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Posted to dev@ignite.apache.org by "Taras Ledkov (JIRA)" <ji...@apache.org> on 2018/12/21 11:39:00 UTC
[jira] [Created] (IGNITE-10781) Add supportion findNext for
H2TreeIndex to use H2 optimization for DISTINCT
Taras Ledkov created IGNITE-10781:
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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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