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https://issues.apache.org/jira/browse/CALCITE-911?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14960137#comment-14960137
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Julian Hyde commented on CALCITE-911:
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Regarding SchemaPlus and SchemaPlusImpl. SchemaPlus is intended to be used by
users -- it appears as a parameter in several SPI methods -- but not
instantiated by them. Users should only use the SchemaPlus they are given by
the system. In fact the purpose of SchemaPlus was to expose to user code, in a
read only manner, some of the information in CalciteSchema.
It is analogous to java.sql.Connection.rollback(Savepoint), which can only be
called with a Savepoint created by the same Connection.
> Make CalciteSchema extendible for different implementation.
> -----------------------------------------------------------
>
> Key: CALCITE-911
> URL: https://issues.apache.org/jira/browse/CALCITE-911
> Project: Calcite
> Issue Type: Bug
> Reporter: Jinfeng Ni
> Assignee: Jinfeng Ni
> Fix For: 1.5.0-incubating
>
>
> CalciteSchema by default uses cache to store table, sub-schema, function.
> This would work perfectly for schema-based system, yet would create problem
> for Drill, which dynamically explore the schema on the fly during query
> execution.
> One solution is to refactor CalciteSchema and make it as an interface. The
> default implementation would still use the current implementation. Further,
> it would other system to extend the default behavior and make CalciteSchema
> works for Drill as well.
> Background information: The issue around CalciteSchema is one of the reasons
> that Drill has to use a forked version of Calcite. Hopefully, if we could
> resolve this issue, we are one step further to remove the forked Calcite in
> the near future.
>
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