CREATE VIEW followup: impose casts on view result columns if underlying column
types change
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Key: HIVE-1067
URL: https://issues.apache.org/jira/browse/HIVE-1067
Project: Hadoop Hive
Issue Type: Improvement
Components: Query Processor
Affects Versions: 0.6.0
Reporter: John Sichi
Assignee: John Sichi
Fix For: 0.6.0
Consider
CREATE TABLE t(i INT);
CREATE VIEW v AS SELECT i FROM t;
ALTER TABLE t REPLACE COLUMNS (i STRING);
SELECT i FROM v;
What will be the result type for i in the final SELECT?
Consensus at code review was that it should be INT (not STRING) since the
CREATE VIEW is supposed to freeze the metadata for the view's result schema.
Note that SQL:2008 ALTER COLUMN SET DATA TYPE doesn't cover this case, because
it doesn't support changing the datatype family. For this case, MySQL produces
VARCHAR rather than INT, and (consistently) DESCRIBE v and INFORMATION_SCHEMA
show VARCHAR as well, so either they are propagating the type change in the
catalog, or dynamically re-deriving it.
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