Re: list of extended statistics on psql

Hi Julien and Pavel!

>> How about using \dX rather than \dz?
> 
> Thanks for your suggestion!
> I'll replace it if I got consensus. :-D

>> How about using \dX rather than \dz?
>
>Thanks for your suggestion!
>I'll replace it if I got consensus. :-D


I re-read a help message of \d* commands and realized it's better to
use "\dX".
There are already cases where the commands differ due to differences
in case, so I did the same way. Please find attached patch. :-D
  
For example:
==========
   \da[S]  [PATTERN]      list aggregates
   \dA[+]  [PATTERN]      list access methods
==========

Attached patch uses "\dX" instead of "\dz":
==========
   \dx[+]  [PATTERN]      list extensions
   \dX     [PATTERN]      list extended statistics
==========

Results of regress test of the feature are the following:
==========
-- check printing info about extended statistics
create table t1 (a int, b int);
create statistics stts_1 (dependencies) on a, b from t1;
create statistics stts_2 (dependencies, ndistinct) on a, b from t1;
create statistics stts_3 (dependencies, ndistinct, mcv) on a, b from t1;
create table t2 (a int, b int, c int);
create statistics stts_4 on b, c from t2;
create table hoge (col1 int, col2 int, col3 int);
create statistics stts_hoge on col1, col2, col3 from hoge;

\dX
                           List of extended statistics
  Schema | Table |   Name    |     Columns      | Ndistinct | Dependencies | MCV
--------+-------+-----------+------------------+-----------+--------------+-----
  public | hoge  | stts_hoge | col1, col2, col3 | t         | t            | t
  public | t1    | stts_1    | a, b             | f         | t            | f
  public | t1    | stts_2    | a, b             | t         | t            | f
  public | t1    | stts_3    | a, b             | t         | t            | t
  public | t2    | stts_4    | b, c             | t         | t            | t
(5 rows)

\dX stts_?
                     List of extended statistics
  Schema | Table |  Name  | Columns | Ndistinct | Dependencies | MCV
--------+-------+--------+---------+-----------+--------------+-----
  public | t1    | stts_1 | a, b    | f         | t            | f
  public | t1    | stts_2 | a, b    | t         | t            | f
  public | t1    | stts_3 | a, b    | t         | t            | t
  public | t2    | stts_4 | b, c    | t         | t            | t
(4 rows)

\dX *hoge
                           List of extended statistics
  Schema | Table |   Name    |     Columns      | Ndistinct | Dependencies | MCV
--------+-------+-----------+------------------+-----------+--------------+-----
  public | hoge  | stts_hoge | col1, col2, col3 | t         | t            | t
(1 row)
==========


Thanks,
Tatsuro Yamada