| From: | "Zeugswetter Andreas SB SD" <ZeugswetterA(at)spardat(dot)at> |
|---|---|
| To: | "Bruce Momjian" <pgman(at)candle(dot)pha(dot)pa(dot)us>, "Mikheev, Vadim" <vmikheev(at)SECTORBASE(dot)COM> |
| Cc: | "PostgreSQL-development" <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Savepoints |
| Date: | 2002-01-25 21:03:53 |
| Message-ID: | 46C15C39FEB2C44BA555E356FBCD6FA41EB4C4@m0114.s-mxs.net |
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| Lists: | pgsql-hackers |
> Now, with MVCC, the backend has to read through the redo segment to get
You mean rollback segment, but ...
> the original data value for that row.
Will only need to be looked up if the row is currently beeing modified by
a not yet comitted txn (at least in the default read committed mode)
>
> Now, while rollback segments do help with cleaning out old UPDATE rows,
> how does it improve DELETE performance? Seems it would just mark it as
> expired like we do now.
delete would probably be:
1. mark original deleted and write whole row to RS
I don't think you would like to mix looking up deleted rows in heap
but updated rows in RS
Andreas
PS: not that I like overwrite with MVCC now
If you think of VACUUM as garbage collection PG is highly trendy with
the non-overwriting smgr.
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