Re: Search from newer tuples first, vs older tuples first?

Tom Lane wrote:
> Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> > It is not that hard to implement, just messy. When the index returns a
> > heap row and the heap row is viewed for visibility, if _no_one_ can see
> > the row, the index can be marked as expired. It could be a single bit
> > in the index tuple, and doesn't need to be flushed to disk, though the
> > index page has to be marked as dirty. However, we are going to need to
> > flush a pre-change image to WAL so it may as well be handled as a normal
> > index page change.
>
> This did actually get done while you were on vacation. It does *not*
> need a WAL entry, on the same principle that setting XMIN_COMMITTED,
> XMAX_ABORTED, etc hint bits do not need WAL entries --- namely the
> bits can always get set again if they are lost in a crash.

Oh, thanks. That is great news. I am having trouble determining when a
thread ends so please be patient with me.

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