Re: [HACKERS] Does having a NULL column automatically exclude thetable from the tupleDesc cache?

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От Jim Nasby
Тема Re: [HACKERS] Does having a NULL column automatically exclude thetable from the tupleDesc cache?
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Msg-id a8c86d85-0117-ce74-5348-5ed6d17603b6@BlueTreble.com
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Ответ на Re: [HACKERS] Does having a NULL column automatically exclude thetable from the tupleDesc cache?  (Ryan Murphy <ryanfmurphy@gmail.com>)
Ответы Re: [HACKERS] Does having a NULL column automatically exclude thetable from the tupleDesc cache?  (Robert Haas <robertmhaas@gmail.com>)
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On 2/15/17 1:37 PM, Ryan Murphy wrote:
>
>     attcacheoff can only be set positive for fields preceding any varlena
>     (typlen<0, but including the first such) or nullable values.  I don't
>     know how much faster it is with the cache; you can measure it if your
>     curiosity is strong enough -- just set the first column to nullable.
>
>
> Thanks!  Maybe I'll do some benchmarks.

You'll probably want to do those at a C level, bypassing the executor. I 
would guess that executor overhead will completely swamp the effect of 
the cache in most cases.
-- 
Jim Nasby, Data Architect, Blue Treble Consulting, Austin TX
Experts in Analytics, Data Architecture and PostgreSQL
Data in Trouble? Get it in Treble! http://BlueTreble.com
855-TREBLE2 (855-873-2532)



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