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https://issues.apache.org/jira/browse/IGNITE-11756?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16842270#comment-16842270
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Taras Ledkov commented on IGNITE-11756:
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[~rkondakov], my comments:
1. Please think about try to avoid change {{ThreadLocal<QueryContext>}} at the
{{GridH2Table#rowCountForSegment}}
Possible way to refactoring: add new methods for Ignite Index implementations
that receives {{QueryContext}} as an argument.
2. The query plan is generated at the {{H2QueryInfo#H2QueryInfo}} for all
queries. Fast query performance may degrade.
Can we use {{Prepared#getPlanSQL}} from other thread? Is is thread safe?
> 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
> Time Spent: 20m
> Remaining Estimate: 0h
>
> 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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