[SPARK-16678] [SPARK-16677] [SQL] Fix two View-related bugs

[gatorsmile]

What changes were proposed in this pull request?

Issue 1: Disallow Creating/Altering a View when the same-name Table Exists (without IF NOT EXISTS)
When we create OR alter a view, we check whether the view already exists. In the current implementation, if a table with the same name exists, we treat it as a view. However, this is not the right behavior. We should follow what Hive does. For example,

hive> CREATE TABLE tab1 (id int);
OK
Time taken: 0.196 seconds
hive> CREATE OR REPLACE VIEW tab1 AS SELECT * FROM t1;
FAILED: SemanticException [Error 10218]: Existing table is not a view
 The following is an existing table, not a view: default.tab1
hive> ALTER VIEW tab1 AS SELECT * FROM t1;
FAILED: SemanticException [Error 10218]: Existing table is not a view
 The following is an existing table, not a view: default.tab1
hive> CREATE VIEW IF NOT EXISTS tab1 AS SELECT * FROM t1;
OK
Time taken: 0.678 seconds

Issue 2: Strange Error when Issuing Load Table Against A View
Users should not be allowed to issue LOAD DATA against a view. Currently, when users doing it, we got a very strange runtime error. For example,

LOAD DATA LOCAL INPATH "$testData" INTO TABLE $viewName

java.lang.reflect.InvocationTargetException was thrown.
java.lang.reflect.InvocationTargetException
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at org.apache.spark.sql.hive.client.Shim_v0_14.loadTable(HiveShim.scala:680)

How was this patch tested?

Added test cases

[viirya]

If allowing existing, do we still need to throw this exception?

[gatorsmile]

Yeah, a good question. Just did a check using Hive. It is allowed by Hive.

hive> CREATE VIEW IF NOT EXISTS tab1 AS SELECT * FROM t1;
OK
Time taken: 0.678 seconds

Let me move this a little bit down.

[SparkQA]

Test build #62712 has finished for PR 14314 at commit 5c9be14.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[SparkQA]

Test build #62716 has finished for PR 14314 at commit c698a4a.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[SparkQA]

Test build #62717 has finished for PR 14314 at commit c64092c.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[gatorsmile]

cc @cloud-fan

[cloud-fan]

what's hive's error message for this case? view already existing or not a view?

[gatorsmile]

For this case, it shows table already existed. However, when we found a view/table exists, the error message is wrong:

View $tableIdentifier already exists. If you want to update the view definition,
 please use ALTER VIEW AS or CREATE OR REPLACE VIEW AS

We are unable to alter a table (that is not a view) by these commands ALTER VIEW AS or CREATE OR REPLACE VIEW AS.

See the source code

The message is better than table already exists, I think.

[gatorsmile]

hive> CREATE VIEW tab1 AS SELECT * FROM t1;
FAILED: Execution Error, return code 1 from org.apache.hadoop.hive.ql.exec.DDLTask. AlreadyExistsException(message:Table tab1 already exists)

[SparkQA]

Test build #62800 has finished for PR 14314 at commit f73d206.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[cloud-fan]

LGTM, waiting for #14297

[SparkQA]

Test build #62825 has finished for PR 14314 at commit 3f7ea99.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[cloud-fan]

thanks, merging to master!