[Opensim-dev] Release 0.7 RC1 Test Feedback

[Alex Ra]

DC> As far as I understand it, the new driver was added because it
DC> supports stored procedures [better?]; stored procedures will allow
DC> us to speed up some things. But 0.7 still doesn't have any stored
DC> procedures, so the new capabilities are mute.


Hello Diva,

It was me who put the updated MySql driver into the project, so I'm
the one to kick for the mess.

 The reasons were:

(a) Yes, the ability to *define* multi-statement stored procs. MySQL has
a rather hairy way to switch DELIMITER while defining an SP, so
defining anything with a ';' inside was either impossible or very tricky
with the previous driver.

You are also correct that stored procs are NOT used currently, however
they can be used to provide "fast" tracking of asset access times,
which, as I understand, is required for cleaning up unused assets and
preventing the database from growing infinitely. The relevant code is
ready, tested and described by me somewhere on Mantis, with a link to
github, but I don't think anybody has bothered to review / merge it
(yet).

The last time I looked, the access tracking functionality was
commented out in the asset store code, because sending an UPDATE after
each asset fetch just kills the performance (like 10 times slower).
The solution based on stored procs has a performance penalty of about
10-15%.

I can re-post the link to Mantis where this approach is described, if
anybody is interested.

(b) the less important reason is just to keep up with the most recent
versions of the driver.

Updating the driver also involved some changes in the stores to
correctly convert between values returned/accepted by the driver and
UUIDs in the code. The reason is that the new driver implicitly
converts CHAR(36), returning it as Guid (rather than a string). With
the "Old Guids" config var, the driver would instead convert
BINARY(16) to Guid.

With the new driver and the corresponding code changes in place, the
"Old Guids" config var should NOT be used.


Best regards,

Alex