Carter Shanklin created HIVE-12311:
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Summary: explain CTAS fails if the table already exists
Key: HIVE-12311
URL: https://issues.apache.org/jira/browse/HIVE-12311
Project: Hive
Issue Type: Bug
Components: Hive
Affects Versions: 1.2.1
Reporter: Carter Shanklin
Priority: Minor
Explain of a CTAS will fail if the table already exists.
This is an annoyance when you're seeing if a large body of SQL queries will
function by putting explain in front of every query.
{code}
hive> create table temp (x int);
OK
Time taken: 0.252 seconds
hive> create table temp2 (x int);
OK
Time taken: 0.407 seconds
hive> explain create table temp as select * from temp2;
FAILED: SemanticException org.apache.hadoop.hive.ql.parse.SemanticException:
Table already exists: mydb.temp
{code}
If we compare to Postgres "The Zinc Standard of SQL Compliance":
{code}
carter=# create table temp (x int);
CREATE TABLE
carter=# create table temp2 (x int);
CREATE TABLE
carter=# explain create table temp as select * from temp2;
QUERY PLAN
---------------------------------------------------------
Seq Scan on temp2 (cost=0.00..34.00 rows=2400 width=4)
(1 row)
{code}
If the CTAS is something complex it would be nice to see the query plan in
advance.
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