.oid)) t (name)
GROUP BY sub ORDER BY COUNT(*) DESC;

I count only 384 distinct 3-length prefixes in an empty database,
thanks to many built-in columns and functions sharing the same prefix
(e.g. "int" or "pg_"). Obviously, there is plenty of room left for
3-length prefixes, out of the 27^3 or more possibilities. In some
casual mucking around in my own databases, I found the
column-completion rather useful, and typing 3 characters of a
column-name to be sufficient to give matches which were at least
non-builtin attributes, and often a single unique match.

There were some ideas down-thread about how we might filter out some
of the noise in these completions, which would be interesting. I'd be
happy with the patch as-is though, modulo the attisdropped and
pg_function_is_visible() tweaks to the query.

Josh

[1]: http://archives.postgresql.org/message-id/1328820579.11241.4.camel%40vanquo.pezone.net
[2]: http://archives.postgresql.org/message-id/7745.1328855069%40sss.pgh.pa.us
[3]: http://www.depesz.com/2011/07/08/wish-list-for-psql/
[4]: http://archives.postgresql.org/message-id/13612.1328887227%40sss.pgh.pa.us
[5]: http://archives.postgresql.org/message-id/CA%2BTgmoY7wRGgBbFhKwfASqrNOPwZwCjfm1AhL82769Xx-SyduA%40mail.gmail.com
[6]: http://archives.postgresql.org/message-id/20120210140637.GB19783%40ldn-qws-004.delacy.com
[7]: http://archives.postgresql.org/message-id/9966.1331920074%40sss.pgh.pa.us

On Mon, Mar 19, 2012 at 1:01 PM, Alvaro Herrera
<alvherre@commandprompt.com> wrote:

I'm rather of the contrary opinion -- surely if we're going to complete
function names, we should only complete those that are in schemas in the
path; similarly for column names.

I think it makes sense to only include currently-visible functions,
but *not* only columns from currently visible tables, since we won't
know yet whether the user intends to schema-qualify the table name.

 (BTW I didn't check but does this
completion work if I schema-qualify a column name?)

Peter's proposed tab-completion only kicks in for the column-name
itself. Keep in mind, the user might be trying to enter:
SELECT schema.table.column ...
SELECT table.column ...
SELECT table_alias.column ...
SELECT column ...

and presumably want to tab-complete the second token somehow. I'm a
bit leery about trying to tab-complete those first two, and the third
is right out. Just having the fourth would make me happy.

Josh