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From Timo Walther <twal...@apache.org>
Subject Handling of system attributes in a row
Date Wed, 15 Feb 2017 08:56:22 GMT
Hi everyone,

we (from Flink) are currently discussing how we can express 
time-semantics (event-time or processing-time) in a SQL query. The 
optimal solution would be to have two system attributes that are part of 
every table schema/every row data type. We could then access it like 
`SELECT * FROM MyTable ORDER BY rowtime`. However, it should not be part 
of the result in an expansion (`*`) and the user should not modify those 
attributes (no aliasing, read-only). I had a look into SqlValidator and 
there are several lines that contain things like `includeSystemVars` or 
`isSystemField` but nothing concrete. Am I right that this feature is 
not entirely implemented yet? Which parts would you touch/override to 
implement this feature?

Thanks in advance.

Regards,
Timo




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