Re: AW: AW: Re: Backup and Recovery

Zeugswetter Andreas SB <ZeugswetterA@wien.spardat.at> writes:
>> Wouldn't it be the same as the case where we *do* have UNDO?  How is a
>> removed tuple different from a tuple that was never there?

> HiHi, the problem is a subtile one. What if a previously aborted txn 
> produced a btree page split, that would otherwise not have happened ?

Good point.  We'd have to recognize btree splits (and possibly some
other operations) as things that must be done anyway, even if their
originating transaction is aborted.

There already is a mechanism for doing that: xlog entries can be written
without any transaction identifier (see XLOG_NO_TRAN).  Seems to me that
btree split XLOG records should be getting written that way now --- Vadim,
don't you agree?
        regards, tom lane