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Thread: Staus of Primary/Foreign key?

Staus of Primary/Foreign key?

From
"Stan Brown"
Date:
    I have implemented referential integrity in older Postgres projects
    using functions. I am preparing to do a new project, aand was wondering
    what the status of Primary/Foreign key implementation was?

    I am starting with 6.4.2,

    Thanks.

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Westvaco
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    originally coded for a 4-bit microprocessor, written by a 2-bit
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(c) 1999 Stan Brown.  Redistribution via the Microsoft Network is prohibited.

Re: [SQL] Staus of Primary/Foreign key?

From
jwieck@debis.com (Jan Wieck)
Date:
>
>    I have implemented referential integrity in older Postgres projects
>    using functions. I am preparing to do a new project, aand was wondering
>    what the status of Primary/Foreign key implementation was?
>
>    I am starting with 6.4.2,

    I'm  planning  to implement most of the constraints currently
    missing (foreign key, cascaded deletes) over rules  -  or  at
    least making the rule system capable of supporting it.

    But  it  will  not  be  in  v6.5. The reason for that is that
    constraints need a special feature, the rule system currently
    cannot  support.  It  is  required  that  rule actions can be
    deferred until transaction commit time.   At  that  time  (or
    when  they  should  get  run  anyway), they need very special
    visibility of heap tuples on a per range table base. One  and
    the  same  table  might  have  to  be  scanned with different
    snapshot's in one query.

    That all will take a while.


Jan

--

#======================================================================#
# It's easier to get forgiveness for being wrong than for being right. #
# Let's break this rule - forgive me.                                  #
#======================================== jwieck@debis.com (Jan Wieck) #

Re: [SQL] Staus of Primary/Foreign key?

From
Bruce Momjian
Date:
> >
> >    I have implemented referential integrity in older Postgres projects
> >    using functions. I am preparing to do a new project, aand was wondering
> >    what the status of Primary/Foreign key implementation was?
> >
> >    I am starting with 6.4.2,
>
>     I'm  planning  to implement most of the constraints currently
>     missing (foreign key, cascaded deletes) over rules  -  or  at
>     least making the rule system capable of supporting it.
>
>     But  it  will  not  be  in  v6.5. The reason for that is that
>     constraints need a special feature, the rule system currently
>     cannot  support.  It  is  required  that  rule actions can be
>     deferred until transaction commit time.   At  that  time  (or
>     when  they  should  get  run  anyway), they need very special
>     visibility of heap tuples on a per range table base. One  and
>     the  same  table  might  have  to  be  scanned with different
>     snapshot's in one query.
>
>     That all will take a while.

I am glad to hear Jan say this.  I hoped he had not given up on the idea
of doing foreign keys.  This is a major feature people are requesting.

--
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