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https://issues.apache.org/jira/browse/CALCITE-1748?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15966891#comment-15966891
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Julian Hyde commented on CALCITE-1748:
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Calcite gets schema via an SPI. That SPI does not assume that the whole schema
is present.
> Make CalciteCatalogReader.getSchema extendable to support dynamically load
> schema tree - getSchema need to be set to protected to allow overriding
> --------------------------------------------------------------------------------------------------------------------------------------------------
>
> Key: CALCITE-1748
> URL: https://issues.apache.org/jira/browse/CALCITE-1748
> Project: Calcite
> Issue Type: Bug
> Reporter: Chunhui Shi
> Assignee: Julian Hyde
>
> In system like Drill, there is a need to load partial schema (e.g. for only
> one storage plugin) only when needed. Since Drill has no way to get a full
> available schema tree before hand, nor could Drill cache available schema for
> a storage plugin(e.g. Hive, MongoDB) since the storage plugin may not have
> notification mechanism to update Schema tree timely.
>
> The proposed fix is to load schema dynamically as shown in
> https://issues.apache.org/jira/browse/DRILL-5089
> To achieve this, we need to make CalciteCatalogReader.getSchema to be
> protected so it could be overridden by derived class while the derived class
> can reuse other functionalities in CalciteCatalogReader class
> private CalciteSchema getSchema(Iterable<String> schemaNames,
> SqlNameMatcher nameMatcher)
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