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From: SATYANARAYANA NARLAPURAM <satyanarlapuram@gmail.com>
Date: Thu, 23 Apr 2026 00:39:01 -0700
Message-ID: 
 <CAHg+QDdYq0NNF2ueLd1Hvn2njtJL2-MONd-=6REM6_4fHRTnhQ@mail.gmail.com>
Subject: Re: [Patch] Block ALTER TABLE RENAME COLUMN when column is used by
 property graph
To: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
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Hi

On Thu, Apr 23, 2026 at 12:33=E2=80=AFAM Ashutosh Bapat <
ashutosh.bapat.oss@gmail.com> wrote:

> On Thu, Apr 23, 2026 at 12:23=E2=80=AFPM SATYANARAYANA NARLAPURAM
> <satyanarlapuram@gmail.com> wrote:
> >
> > Hi hackers,
> >
> > When a table column is referenced by a property graph, the property
> > name stored in pg_propgraph_property.pgpname would become stale after
> > a column rename.  This caused GRAPH_TABLE queries to fail with the new
> > column name ("property does not exist") while the old (dead) name
> > continued to work.  pg_get_propgraphdef() would also emit confusing
> > output like "new_col AS old_col".
>
> This behaviour is inline with the behaviour of view.
>
> #create view vt as select a from t1;
> CREATE VIEW
> #\d+ vt
>                              View "public.vt"
>  Column |  Type   | Collation | Nullable | Default | Storage | Descriptio=
n
> --------+---------+-----------+----------+---------+---------+-----------=
--
>  a      | integer |           |          |         | plain   |
> View definition:
>  SELECT a
>    FROM t1;
>
> #alter table t1 rename column a TO aa;
> ALTER TABLE
> #\d+ vt
>                              View "public.vt"
>  Column |  Type   | Collation | Nullable | Default | Storage | Descriptio=
n
> --------+---------+-----------+----------+---------+---------+-----------=
--
>  a      | integer |           |          |         | plain   |
> View definition:
>  SELECT aa AS a
>    FROM t1;
>
> Name of the property is derived from the name of the column it
> references if the property name is not specified at the time of
> creating the property. But these two are different. Changing column
> name can not be expected to change the property name automatically. If
> two elements have the same label, the set of property names associated
> with that label is expected to be the same for those two elements as
> well.


Ashutosh, should we document this or it is a well known fact and not
needed? Asking in the context of Graphs, not views.


Thanks,
Satya

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<div dir=3D"auto">Hi</div><div><br><div class=3D"gmail_quote gmail_quote_co=
ntainer"><div dir=3D"ltr" class=3D"gmail_attr">On Thu, Apr 23, 2026 at 12:3=
3=E2=80=AFAM Ashutosh Bapat &lt;<a href=3D"mailto:ashutosh.bapat.oss@gmail.=
com">ashutosh.bapat.oss@gmail.com</a>&gt; wrote:<br></div><blockquote class=
=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid rg=
b(204,204,204);padding-left:1ex">On Thu, Apr 23, 2026 at 12:23=E2=80=AFPM S=
ATYANARAYANA NARLAPURAM<br>
&lt;<a href=3D"mailto:satyanarlapuram@gmail.com" target=3D"_blank">satyanar=
lapuram@gmail.com</a>&gt; wrote:<br>
&gt;<br>
&gt; Hi hackers,<br>
&gt;<br>
&gt; When a table column is referenced by a property graph, the property<br=
>
&gt; name stored in pg_propgraph_property.pgpname would become stale after<=
br>
&gt; a column rename.=C2=A0 This caused GRAPH_TABLE queries to fail with th=
e new<br>
&gt; column name (&quot;property does not exist&quot;) while the old (dead)=
 name<br>
&gt; continued to work.=C2=A0 pg_get_propgraphdef() would also emit confusi=
ng<br>
&gt; output like &quot;new_col AS old_col&quot;.<br>
<br>
This behaviour is inline with the behaviour of view.<br>
<br>
#create view vt as select a from t1;<br>
CREATE VIEW<br>
#\d+ vt<br>
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=
=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0View &quot;public.vt&quot;<br>
=C2=A0Column |=C2=A0 Type=C2=A0 =C2=A0| Collation | Nullable | Default | St=
orage | Description<br>
--------+---------+-----------+----------+---------+---------+-------------=
<br>
=C2=A0a=C2=A0 =C2=A0 =C2=A0 | integer |=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =
=C2=A0|=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 |=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=
=A0| plain=C2=A0 =C2=A0|<br>
View definition:<br>
=C2=A0SELECT a<br>
=C2=A0 =C2=A0FROM t1;<br>
<br>
#alter table t1 rename column a TO aa;<br>
ALTER TABLE<br>
#\d+ vt<br>
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=
=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0View &quot;public.vt&quot;<br>
=C2=A0Column |=C2=A0 Type=C2=A0 =C2=A0| Collation | Nullable | Default | St=
orage | Description<br>
--------+---------+-----------+----------+---------+---------+-------------=
<br>
=C2=A0a=C2=A0 =C2=A0 =C2=A0 | integer |=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =
=C2=A0|=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 |=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=
=A0| plain=C2=A0 =C2=A0|<br>
View definition:<br>
=C2=A0SELECT aa AS a<br>
=C2=A0 =C2=A0FROM t1;<br>
<br>
Name of the property is derived from the name of the column it<br>
references if the property name is not specified at the time of<br>
creating the property. But these two are different. Changing column<br>
name can not be expected to change the property name automatically. If<br>
two elements have the same label, the set of property names associated<br>
with that label is expected to be the same for those two elements as<br>
well.</blockquote><div dir=3D"auto"><br></div><div dir=3D"auto">Ashutosh, s=
hould we document this or it is a well known fact and not needed? Asking in=
 the context of Graphs, not views.</div><div dir=3D"auto"><br></div><div di=
r=3D"auto"><br></div><div dir=3D"auto">Thanks,</div><div dir=3D"auto">Satya=
</div></div></div>

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