Tom Lane <tgl@sss.pgh.pa.us> wrote:
> > Why do index access methods use LP_DELETE?
>
> My recollection is that I deliberately used LP_DELETE for the
> known-dead-tuple marker so that there couldn't be any confusion with
> the use of LP_USED. AFAIR, LP_USED isn't actually used in indexes,
> so we could do it differently if there were another possible use for
> the flag bit ... have you got one in mind?
Thanks. I understood there is little difference
between non-LP_USED and LP_DELETE for indexes.
I'm thinking to use LP_DELETE for relation tuples for incremental vacuum,
which is discussed in http://archives.postgresql.org/pgsql-hackers/2005-03/msg00518.php
I'll try to mark tuples with LP_DELETE on visibility checking and
recycle the pages by bgwriter.
...However it is still a stage of an idea.
---
ITAGAKI Takahiro
NTT Cyber Space Laboratories