> 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
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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