Re: Re - new datablade announced for informix

Mark Townsend <markbtownsend_at_comcast.net> wrote:
> > I've deliberatly cross-posted in case I'm talking crap, to give experts
> > in the other DBMSs the chance to correct me.
>
> Well, I'm no expert, but Oracle does have a published extensibility
> framework, that does allow for new indexes, operators and optimizer
> directives to be added to the language. This is extensively used within
> Oracle to develop things such as intermedia, spatial etc. There is not a
> lot of third-party uptake of this capability, however, although some did
> - for instance
> http://www.daylight.com/dayhtml/doc/sql/daycart_indexes.html

Unfortunately, building a Daylight index on a table causes all inserts and deletes on that table, and all updates of the column which is indexed, to become serialized at the table level. This is because the extensibility framework does not seem to be powerful enough to allow for the complex undo management needed for ACID index management. If you are making something which is essentially a wrapper around an Oracle internal index type (Like intermedia, which uses, IIRC, an IOT as the real index structure), this is fine. But if you need a fundamentally new index type, it will be difficult or impossible to make it both efficient and ACID.

Xho

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