Re: More then 1600 columns?

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От Tom Lane
Тема Re: More then 1600 columns?
Дата
Msg-id 8914.1289620175@sss.pgh.pa.us
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Ответ на Re: More then 1600 columns?  ("Clark C. Evans" <cce@clarkevans.com>)
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"Clark C. Evans" <cce@clarkevans.com> writes:
> What would be most helpful though is if the answer to
> this question stop being an attack on the business
> requirement analysis, database design skills, and/or
> sanity of the requester.  It's a limitation of
> PostgreSQL's implementation; a deliberate performance
> trade-off that is infeasible to change.

Just for the record: I don't think its *infeasible* to change it.
What I'm saying is that it would be a bad tradeoff for the vast
majority of users.

I could imagine accepting a patch that provides a compile-time option
to change the limit.  The core of it would be something like

+    #ifdef SUPPORT_RIDICULOUSLY_MANY_COLUMNS
+        uint16    t_hoff;        /* sizeof header incl. bitmap, padding */
+    #else
        uint8    t_hoff;        /* sizeof header incl. bitmap, padding */
+    #endif

plus whatever other fallout ensues elsewhere.  But somebody would have
to step up to develop and test such a patch, and keep on testing it to
ensure no bit-rot sets in, because it seems very unlikely that any
mainstream distributions would ever choose to enable the option.
I don't think any of the core developers have any interest in hacking
on this; we have bigger fish to fry.  So it'd be a matter of someone
scratching their own itch.

            regards, tom lane

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