[
https://issues.apache.org/jira/browse/DRILL-4956?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15800073#comment-15800073
]
ASF GitHub Bot commented on DRILL-4956:
---------------------------------------
Github user paul-rogers commented on a diff in the pull request:
https://github.com/apache/drill/pull/666#discussion_r94704798
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/planner/sql/handlers/ViewHandler.java
---
@@ -74,36 +74,51 @@ public PhysicalPlan getPlan(SqlNode sqlNode) throws
ValidationException, RelConv
final SchemaPlus defaultSchema = context.getNewDefaultSchema();
final AbstractSchema drillSchema =
SchemaUtilites.resolveToMutableDrillSchema(defaultSchema,
createView.getSchemaPath());
- final String schemaPath = drillSchema.getFullSchemaName();
final View view = new View(newViewName, viewSql,
newViewRelNode.getRowType(),
SchemaUtilites.getSchemaPathAsList(defaultSchema));
- final Table existingTable =
SqlHandlerUtil.getTableFromSchema(drillSchema, newViewName);
+ validateViewCreationPossibility(drillSchema, newViewName,
createView.getReplace());
+
+ final boolean replaced = drillSchema.createView(view);
+ final String summary = String.format("View '%s' %s successfully in
'%s' schema",
+ createView.getName(), replaced ? "replaced" : "created",
drillSchema.getFullSchemaName());
+
+ return DirectPlan.createDirectPlan(context, true, summary);
+ }
+
+ /**
+ * Validates if view can be created in indicated schema:
+ * checks if object (persistent / temporary table) with the same exists
+ * in indicated schema, or if view exists but replace flag is not set.
+ *
+ * @param drillSchema schema where views will be created
+ * @param viewName view name
+ * @param replaceView replace view if exists
+ * @throws UserException if views can be created in indicated schema
+ */
+ private void validateViewCreationPossibility(AbstractSchema
drillSchema, String viewName, boolean replaceView) {
--- End diff --
So what happens?
```
CREATE TEMPORARY TABLE foo AS ...
CREATE VIEW bar AS SELECT * FROM foo;
```
Logout. Log back in:
```
SELECT * FROM bar;
```
The above fails, right?
```
CREATE TEMPORARY TABLE foo AS ...
SELECT * FROM bar;
```
Does this now succeed? If so, this raises another issue:
```
USE `my-schema`; // contains table foo
CREATE VIEW bar AS SELECT * FROM foo;
SELECT * FROM bar;
```
This selects data from `my-schema.foo`. Fine.
```
CREATE TEMPORARY TABLE foo AS ...
SELECT * FROM bar;
```
Does the existing view bar now resolve to the temp table `foo`? Or, does it
remember that it used to resolve to the prior `my-schema.foo`?
This seems like a usability hole. It is one thing to change the meaning of
```
SELECT * FROM foo;
```
After I create a temp table of the same name: clearly I saw table names and
knew what I was doing. But, table names in views are hidden.
So, is a solution to forbid the use of temporary tables in creating views?
> Temporary tables support
> ------------------------
>
> Key: DRILL-4956
> URL: https://issues.apache.org/jira/browse/DRILL-4956
> Project: Apache Drill
> Issue Type: Improvement
> Affects Versions: 1.8.0
> Reporter: Arina Ielchiieva
> Assignee: Arina Ielchiieva
> Labels: doc-impacting
> Fix For: Future
>
>
> Link to design doc -
> https://docs.google.com/document/d/1gSRo_w6q2WR5fPx7SsQ5IaVmJXJ6xCOJfYGyqpVOC-g/edit
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