Re: how to add more than 1600 columns in a table?

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От Alvaro Herrera
Тема Re: how to add more than 1600 columns in a table?
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Msg-id 20190424225519.GA8439@alvherre.pgsql
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Ответ на Re: how to add more than 1600 columns in a table?  (pabloa98 <pabloa98@gmail.com>)
Ответы Re: how to add more than 1600 columns in a table?  (Alvaro Herrera <alvherre@2ndquadrant.com>)
Re: how to add more than 1600 columns in a table?  (Ron <ronljohnsonjr@gmail.com>)
Re: how to add more than 1600 columns in a table?  (Gavin Flower <GavinFlower@archidevsys.co.nz>)
Список pgsql-general
On 2019-Apr-24, pabloa98 wrote:

> Regarding to (2), We are good by adding a patch and recompile a patched
> version for our server databases.
> 
> But we are open on helping to add thousands of columns support as a
> compile-time parameter if there are other people interested.

It's hard to say what you're doing wrong when we don't know
what are you actually doing.

I think raising the limit requires changing ItemIdData, t_hoff, and a
few members of PageHeaderData at the very least.  Reading the three
header files involved carefully would probably point out areas I've
forgotten to mention.  I think if you enlarge t_hoff and lp_off/lp_len
to 16 bits, you can use 64kB blocks, which might be useful too.

Note that with pg12 you could have your own table AM that supported
wider ItemIds as a (small?) change on heapam, rather than supplant it
for all tables.  That way you would only pay the (probably considerable)
cost of the wider line pointers on all tables ...

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services



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