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

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От Ryan Murphy
Тема Re: [HACKERS] Does having a NULL column automatically exclude thetable from the tupleDesc cache?
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Msg-id CAHeEsBcx-v+JmsWuXMnCdnVduhuavtYiHpLhj=Kwab0MCm65Hw@mail.gmail.com
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Ответ на Re: [HACKERS] Does having a NULL column automatically exclude the table from the tupleDesc cache?  (Tom Lane <tgl@sss.pgh.pa.us>)
Ответы Re: [HACKERS] Does having a NULL column automatically exclude thetable from the tupleDesc cache?  (Alvaro Herrera <alvherre@2ndquadrant.com>)
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No, that tests whether the particular tuple contains any null fields, not
whether the whole table is declared NOT NULL.

                        regards, tom lane

Ok, thanks, that makes sense.

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.  Thanks again!

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