PostgreSQL Discussion - postgres optimizer

Author

postgres optimizer

Hossein S. Attar

2005-08-26, 11:23 am

Hi:
I am working on postgres optimizer code to add some statistics
collection features for an academic project. At some point in my work, I
need to be able to tell if a join is a foreign key join or not. Also in
case of a foreign key join, I need to identify which input to the join
operator has the primary key attribute and which one has teh foreign
key. In other words, when we are making a JoinPath struct, I need to
identify if the join between the inner and outer RelOptInfo structs is a
foreign key join and if so, which RelOptInfo has the primary key. Does
anyone know the best way to do this? Should I go to "joinrestrictinfo"
field and go over all expressions? Is there any easier way?

Regards,
HSA

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Tom Lane

2005-08-26, 11:23 am

"Hossein S. Attar" <mhsheikh@softbase.math.uwaterloo.ca> writes:
> I am working on postgres optimizer code to add some statistics
> collection features for an academic project. At some point in my work, I
> need to be able to tell if a join is a foreign key join or not. Also in
> case of a foreign key join, I need to identify which input to the join
> operator has the primary key attribute and which one has teh foreign
> key. In other words, when we are making a JoinPath struct, I need to
> identify if the join between the inner and outer RelOptInfo structs is a
> foreign key join and if so, which RelOptInfo has the primary key. Does
> anyone know the best way to do this? Should I go to "joinrestrictinfo"
> field and go over all expressions? Is there any easier way?

The planner doesn't think there is any such thing as a "foreign key
join". Perhaps you should modify the foreign key triggers (in
ri_triggers.c) to collect the information you need.

regards, tom lane

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Joshua D. Drake

2005-08-26, 1:23 pm

Tom Lane wrote:
> "Hossein S. Attar" <mhsheikh@softbase.math.uwaterloo.ca> writes:
>

I would be interested in knowing "why" you want to do such a thing? What
is it you expect to gain?

Sincerely,

Joshua D. Drake
[color=darkred]
>
>
> The planner doesn't think there is any such thing as a "foreign key
> join". Perhaps you should modify the foreign key triggers (in
> ri_triggers.c) to collect the information you need.
>
> regards, tom lane
>
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>
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Hossein S. Attar

2005-08-30, 11:25 am

Like I said it's a research project. There is a feature that I'm trying
to add to optimizer, but this feature should only be used when a join is
a foreign key join.

Hossein

Joshua D. Drake wrote:

>
> I would be interested in knowing "why" you want to do such a thing? What
> is it you expect to gain?
>
> Sincerely,
>
> Joshua D. Drake
>
>
>
>

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