[SPARK-16217][SQL] Support SELECT INTO statement

[wuxianxingkong]

What changes were proposed in this pull request?

This PR implements the SELECT INTO statement.

The SELECT INTO statement selects data from one table and inserts it into a new table as follows.

SELECT column_name(s)
INTO newtable
FROM table1;

This statement is commonly used in SQL but not currently supported in SparkSQL.
We investigated the Catalyst and found that this statement can be implemented by improving the grammar and reusing the logical plan of CTAS.

The related JIRA is https://issues.apache.org/jira/browse/SPARK-16217

How was this patch tested?

SQLQuerySuite.

[AmplabJenkins]

Can one of the admins verify this patch?

[dongjoon-hyun]

Hi, @wuxianxingkong .
Currently, the following seems to be not considered yet. Could you modify the syntax to support this too?

SELECT 1
INTO newtable

[wuxianxingkong]

Hello, @dongjoon-hyun , thank you for your advice.

SELECT 1 
INTO newtable

This won't work because we need oldtable info to create newtable. So the sql should be

SELECT 1
INTO newtable 
FROM oldtable

The result from my test is: a new table called newtable was created, one column called 1 has the length of oldtable.rows.length and all elements are 1.
Did you mean there is no FROM?

[dongjoon-hyun]

In the Spark Shell, please run the followings.

sql("select 1")

[wuxianxingkong]

@dongjoon-hyun
At first, I modify grammar:

But it will affect multiInsertQueryBody rule, i.e.:

FROM OLD_TABLE
INSERT INTO T1
SELECT C1
INSERT INTO T2
SELECT C2

The Syntax tree before adding intoClause is:

After adding intoClause ,the tree will be:
This is because INSERT is a nonreserved keyword and matching strategy of antlr.
One of the ways I can think of is to change grammar like this:

This can solve the problem because antlr parser chooses the alternative specified first.
The grammar can support "SELECT 1 INTO newtable" now.
But this will cause confusion about querySpecification rule because of the duplication. Is there any way to make the syntax less verbose?Thanks.

[dongjoon-hyun]

Hi, @wuxianxingkong .
Although I'm just a contributor like you, I left a few comments for you because I like your PR.
I hope your PR will be merged soon.

[hvanhovell]

This allows for the following syntax:

INSERT INTO tbl_a
SELECT *
INTO tbl_a
FROM tbl_b

Make sure that we cannot have both.

[hvanhovell]

We also need to check what this does with multi-insert syntax, i.e.:

FROM tbl_a
INSERT INTO tbl_b
SELECT *
INSERT INTO tbl_c
SELECT *
INTO tbl_c

[gatorsmile]

Why throwing a ParseException ?

[gatorsmile]

@wuxianxingkong Are you still working on this? Thanks!

[gatorsmile]

We are closing it due to inactivity. please do reopen if you want to push it forward. Thanks!