Re: [HACKERS] Performance problem partially identified

> > This could only be from the call to SetBufferCommitInfoNeedsSave in
> > the HeapTupleSatisfies macro.  If I'm reading the code correctly,
> > that means that HeapTupleSatisfiesSnapshot() always changes the
>                                                ^^^^^^^^^^^^^^
> > t_infomask field of the tuple.
> 
> Not always but only if HEAP_XMIN_COMMITTED/HEAP_XMAX_COMMITTED
> are not setted. Run vacuum before update and SetBufferCommitInfoNeedSave
> will not be called. This func is just to avoid pg_log lookup
> without vacuum.
> 

Yes, we store the transaction status on first in the tuple so we don't
have to look it up.

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