Re: Indexes mysteriously change to ON ONLY

I cheat by using sed to remove "ONLY ON " from the CREATE statements.

On 1/27/23 15:30, Rumpi Gravenstein wrote:
> Tom/Christophe  I now understand.  Thanks for the clear explanation.
>
> On Fri, Jan 27, 2023 at 4:16 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>
> Rumpi Gravenstein <rgravens(at)gmail(dot)com> writes:
> > We are using the pg_indexes view (indexdef) to retrieve the index
> > definition.
>
> Ah.
>
> > Are you saying that as a normal part of building an index, there are
> short
> > periods of time where the pg_indexes view will show the index with
> ON ONLY
> > specified?
>
> No, there's no "short periods", this is what it shows.  That's partly
> because the output is designed for pg_dump to use.  But there's
> a reasonably good argument for it anyway, which is that if you just
> say "create index" then that's effectively a macro for building the
> whole partitioned index set.  That pg_indexes entry is only about the
> top-level "virtual" index, and there are other entries for the leaf
> indexes.  For example,
>
> regression=# create table foo (f1 int primary key) partition by list (f1);
> CREATE TABLE
> regression=# create table foo_1 partition of foo for values in (1);
> CREATE TABLE
> regression=# create table foo_2 partition of foo for values in (2);
> CREATE TABLE
> regression=# select tablename,indexname,indexdef from pg_indexes where
> indexname like 'foo%';
>  tablename | indexname  |  indexdef
> -----------+------------+------------------------------------------------------------------
>  foo       | foo_pkey   | CREATE UNIQUE INDEX foo_pkey ON ONLY
> public.foo USING btree (f1)
>  foo_1     | foo_1_pkey | CREATE UNIQUE INDEX foo_1_pkey ON
> public.foo_1 USING btree (f1)
>  foo_2     | foo_2_pkey | CREATE UNIQUE INDEX foo_2_pkey ON
> public.foo_2 USING btree (f1)
> (3 rows)
>
> If you wanted to reconstruct this from individual parts, as pg_dump does,
> you'd issue those commands and then connect them together with ATTACH
> PARTITION commands.
>
>                         regards, tom lane
>
>
>
> --
> Rumpi Gravenstein

--
Born in Arizona, moved to Babylonia.