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

Ryan Murphy wrote:

> My question kind of remains though - does that mean that having any nulls
> in the tuple loses the ability to use the tupleDesc cache? and how much of
> a performance impact is this?  I'm sure there's a good reason why you can't
> really use the cache if you have a null column, just was curious of the
> implications.

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.

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
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