> > If log record was not really flushed on disk in 3. but 
> > on-disk image of index block was updated in 4. and system
> > crashed after this then after restart recovery you'll have
> > unlawful index tuple pointing to where? Who knows!
> > No guarantee that corresponding heap tuple was flushed on
> > disk.
> 
> This example doesn't seem very convincing.  Wouldn't the XLOG entry
> describing creation of the heap tuple appear in the log before the one
> for the index tuple?  Or are you assuming that both these XLOG entries
> are lost due to disk drive malfeasance?

Yes, that was assumed.
When UNDO will be implemented and uncomitted tuples will be removed by
rollback part of after crash recovery we'll get corrupted database without
that assumption.

Vadim

Fri, 12 Jan 2001 16:55:08 -0800
"Mikheev, Vadim" <vmikheev@SECTORBASE.COM>
RE: CRCs 