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https://issues.apache.org/jira/browse/CALCITE-5068?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17516183#comment-17516183
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Julian Hyde commented on CALCITE-5068:
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I think that behavior is probably OK. If DBMS doesn't have a notion of catalog
(e.g. Oracle has only schemas) then the {{Connection.setCatalog}} method will
assign to the 'current catalog' variable but it will be ignored. The
{{TABLE_CATALOG}} field in the output of {{{}getSchemas{}}}, {{{}getTables{}}},
{{getColumns}} etc. is correctly the empty string because the objects don't
have a catalog (or, more precisely, belong to the one and only catalog, whose
name is "").
Perhaps Calcite or CalciteMetaImpl could allow you to specify whether you want
to be a catalog-less DB (only schemas), or a schema-less DB (only catalogs), a
two-level DB (catalogs and schemas but no sub-schemas), or a ragged DB (no
depth restriction on schemas, and tables can occur at any depth, but only
tables at depth 2 are visible through JDBC.
> There are some problems with the use of catalog
> -----------------------------------------------
>
> Key: CALCITE-5068
> URL: https://issues.apache.org/jira/browse/CALCITE-5068
> Project: Calcite
> Issue Type: Bug
> Reporter: itxiangkui
> Priority: Major
>
> when i use under sqlline
> ````shell
> !schema
> !tables
> !metadata getSchemas
> ````
> When I wait for the command, I find that the catalog seems to be a wrong meta
> information, and it is always empty, even after I call
> connection.setCatalog().
> Looking at the source code, found org.apache.calcite.jdbc.CalciteMetaImpl's
>
> ```java
> Enumerable<MetaSchema> schemas(final String catalog) {
> return Linq4j.asEnumerable(
> getConnection().rootSchema.getSubSchemaMap().values())
> .select((Function1<CalciteSchema, MetaSchema>) calciteSchema ->
> new CalciteMetaSchema(calciteSchema, catalog,
> calciteSchema.getName()))
> .orderBy((Function1<MetaSchema, Comparable>) metaSchema ->
> (Comparable) FlatLists.of(Util.first(metaSchema.tableCatalog, ""),
> metaSchema.tableSchem));
> }
> ```
> Obviously, the parameters of the catalog are not used for filtering, and
> there is no context information of the catalog in the rootSchema. The catalog
> is directly passed to the CalciteMetaSchema object.
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