[lug] mysqldump versus snapshot versus..

[dio2002 at indra.com]

> Most real databases write updates to the transaction log, and once
> they're written to the transaction log, they then write them to the
> underlying tables.
>
> A backup process usually just suspends the writer process from doing
> this until the backup completes.
>
> Of course, where this gets icky is when you have someone reading. The
> engine has to check the transaction log to see if the rows it's
> returning are affected by an update, and if so, return those.

that simple tidbit explains in layman's terms how "real" dbs get around
the lock tables problem.  thanks for sharing it.  it clarifies the matter
for me a whole lot.