Re: [HACKERS] New partitioning - some feedback

Hi Mark,

On 2017/07/07 9:02, Mark Kirkwood wrote:
> I've been trying out the new partitioning in version 10. Firstly, I must
> say this is excellent - so much nicer than the old inheritance based method!

Thanks. :)

> My only niggle is the display of partitioned tables via \d etc. e.g:
>
> part=# \d
>                 List of relations
>  Schema |         Name         | Type  |  Owner
> --------+----------------------+-------+----------
>  public | date_fact            | table | postgres
>  public | date_fact_201705     | table | postgres
>  public | date_fact_201706     | table | postgres
>  public | date_fact_20170601   | table | postgres
>  public | date_fact_2017060100 | table | postgres
>  public | date_fact_201707     | table | postgres
>  public | date_fact_rest       | table | postgres
> (7 rows)
> 
> Now it can be inferred from the names that date_fact is a partitioned
> table and the various date_fact_dddd are its partitions - but \d is not
> providing any hints of this. The more detailed individual describe is fine:
> 
> part=# \d date_fact
>                       Table "public.date_fact"
>  Column |           Type           | Collation | Nullable | Default
> --------+--------------------------+-----------+----------+---------
>  id     | integer                  |           | not null |
>  dte    | timestamp with time zone |           | not null |
>  val    | integer                  |           | not null |
> Partition key: RANGE (dte)
> Number of partitions: 6 (Use \d+ to list them.)
> 
> I'd prefer *not* to see a table and its partitions all intermixed in the
> same display (especially with nothing indicating which are partitions) -
> as this will make for unwieldy long lists when tables have many
> partitions. Also it would be good if the 'main' partitioned table and its
> 'partitions' showed up as a different type in some way.
> I note the they do in pg_class:
> 
> part=# SELECT relname,relkind,relispartition FROM pg_class WHERE relname
> LIKE 'date_fact%';
>        relname        | relkind | relispartition
> ----------------------+---------+----------------
>  date_fact            | p       | f
>  date_fact_201705     | r       | t
>  date_fact_201706     | r       | t
>  date_fact_20170601   | r       | t
>  date_fact_2017060100 | r       | t
>  date_fact_201707     | r       | t
>  date_fact_rest       | r       | t
> (7 rows)
> 
> ...so it looks to be possible to hide the partitions from the main display
> and/or mark them as such. Now I realize that making this comment now that
> beta is out is a bit annoying - apologies, but I think seeing a huge list
> of 'tables' is going to make \d frustrating for folk doing partitioning.

Someone complained about this awhile back [1].  And then it came up again
[2], where Noah appeared to take a stance that partitions should be
visible in views / output of commands that list "tables".

Although I too tend to prefer not filling up the \d output space by
listing partitions (pg_class.relispartition = true relations), there
wasn't perhaps enough push for creating a patch for that.  If some
committer is willing to consider such a patch, I can make one.

Thanks,
Amit

[1]
https://www.postgresql.org/message-id/CAM-w4HOZ5fPS7GoCTTrW42q01%2BwPrOWFCnr9H0iDyVTZP2H1CA%40mail.gmail.com

[2]
https://www.postgresql.org/message-id/20170406070227.GA2741046%40tornado.leadboat.com