dawidwys commented on a change in pull request #8404: [FLINK-11476][table]
Create CatalogManager to manage multiple catalogs
URL: https://github.com/apache/flink/pull/8404#discussion_r286074850
##########
File path:
flink-table/flink-table-api-java/src/main/java/org/apache/flink/table/api/TableEnvironment.java
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@@ -280,6 +315,142 @@
*/
void sqlUpdate(String stmt, QueryConfig config);
+ /**
+ * Gets the current default catalog name of the current session.
+ *
+ * @return The current default catalog name that is used for the path
resolution.
+ * @see TableEnvironment#useCatalog(String)
+ */
+ String getCurrentCatalog();
+
+ /**
+ * Sets the current catalog to the given value. It also sets the default
+ * database to the catalog's default one. To assign both catalog and
database explicitly
+ * see {@link TableEnvironment#useDatabase(String, String)}.
+ *
+ * <p>This is used during the resolution of object paths. Both the
catalog and database are optional
+ * when referencing catalog objects(tables, views etc.). The algorithm
looks for requested objects in following
+ * paths in that order:
+ * <ol>
+ * <li>{@code
[current-catalog].[current-database].[requested-path]}</li>
+ * <li>{@code [current-catalog].[requested-path]}</li>
+ * <li>{@code [requested-path]}</li>
+ * </ol>
+ *
+ * <p>Example:
+ *
+ * <p>Given structure with default catalog set to {@code
default-catalog} and default database set to
+ * {@code default-database}.
+ * <pre>
+ * root:
+ * |- default-catalog
+ * |- default-database
+ * |- tab1
+ * |- db1
+ * |- tab1
+ * |- cat1
+ * |- db1
+ * |- tab1
+ * </pre>
+ *
+ * <p></p>The following table describes resolved paths:
+ * <table>
+ * <thead>
+ * <tr>
+ * <th>Requested path</th>
+ * <th>Resolved path</th>
+ * </tr>
+ * </thead>
+ * <tbody>
+ * <tr>
+ * <td>tab1</td>
+ * <td>default-catalog.default-database.tab1</td>
+ * </tr>
+ * <tr>
+ * <td>db1.tab1</td>
+ * <td>default-catalog.db1.tab1</td>
+ * </tr>
+ * <tr>
+ * <td>cat1.db1.tab1</td>
+ * <td>cat1.db1.tab1</td>
+ * </tr>
+ * </tbody>
+ * </table>
+ *
+ * @param catalogName The name of the catalog to set as the current
default catalog.
+ * @throws CatalogException thrown if a catalog with given name could
not be set as the default one
+ */
+ void useCatalog(String catalogName);
+
+ /**
+ * Gets the current default database name of the running session.
+ *
+ * @return The name of the current database of the current catalog.
+ * @see TableEnvironment#useDatabase(String, String)
+ */
+ String getCurrentDatabase();
+
+ /**
+ * Sets the current default catalog and database. That path will be
used as the default one
+ * when looking for unqualified object names.
+ *
+ * <p>This is used during the resolution of object paths. Both the
catalog and database are optional
+ * when referencing catalog objects(tables, views etc.). The algorithm
looks for requested objects in following
+ * paths in that order:
+ * <ol>
+ * <li>{@code
[current-catalog].[current-database].[requested-path]}</li>
+ * <li>{@code [current-catalog].[requested-path]}</li>
+ * <li>{@code [requested-path]}</li>
+ * </ol>
+ *
+ * <p>Example:
+ *
+ * <p>Given structure with default catalog set to {@code
default-catalog} and default database set to
+ * {@code default-database}.
+ * <pre>
+ * root:
+ * |- default-catalog
+ * |- default-database
+ * |- tab1
+ * |- db1
+ * |- tab1
+ * |- cat1
+ * |- db1
+ * |- tab1
+ * </pre>
+ *
+ * <p></p>The following table describes resolved paths:
+ * <table>
+ * <thead>
+ * <tr>
+ * <th>Requested path</th>
+ * <th>Resolved path</th>
+ * </tr>
+ * </thead>
+ * <tbody>
+ * <tr>
+ * <td>tab1</td>
+ * <td>default-catalog.default-database.tab1</td>
+ * </tr>
+ * <tr>
+ * <td>db1.tab1</td>
+ * <td>default-catalog.db1.tab1</td>
+ * </tr>
+ * <tr>
+ * <td>cat1.db1.tab1</td>
+ * <td>cat1.db1.tab1</td>
+ * </tr>
+ * </tbody>
+ * </table>
+ *
+ * @param catalogName The name of the catalog to set as the current
catalog.
+ * @param databaseName The name of the database to set as the current
database.
+ * @throws CatalogException thrown if the given catalog and database
could not be set as the default ones
+ */
+ void useDatabase(
+ String catalogName,
Review comment:
It is, sort of. Underneath they translate to:
```
useCatalog = CatalogManager.setCatalog
useDatabase = CatalogManager.setCatalog + CatalogManager.setDatabase
```
I think it makes sense to leave it as it is, as the alternative would be to
provide just `useDatabase(databaseName)`. I find this method error prone
though. As the catalog name would be implicit.
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