[GitHub] [pinot] xiangfu0 edited a comment on pull request #7678: Fixing DISTINCT with AS function

[GitBox <gi...@apache.org>]

xiangfu0 edited a comment on pull request #7678:
URL: https://github.com/apache/pinot/pull/7678#issuecomment-958651669


   > > > > > I don't think we should introduce `AS` as a transform function. The fix should be purely on the query rewrite.
   > > > > > `select CAST(runs AS string) as ddd from baseballStats GROUP BY 1` should be rewritten to `select DISTINCT(CAST(runs AS string)) as ddd from baseballStats` instead of `select DISTINCT(CAST(runs AS string) as ddd) from baseballStats`. Notice the place of `as ddd`.
   > > > > > In fact, `select DISTINCT(CAST(runs AS string) as ddd) from baseballStats` is not a valid SQL query
   > > > > 
   > > > > 
   > > > > True, I think the tricky case here is that distinct can have multiple arguments, e.g.
   > > > > ```
   > > > > select CAST(runs AS string) as a, CAST(num AS int) as b from baseballStats GROUP BY 1, 2
   > > > > ```
   > > > 
   > > > 
   > > > For this query, can we rewrite it to `select CAST(runs AS string) as a, CAST(num AS int) as b, DISTINCT(a, b) from baseballStats`? This way it is still valid SQL
   > > 
   > > 
   > > I think this query `select CAST(runs AS string) as a, CAST(num AS int) as b, DISTINCT(a, b) from baseballStats` actually changes the number of output columns?
   > 
   > This should have the same behavior as `SELECT C1 AS ALIAS_C1, C2 AS ALIAS_C2, ADD(alias_c1, alias_c2) FROM Foo` which you just fixed in #7590. I think the alias part will be ignored
   
   oh, i mean `select CAST(runs AS string) as a, CAST(num AS int) as b, DISTINCT(a, b) from baseballStats`  will output 4 columns(distinct(a,b)  returns two columns? ): a, b, a, b. but we only want 2 columns a, b.
   


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