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I'd like to run statements like
SELECT date_add('2008-12-31', 1) FROM DUAL
Does Hive (running on Amazon EMR) have something similar?
793
In many other databases, the query engine supports select directly from constant values without specifying a table name. In Hive, there is no system table named Dual.
It is a table that is automatically created by Oracle Database along with the data dictionary. DUAL is in the schema of the user SYS but is accessible by the name DUAL to all users. It has one column, DUMMY, defined to be VARCHAR2(1), and contains one row with a value X.
An external table is a table for which Hive does not manage storage. If you delete an external table, only the definition in Hive is deleted. The data remains. An internal table is a table that Hive manages. If you delete an internal table, both the definition in Hive and the data are deleted.
Not yet: https://issues.apache.org/jira/browse/HIVE-1558
32
Best solution is not to mention table name.
select 1+1;
Gives the result 2. But poor Hive need to spawn map reduce to find this!
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