v10beta pg_catalog diagrams

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v10beta pg_catalog diagrams

Neil Anderson-2
Hi,

I'm cross posting from general. I did some work to diagram the
relationships in pg_catalog for v10. I would like to add it to the
developer FAQ here
https://wiki.postgresql.org/wiki/Developer_FAQ#Is_there_a_diagram_of_the_system_catalogs_available.3F 
but I thought I should check if people thought it appropriate and useful
before I do?

https://www.postgrescompare.com/2017/06/11/pg_catalog_constraints.html

Thanks,
Neil

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Re: v10beta pg_catalog diagrams

Peter Eisentraut-6
On 6/12/17 11:28, Neil Anderson wrote:
> I'm cross posting from general. I did some work to diagram the
> relationships in pg_catalog for v10. I would like to add it to the
> developer FAQ here
> https://wiki.postgresql.org/wiki/Developer_FAQ#Is_there_a_diagram_of_the_system_catalogs_available.3F 
> but I thought I should check if people thought it appropriate and useful
> before I do?
>
> https://www.postgrescompare.com/2017/06/11/pg_catalog_constraints.html

Go for it.

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Re: v10beta pg_catalog diagrams

Bruce Momjian
On Mon, Jun 12, 2017 at 04:07:35PM -0400, Peter Eisentraut wrote:

> On 6/12/17 11:28, Neil Anderson wrote:
> > I'm cross posting from general. I did some work to diagram the
> > relationships in pg_catalog for v10. I would like to add it to the
> > developer FAQ here
> > https://wiki.postgresql.org/wiki/Developer_FAQ#Is_there_a_diagram_of_the_system_catalogs_available.3F 
> > but I thought I should check if people thought it appropriate and useful
> > before I do?
> >
> > https://www.postgrescompare.com/2017/06/11/pg_catalog_constraints.html
>
> Go for it.

Yeah, great.  We have been talking about adding diagrams to our
official docs but needed an updated toolchain, which I think we now
have, so there is a lot of opportunity for growth here.

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Re: v10beta pg_catalog diagrams

Neil Anderson-2
On 2017-06-13 1:22 PM, Bruce Momjian wrote:

> On Mon, Jun 12, 2017 at 04:07:35PM -0400, Peter Eisentraut wrote:
>> On 6/12/17 11:28, Neil Anderson wrote:
>>> I'm cross posting from general. I did some work to diagram the
>>> relationships in pg_catalog for v10. I would like to add it to the
>>> developer FAQ here
>>> https://wiki.postgresql.org/wiki/Developer_FAQ#Is_there_a_diagram_of_the_system_catalogs_available.3F
>>> but I thought I should check if people thought it appropriate and useful
>>> before I do?
>>>
>>> https://www.postgrescompare.com/2017/06/11/pg_catalog_constraints.html
>>
>> Go for it.
>
> Yeah, great.  We have been talking about adding diagrams to our
> official docs but needed an updated toolchain, which I think we now
> have, so there is a lot of opportunity for growth here.
>

Wonderful. I've added it.

There were a few relationships that I couldn't capture. Like where in
pg_extension extconfig is an array of oids that refer to pg_class or
where pg_depends could refer to basically any other system catalog, but
it's mostly there and has all 62 tables from pg_catalog.

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Re: v10beta pg_catalog diagrams

Robert Haas
On Tue, Jun 13, 2017 at 3:14 PM, Neil Anderson <[hidden email]> wrote:
> There were a few relationships that I couldn't capture. Like where in
> pg_extension extconfig is an array of oids that refer to pg_class or where
> pg_depends could refer to basically any other system catalog, but it's
> mostly there and has all 62 tables from pg_catalog.

At the risk of tooting my own horn, if you happen to have a damaged
database where you think that the pseudo-foreign-key relationships
don't actually hold, you can run
https://github.com/EnterpriseDB/pg_catcheck to find the problems.  It
checks things like extconfig and pg_depend links, too.

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Re: v10beta pg_catalog diagrams

Andres Freund
In reply to this post by Neil Anderson-2
Hi,

On 2017-06-12 11:28:39 -0400, Neil Anderson wrote:
> I'm cross posting from general. I did some work to diagram the relationships
> in pg_catalog for v10. I would like to add it to the developer FAQ here https://wiki.postgresql.org/wiki/Developer_FAQ#Is_there_a_diagram_of_the_system_catalogs_available.3F
> but I thought I should check if people thought it appropriate and useful
> before I do?
>
> https://www.postgrescompare.com/2017/06/11/pg_catalog_constraints.html

I wondered before if we shouldn't introduce "information only"
unenforced foreign key constraints for the catalogs.  We kind of
manually do that via oidjoins, it'd be nicer if we'd a function
rechecking fkeys, and the fkeys were in the catalog...

- Andres


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Re: v10beta pg_catalog diagrams

Peter Eisentraut-6
On 6/13/17 17:08, Andres Freund wrote:
> I wondered before if we shouldn't introduce "information only"
> unenforced foreign key constraints for the catalogs.  We kind of
> manually do that via oidjoins, it'd be nicer if we'd a function
> rechecking fkeys, and the fkeys were in the catalog...

I don't see why we couldn't just add a full complement of primary and
foreign key constraints (and unique constraints and perhaps some check
constraints).  The argument is that they wouldn't normally do anything,
but they would help with documentation and browsing tools, and they
wouldn't hurt anything.

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Re: v10beta pg_catalog diagrams

Pavel Stehule


2017-06-14 5:53 GMT+02:00 Peter Eisentraut <[hidden email]>:
On 6/13/17 17:08, Andres Freund wrote:
> I wondered before if we shouldn't introduce "information only"
> unenforced foreign key constraints for the catalogs.  We kind of
> manually do that via oidjoins, it'd be nicer if we'd a function
> rechecking fkeys, and the fkeys were in the catalog...

I don't see why we couldn't just add a full complement of primary and
foreign key constraints (and unique constraints and perhaps some check
constraints).  The argument is that they wouldn't normally do anything,
but they would help with documentation and browsing tools, and they
wouldn't hurt anything.


These constraints can slowdown creating/dropping database objects - mainly temp tables.

Regards

Pavel
 
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Re: v10beta pg_catalog diagrams

Andres Freund
On 2017-06-14 06:05:24 +0200, Pavel Stehule wrote:

> 2017-06-14 5:53 GMT+02:00 Peter Eisentraut <[hidden email]
> >:
>
> > On 6/13/17 17:08, Andres Freund wrote:
> > > I wondered before if we shouldn't introduce "information only"
> > > unenforced foreign key constraints for the catalogs.  We kind of
> > > manually do that via oidjoins, it'd be nicer if we'd a function
> > > rechecking fkeys, and the fkeys were in the catalog...
> >
> > I don't see why we couldn't just add a full complement of primary and
> > foreign key constraints (and unique constraints and perhaps some check
> > constraints).  The argument is that they wouldn't normally do anything,
> > but they would help with documentation and browsing tools, and they
> > wouldn't hurt anything.

Well, unique constraints are a bit more complicated because they rely on
an index, and we wouldn't e.g. maintain indexes with WHERE clauses or
other expressions correctly.  I'd be a bit wary of declaring such
indexes as actually being fully valid, because we have planner logic
that does planning based on various constraints now, it'd certainly be
annoying if some "re-check constraint" type queries would actually have
their joins optimized away or such...

> These constraints can slowdown creating/dropping database objects - mainly
> temp tables.

How so?

- Andres


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Re: v10beta pg_catalog diagrams

Pavel Stehule


2017-06-14 19:49 GMT+02:00 Andres Freund <[hidden email]>:
On 2017-06-14 06:05:24 +0200, Pavel Stehule wrote:
> 2017-06-14 5:53 GMT+02:00 Peter Eisentraut <[hidden email]
> >:
>
> > On 6/13/17 17:08, Andres Freund wrote:
> > > I wondered before if we shouldn't introduce "information only"
> > > unenforced foreign key constraints for the catalogs.  We kind of
> > > manually do that via oidjoins, it'd be nicer if we'd a function
> > > rechecking fkeys, and the fkeys were in the catalog...
> >
> > I don't see why we couldn't just add a full complement of primary and
> > foreign key constraints (and unique constraints and perhaps some check
> > constraints).  The argument is that they wouldn't normally do anything,
> > but they would help with documentation and browsing tools, and they
> > wouldn't hurt anything.

Well, unique constraints are a bit more complicated because they rely on
an index, and we wouldn't e.g. maintain indexes with WHERE clauses or
other expressions correctly.  I'd be a bit wary of declaring such
indexes as actually being fully valid, because we have planner logic
that does planning based on various constraints now, it'd certainly be
annoying if some "re-check constraint" type queries would actually have
their joins optimized away or such...

> These constraints can slowdown creating/dropping database objects - mainly
> temp tables.

How so?

execution RI triggers

Regards

Pavel
 

- Andres

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Re: v10beta pg_catalog diagrams

Andres Freund


On June 14, 2017 7:53:05 PM PDT, Pavel Stehule <[hidden email]> wrote:

>2017-06-14 19:49 GMT+02:00 Andres Freund <[hidden email]>:
>
>> On 2017-06-14 06:05:24 +0200, Pavel Stehule wrote:
>> > 2017-06-14 5:53 GMT+02:00 Peter Eisentraut <
>> [hidden email]
>> > >:
>> >
>> > > On 6/13/17 17:08, Andres Freund wrote:
>> > > > I wondered before if we shouldn't introduce "information only"
>> > > > unenforced foreign key constraints for the catalogs.  We kind
>of
>> > > > manually do that via oidjoins, it'd be nicer if we'd a function
>> > > > rechecking fkeys, and the fkeys were in the catalog...
>> > >
>> > > I don't see why we couldn't just add a full complement of primary
>and
>> > > foreign key constraints (and unique constraints and perhaps some
>check
>> > > constraints).  The argument is that they wouldn't normally do
>anything,
>> > > but they would help with documentation and browsing tools, and
>they
>> > > wouldn't hurt anything.
>>
>> Well, unique constraints are a bit more complicated because they rely
>on
>> an index, and we wouldn't e.g. maintain indexes with WHERE clauses or
>> other expressions correctly.  I'd be a bit wary of declaring such
>> indexes as actually being fully valid, because we have planner logic
>> that does planning based on various constraints now, it'd certainly
>be
>> annoying if some "re-check constraint" type queries would actually
>have
>> their joins optimized away or such...
>>
>> > These constraints can slowdown creating/dropping database objects -
>> mainly
>> > temp tables.
>>
>> How so?
>>
>
>execution RI triggers

Those would obviously bit be fired, given Peter's description?

Andres
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Re: v10beta pg_catalog diagrams

Pavel Stehule


2017-06-15 5:02 GMT+02:00 Andres Freund <[hidden email]>:


On June 14, 2017 7:53:05 PM PDT, Pavel Stehule <[hidden email]> wrote:
>2017-06-14 19:49 GMT+02:00 Andres Freund <[hidden email]>:
>
>> On 2017-06-14 06:05:24 +0200, Pavel Stehule wrote:
>> > 2017-06-14 5:53 GMT+02:00 Peter Eisentraut <
>> [hidden email]
>> > >:
>> >
>> > > On 6/13/17 17:08, Andres Freund wrote:
>> > > > I wondered before if we shouldn't introduce "information only"
>> > > > unenforced foreign key constraints for the catalogs.  We kind
>of
>> > > > manually do that via oidjoins, it'd be nicer if we'd a function
>> > > > rechecking fkeys, and the fkeys were in the catalog...
>> > >
>> > > I don't see why we couldn't just add a full complement of primary
>and
>> > > foreign key constraints (and unique constraints and perhaps some
>check
>> > > constraints).  The argument is that they wouldn't normally do
>anything,
>> > > but they would help with documentation and browsing tools, and
>they
>> > > wouldn't hurt anything.
>>
>> Well, unique constraints are a bit more complicated because they rely
>on
>> an index, and we wouldn't e.g. maintain indexes with WHERE clauses or
>> other expressions correctly.  I'd be a bit wary of declaring such
>> indexes as actually being fully valid, because we have planner logic
>> that does planning based on various constraints now, it'd certainly
>be
>> annoying if some "re-check constraint" type queries would actually
>have
>> their joins optimized away or such...
>>
>> > These constraints can slowdown creating/dropping database objects -
>> mainly
>> > temp tables.
>>
>> How so?
>>
>
>execution RI triggers

Those would obviously bit be fired, given Peter's description?

ok
 

Andres
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Re: v10beta pg_catalog diagrams

Andres Freund
In reply to this post by Andres Freund
On 2017-06-14 20:02:27 -0700, Andres Freund wrote:

> On June 14, 2017 7:53:05 PM PDT, Pavel Stehule <[hidden email]> wrote:
> >2017-06-14 19:49 GMT+02:00 Andres Freund <[hidden email]>:
> >> > These constraints can slowdown creating/dropping database objects -
> >> mainly
> >> > temp tables.
> >>
> >> How so?
> >>
> >
> >execution RI triggers
>
> Those would obviously bit be fired, given Peter's description?

Gah, stupid autocorrect.  *not* be fired.  Unless you mean something
else than the speed of catalog manipulations themselves, in which case I
still don't understand.

- Andres


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Re: v10beta pg_catalog diagrams

Pavel Stehule


2017-06-15 5:06 GMT+02:00 Andres Freund <[hidden email]>:
On 2017-06-14 20:02:27 -0700, Andres Freund wrote:
> On June 14, 2017 7:53:05 PM PDT, Pavel Stehule <[hidden email]> wrote:
> >2017-06-14 19:49 GMT+02:00 Andres Freund <[hidden email]>:
> >> > These constraints can slowdown creating/dropping database objects -
> >> mainly
> >> > temp tables.
> >>
> >> How so?
> >>
> >
> >execution RI triggers
>
> Those would obviously bit be fired, given Peter's description?

Gah, stupid autocorrect.  *not* be fired.  Unless you mean something
else than the speed of catalog manipulations themselves, in which case I
still don't understand.

No, just this. I missed it.

Regards

Pavel
 

- Andres