[redland-dev] Concurrent updates with MySQL storage engine

[Dave Beckett]

Jan Algermissen wrote:
> Hi,
> 
> AFAIK, transactionality has not yet been added to Redland and as the
> MySQL storage uses ISAM (as opposed to InnoDB) tables, so I cannot
> really add it myself by simply getting hold of the connection handle. At
> least not without loosing the ability to update redland with new releases.

but we could add storage parameters to let you switch table type (small
change) or add an API call to get the connection handle (another small change)

> Does anyone know, how/if massive update concurrency[1] affects creation
> of single statements? I am not concerned so much with rollbacks, only
> with added statements being correct. IOW, my business logic would not
> suffer from concurrency but I need to be sure the individual statements
> do not get screwed up.
>
> [1] Could be that aprox. 200 clients hit the DB at the same time and try
> to remove all statements of a context and then insert several hundred
> new statements in that context . No two clients would use the same context.

I think massive concurrency would probably be problematic, you are really
wanting transactions so that overlapping updates - which require multiple
SQL commands - will work correctly in all cases.  Adding transactions would
be a medium sized project.  The tracking bug for this is
  http://bugs.librdf.org/mantis/view.php?id=38

Dave