Re: Transaction Performance Question

On Wed, 29 Oct 2003, Rick Gigger wrote:

> In the following situation:
>
> You do a large transaction where lots of rows are update
> All of your tables/indexes cached in memory
>
> When are the updated rows written out to disk?  When they are updated inside
> the transaction, or when the transaction is completed?

The data is written out but not made real, so to speak, during each
update.  I.e. the updates individually add all these rows.  At the end of
the transaction, if we rollback, all the tuples that were written out are
simply not committed, and therefore the last version of that record
remains the last one in the chain.

If the transaction is committed then each tuple becomes the last in its
chain (could it be second to last because of other transactions?  I'm not
sure.)