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Posted to issues@ignite.apache.org by "Roman Kondakov (JIRA)" <ji...@apache.org> on 2019/04/16 12:55:00 UTC
[jira] [Assigned] (IGNITE-11756) SQL: implement a table row count
statistics for the local queries
[ https://issues.apache.org/jira/browse/IGNITE-11756?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Roman Kondakov reassigned IGNITE-11756:
---------------------------------------
Assignee: Roman Kondakov
> 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
> Assignee: Roman Kondakov
> Priority: Major
>
> 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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