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From "Till (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (ASTERIXDB-1779) Processing the certain function predicates after a simple predicates
Date Thu, 02 Feb 2017 00:16:51 GMT

    [ https://issues.apache.org/jira/browse/ASTERIXDB-1779?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15849159#comment-15849159
] 

Till commented on ASTERIXDB-1779:
---------------------------------

I think that there are no strict reasons anywhere. However, we should be able to succinctly
describe to a user of our system how we come up with a query plan. 
So far we've used (I think) the order of occurrence in a query as a hint. Now we could change
that to ignore the order and only respect it, if the user provides another hint. 
Certainly doable, but yet another line in the description. I'm not sure what the right answer
is.
If we do introduce some for of cost, I think that we should also have some guidelines to determine
if a function is expensive (and not just a list of functions that seems expensive now).

> Processing the certain function predicates after a simple predicates
> --------------------------------------------------------------------
>
>                 Key: ASTERIXDB-1779
>                 URL: https://issues.apache.org/jira/browse/ASTERIXDB-1779
>             Project: Apache AsterixDB
>          Issue Type: Improvement
>            Reporter: Taewoo Kim
>            Assignee: Taewoo Kim
>
> For example, if we have the following AQL query,
> {code}
> for $i in dataset MyData
>    where $i.id < 5 and edit-distance($i.name, "Arnold") < 2
>    return $i;
> {code}
> It may be better to process *$i.id < 5* predicate first and then process *edit-distance($i.name,
"Arnold")* predicate since the processing cost of the latter is higher than that of the former.
 



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