GitHub user cloud-fan opened a pull request:
https://github.com/apache/spark/pull/8698
[SPARK-10442][SQL][WIP] fix string to boolean cast
When we cast string to boolean in hive, it returns `true` if the length of
string is > 0, and spark SQL follows this behavior.
However, this behavior is very different from other SQL systems:
1.
[presto](https://github.com/facebook/presto/blob/master/presto-main/src/main/java/com/facebook/presto/type/VarcharOperators.java#L89-L118)
will return `true` for 't' 'true' '1', `false` for 'f' 'false' '0', throw
exception for others.
2.
[redshift](http://docs.aws.amazon.com/redshift/latest/dg/r_Boolean_type.html)
will return `true` for 't' 'true' 'y' 'yes' '1', `false` for 'f' 'false' 'n'
'no' '0', null for others.
3.
[postgresql](http://www.postgresql.org/docs/devel/static/datatype-boolean.html)
will return `true` for 't' 'true' 'y' 'yes' 'on' '1', `false` for 'f' 'false'
'n' 'no' 'off' '0', throw exception for others.
4. [vertica](https://my.vertica.com/docs/5.0/HTML/Master/2983.htm) will
return `true` for 't' 'true' 'y' 'yes' '1', `false` for 'f' 'false' 'n' 'no'
'0', null for others.
5.
[impala](http://www.cloudera.com/content/cloudera/en/documentation/cloudera-impala/latest/topics/impala_boolean.html)
throw exception when try to cast string to boolean.
6. mysql, oracle, sqlserver don't have boolean type
Whether we should change the cast behavior according to other SQL system or
not is not decided yet, this PR is a test to see if we changed, how many
compatibility tests will fail.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/cloud-fan/spark string2boolean
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/8698.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #8698
----
commit e7b50f63f4edc938636c7cfaf9ba0ba6461c1812
Author: Wenchen Fan <[email protected]>
Date: 2015-09-10T11:58:35Z
fix string to boolean cast
----
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