[Dbix-class] Optimistic locking

[Steven Mackenzie]

I admit that I skimmed through the start of the thread, and had assumed
by "hash" you meant a hash object containing the original {
columns=>values }; I also assumed that DBIx::Class kept that hash of
original values in memory, however I've just checked
DBIx::Class::PK::discard_changes, and seen that it doesn't.

However ...

Dan Horne wrote:

>Well if I can't add an extra column (either hash or version), wouldn't I
>need to read the whole row and recompute the original hash with every update
>or delete to every single row? Sounds expensive to me, which is why I moved
>away from using hashes as I originally proposed.
>  
>
An option would be to keep original column values in memory (copy on
change), and then on ->update(), add
col1=orig_val1 AND col2 = orig_val2 AND ...
to the SQL update where clause.

Can your module do that?

>The alternative version column approach is a common optimistic locking
>design pattern and is supported by Hibernate and Toplink, for instance. I
>guess it comes down to whichever ORM you wish to cite...
>
>  
>
True -- I don't have wide experience with such things, but find the
ADO.Net approach nicely straightforward, and you don't even need to know
that it's doing it.