Change 'timestamp' to '_timestamp_' for Apache Kylin compatibility

[lucky2you]

The query is failed when make Apache Kylin as the datasource. The 'timestamp' is a key word in Kylin SQL. So the query "select xxx as timestamp ..." failed. Change 'timestamp' to 'timestamp' to avoid that.

[coveralls]

Coverage decreased (-0.03%) to 81.005% when pulling 300f147 on lucky2you:kylin_timestamp into 8135c24 on airbnb:master.

[coveralls]

Coverage decreased (-0.03%) to 81.005% when pulling 43ef8e1 on lucky2you:kylin_timestamp into 8135c24 on airbnb:master.

[rocky1001]

Hi may be you can try the Caravel-Kylin branch (based on Caravel 0.8.9):
https://github.com/rocky1001/caravel/tree/caravel-kylin
which solved most problems when integrated with Kylin.

[mrbungie]

We're trying to connect to a Teradata MPP and we're having the same problem, since 'timestamp' is a reserved keyword. +1

[lucky2you]

@rocky1001 thanks , it helps a lot! Would you commit your changes to the official repository?

[rocky1001]

@lucky2you If you reviewed the adapter-code in the caravel-kylin branch, you can see the solutions right now is not that good. I'd like to move all the adapter-code to ORM level( in Pykylin ), but really lack of time to finish this.

[mistercrunch]

This LGTM, I just need to test it against our production DB and make sure all is right.

[mistercrunch]

Superseded by https://github.com/airbnb/superset/pull/1590/files