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From Knut Anders Hatlen <Knut.Hat...@Sun.COM>
Subject Re: [jira] Updated: (DERBY-3616) TableFunctionTest fails under Ubuntu 7.10
Date Wed, 16 Apr 2008 23:15:04 GMT
Rick Hillegas <Richard.Hillegas@Sun.COM> writes:

> Mike Matrigali wrote:
>> Rick Hillegas wrote:
>>> Thanks, Mike. I don't think I understand what the upgrade issues
>>> are. Could you explain?
>>> Regards,
>>> -Rick
>> I may just have jumped in too soon, as I don't really understand
>> what the encoding that was a problem is actually doing.  I was just
>> working off the info in the bug and saw the word's encoding which
>> felt like something that was going to encode something that went to
>> disk and then would be read from
>> disk later on subsequent database boots.  Anything like that would
>> seem like it might present problems if we have to change the
>> encoding in a new version of the software - so it would be easier to
>> get it "right" now rather than have multiple versions of it.
>> Maybe you could explain what is being encoded and if it is actually ever
>> making it to disk.  From description I was assuming it was in some
>> catalog that held the info about the table function.
> Thanks for digging into this issue, Mike. What's being serialized (and
> encoded) is the signature of a Table Function. This serialized form is
> kept in the in-memory query plan and retrieved from memory when the
> Table Function is instantiated. I don't believe that these plans are
> ever stored on disk. If they were, I agree that we would want to sand
> this down now.

I think we store the compiled plans on disk if they are used in
triggers. Could we call the table functions from triggers?

Anyway, I think this only means that we can't change the format on the
10.4 branch. Stored prepared statements are invalidated when we upgrade
the database to a higher minor version, so we won't see any problems if
the format is changed on trunk.

Knut Anders

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