Re: [HACKERS] trouble with rules

I wrote:
>
> Tom Lane wrote:
>
> > Calm down Jan ;-).  I think what happened here is a slightly careless
> > merge of the 6.3 - based INTERSECT/EXPECT code into the current code.
> > Not a deliberate removal of a feature, just a foulup.
>
>     Was  my fault too. I should have added this new syntax to the
>     regression (as I did now). That way I would have  noticed  as
>     early as can that something disappeared.
>
> >
> > This does suggest that we need to be more careful when applying patches
> > developed against old system versions.
>
>     This does suggest that we need to pay more attention that all
>     the nifty things we do are added to the regression suite.
>
>     Saying this I've just checked and the examples  I've  written
>     in  the  rule  system section of the programmers manual cause
>     the backend to dump core.
>
>     Isn't if funny? All I'm telling could be used against me. :-)

    No, it isn't fun any more and I'm getting angry now >:-(

    I've  checked  it  and  it turns out, that due to the changes
    that came in with INTERSECT/EXPECT  many  expressions  aren't
    any  longer  copied when they are added from one parsetree to
    another. Thus, multiple parsetrees  reference  the  same  Var
    nodes  and  if  multiple  rules  get  applied during the rule
    system recursion (rewritten trees get rewritten again), later
    rules  mangle up the ones referenced in trees the rule system
    is already done with.

    I've spent night's to fix  this  all  for  v6.4.  Added  many
    copyObject()'s  around things that MUST be copied. Now I find
    them commented out, because it was easier to apply v6.3 based
    development onto the v6.5 sources.

    I'll  now revert things to do the copyObject() again where it
    has to be done and will add the examples from the programmers
    manual to the regression tests.

    Surely  this will break the INTERSECT/EXPECT code, because it
    depends on nodes beeing  at  specific  memory  locations  for
    comparisions.  But this is impossible due to the requirements
    of the rule system.

    Sorry for that.


Jan

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