Re: Australian timezone configure option

> Bruce Momjian <pgman@candle.pha.pa.us> writes:
> > OK, this patch makes Australian_timezones a GUC option.  It can be set
> > anytime in psql.  The code uses a static variable to check if the GUC
> > setting has changed and adjust the C struct accordingly.
> 
> This is a horrid approach.  What if you get an error partway through
> scribbling on the static table?  Then you've got inconsistent data.

I have set the variable to -1 on entry so it will reload on failure,
though it is only doing C lookups on a static table so it is hard to see
how it would fail.

> Nor do I much care for having to execute a check subroutine before any
> use of the lookup table (quite aside from speed, are you sure it's being
> called before *every* use of the table?  how will you make sure that
> people remember to call it when they add new routines that use the
> table?).  If you're going to scribble on the table, ISTM you should
> drive that off an assignment-hook callback from the GUC stuff.

But we don't have such hooks so I did it with as little code as
possible.  The table itself is 'static' so it is only called in this
function.  (The old patch had the static removed because I thought I was
going to have to do this stuff in the guc files but now it is all in the
same file.)

> Besides which, you forgot to mark the control variable static...
> so it doesn't actually reflect the state of the table.

Fixed.  I had that in an ealier version but forgot to add it when I
moved it out to a separate function.

> It would be a lot cleaner to extend the lookup table structure so that
> you don't need to change the table contents to track the Aussie-rules
> setting.

Yes, when we do that we can remove the call and call it instead from the
GUC setting.

Here is a new version of the patch.  I found I didn't need to clear the
date cache.

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