[jira] [Created] (ASTERIXDB-1495) Secondary Index-only scan without any predicate

["Taewoo Kim (JIRA)" <ji...@apache.org>]

Taewoo Kim created ASTERIXDB-1495:
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             Summary: Secondary Index-only scan without any predicate
                 Key: ASTERIXDB-1495
                 URL: https://issues.apache.org/jira/browse/ASTERIXDB-1495
             Project: Apache AsterixDB
          Issue Type: Improvement
            Reporter: Taewoo Kim


Currently, the optimizer chooses a secondary index when a selection (or join) predicate exists on a field with a secondary index. An index-only scan will be applied soon based on this optimization. However, it still requires a selection predicate such as the following query. Let's assume we have a secondary B+Tree index on price.

for $o in dataset MugShot
where $o.price > 10
return {"SK":$o.price, "PK":$o.id} 

So, it will be a further improvement if we support a secondary index-only scan without any predicates such as the following query.  Like the above query, we don't need to go through the primary index and this will save a lot of time. Of course, we need to consider whether the secondary key field is nullable or not to provide the correct answer.

for $o in dataset MugShot
return {"SK":$o.price, "PK":$o.id} 




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