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From "Roman Kondakov (JIRA)" <j...@apache.org>
Subject [jira] [Created] (IGNITE-11756) SQL: implement a table row count statistics for the local queries
Date Tue, 16 Apr 2019 12:55:00 GMT
Roman Kondakov created IGNITE-11756:
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             Summary: SQL: implement a table row count statistics for the local queries
                 Key: IGNITE-11756
                 URL: https://issues.apache.org/jira/browse/IGNITE-11756
             Project: Ignite
          Issue Type: Improvement
          Components: sql
            Reporter: Roman Kondakov


Row count statistics should help the H2 optimizer to select the better query execution plan. Currently
the row count supplied to H2 engine is hardcoded value == 10000 (see {{org.h2.index.Index#getRowCountApproximation}}). 
As a first step we can provide an actual table size in the case of local query. To prevent
counting size on each invocation we can cache row count value and invalidate it in some cases:
 * Rebalancing
 * Multiple updates (after the initial loading)
 * On timeout (i.e. 1 minute)



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