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From "Taras Ledkov (JIRA)" <j...@apache.org>
Subject [jira] [Created] (IGNITE-10781) Add supportion findNext for H2TreeIndex to use H2 optimization for DISTINCT
Date Fri, 21 Dec 2018 11:39:00 GMT
Taras Ledkov created IGNITE-10781:
-------------------------------------

             Summary: Add supportion findNext for H2TreeIndex to use H2 optimization for DISTINCT
                 Key: IGNITE-10781
                 URL: https://issues.apache.org/jira/browse/IGNITE-10781
             Project: Ignite
          Issue Type: Improvement
          Components: sql
    Affects Versions: 2.7
            Reporter: Taras Ledkov


Now {{H2TreeIndex}} doesn't implement the method {{BaseIndex#findNext}}.

This method is used by H2 engine in the [optimization of the DISTINCT|https://www.h2database.com/javadoc/org/h2/engine/DbSettings.html#OPTIMIZE_DISTINCT].

To enable this optimization we have to implement the *findNext* method.
Also we have provide selectivity info for the distinct column, because the optimization is
enabled only when column selectivity < 0,2 (and column selectivity isn't default).



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