[ http://issues.apache.org/jira/browse/DERBY-619?page=all ]
Mike Matrigali updated DERBY-619:
---------------------------------
Component: SQL
Store
Implementation would require changes both to the store Qualifier interface and
to the language level to generate the new Qualifiers. We could push all
qualifier processing into store, but I am not sure that is the best model.
Currently the qualifier processing is done in store at a very low level while
holding a latch on the page. The restriction of a single column allows the
optimization of processing the columns in order on the page and one can stop
getting columns if a qualifier fails. Once multiple columns are required it
gets much more complicated, and it probably best to just select all the columns
into the row buffer and then run the qualifiers. Once the row has been read
into memory there is not much overhead in language running the qualiffier vs.
store, especially if group fetch is being used.
Before we add multiple column qualifiers, I would rather see other qualifier
improvements like IN list processing.
> Make scan Qualifiers smart enough to handle comparisons between columns in
> the same row
> ---------------------------------------------------------------------------------------
>
> Key: DERBY-619
> URL: http://issues.apache.org/jira/browse/DERBY-619
> Project: Derby
> Type: Improvement
> Components: SQL, Store
> Reporter: Rick Hillegas
>
> Right now we can push the following restriction fragment into the Store: "col
> < CONSTANT". It would be good if we could also push "col1 < col2" into the
> Store. Same goes for =, !=, >, etc..
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