Removed the support for dateless timestamps.
During dateless timestamp casts if the format doesn't contain
date part we get an error during tokenization of the format.
If the input str doesn't contain a date part then we get null result.
Examples:
select cast('01:02:59' as timestamp);
This will come back as NULL value.
select to_timestamp('01:01:01', 'HH:mm:ss');
select cast('01:02:59' as timestamp format 'HH12:MI:SS');
select cast('12 AM' as timestamp FORMAT 'AM.HH12');
These will come back with a parsing errors.
Casting from a table will generate similar results.
Testing:
Modified the previous tests related to dateless timestamps.
Added test to read fromtables which are still containing dateless
timestamps and covered timestamp to string path when no date tokens
are requested in the output string.
Change-Id: I48c49bf027cc4b917849b3d58518facba372b322
Reviewed-on: http://gerrit.cloudera.org:8080/15866
Tested-by: Impala Public Jenkins <impala-public-jenkins@cloudera.com>
Reviewed-by: Gabor Kaszab <gaborkaszab@cloudera.com>
This change allows casting of a string in 'lazy' date/time
format to timestamp. The supported lazy date formats are:
yyyy-[M]M-[d]d
yyyy-[M]M-[d]d [H]H:[m]m:[s]s[.SSSSSSSSS]
[H]H:[m]m:[s]s[.SSSSSSSSS]
We will incur a SCAN performance penalty (approximately 1/2
TotalReadThroughput) when the string is in one of these
lazy date/time format.
Testing:
Benchmarked the performance consequence by executing this SQL on
a private build over 3.8 billion rows:
select min(cast (time_string as timestamp)) from private.impala_5315
Added tests for valid and invalid date/time format strings
in expr-test.cc to be inline with existing tests for CAST() function.
Added end-to-end tests into exprs.test and
select-lazy-timestamp.test to exercise the new function within
the context of a query.
Added tests to exercise the leading and trailing white space trimming
behaviour in default and lazy date/time string format (IMPALA-6630).
Change-Id: Ib9a184a09d7e7783f04d47588537612c2ecec28f
Reviewed-on: http://gerrit.cloudera.org:8080/7009
Reviewed-by: Tim Armstrong <tarmstrong@cloudera.com>
Tested-by: Impala Public Jenkins
