[GitHub] [calcite] DonnyZone edited a comment on issue #1792: [CALCITE-3775] Implicit lookup methods in SimpleCalciteSchema ignore case sensitivity parameter

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DonnyZone edited a comment on issue #1792: [CALCITE-3775] Implicit lookup methods in SimpleCalciteSchema ignore case sensitivity parameter
URL: https://github.com/apache/calcite/pull/1792#issuecomment-584975246
 
 
   (1) `Schema` interface is provided to users. We'd better not bring much burden to users, even a `default` implementation. Moreover, it is uncertain whether a `Schema`'s concrete implementation (e.g., `JdbcSchema`) can push down case insensitive lookups to underlying datasources.
   Insteadly, `CalciteSchema` is a suitable place to implement case insensitive lookup. From my understanding (correct me if I am wrong), the initial design may be:
   ```
   Schema: interface for users (case sensitive)
      |
   CalciteSchema: wrapper around user-defined schema used internally, providing case (in)sensitive lookups
      |
   CachingCalciteSchema/SimpleCalciteSchema
   ```
   (2) 
   > Most of the implementations should be able to delegate case insensitive requests to NameMap, which would be OK for performance.
   
   I think `CachingCalciteSchema` has already achieved this goal. It caches tables and maintains them in `NameMap`.
   The javadoc of `CachingCalciteSchema` is:
   
   >  * Concrete implementation of {@link CalciteSchema} that caches tables,
   >  * functions and sub-schemas.
   
   While the javadoc of `SimpleCalciteSchema` is
   >  * A concrete implementation of {@link org.apache.calcite.jdbc.CalciteSchema}
   >  * that maintains minimal state.
   
   Therefore, `SimpleCalciteSchema` and `CachingCalciteSchema` play different roles. If we unify them for the seek of performance, we can just remove `SimpleCalciteSchema`.

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