What is Revdb_commit() for anyway?
janschenkel at yahoo.com
Tue Jan 13 15:15:19 CST 2009
--- Bob Sneidar <bobs at twft.com> wrote:
> Ohhh, so let me see if I get it. I issue a series of
> statements, but the data is not actually in the
> database yet so
> another user querying the database for those records
> would see what
> the data "used to be" until I issue a a
> I can use that to my advantage I suppose.
> Bob Sneidar
Of course the database has to support transactions
(not all databases do - for MySQL you have to use the
InnoDB engine rather than the MyISAM engine, for
instance) but it is a very powerful feature.
Suppose you're writing all the database changes
required for selling an article: you have to add the
invoice detail line, the invoice header record, the
article history, the inventory, etc.
It is vital that either all these changes are applied,
or none of them are - otherwise you have logical
errors in your database. With transactions, it's as
simple as committing at the end of the entire update
procedure. If your app crashes in the middle, all the
steps will be rolled back until the previous commit -
so your data will be okay.
Naturally, this is best combined with an
<http://en.wikipedia.org/wiki/ACID> to make sure that
your database will survive a power cut. SQLite and
PostgreSQL are free ACID-compliant databases with
transactions and Rev ships with drivers for them.
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