The problem here is that identifier 'user' is not only a reserved word, but also represents a special function == current_user() call. The identifier 'user', whether it's quoted or not, could mean either column name or the function call. Without the table alias, it could be ambiguous to sql parser. The table alias informs the parser that this identifier is not a function call, but a regular identifier, thus removes the ambiguity.
This is different from other cases you use quoted reserved word to represent a column name, since those reserved words do not represent a special function, thus no ambiguity. select `update`, `insert` from dfs.tmp.`1.json`; +---------+---------+ | update | insert | +---------+---------+ | abc | 100 | +---------+---------+ On Mon, May 23, 2016 at 10:44 AM, John Omernik <[email protected]> wrote: > Ya, as I am testing, this works, however, the users of the system expect to > be able to use `user` and while I can provide them instructions to use a > table alias, I am very worried that they will forget and since it doesn't > error, but instead puts in a different string, this could lead to bad > downstream results... > > > > > On Mon, May 23, 2016 at 12:41 PM, John Omernik <[email protected]> wrote: > >> I filed https://issues.apache.org/jira/browse/DRILL-4692 >> >> I see an alias would work as a tmp fix, but this should be address (I >> wonder if other words may have a problem too?) >> >> >> >> On Mon, May 23, 2016 at 12:38 PM, Andries Engelbrecht < >> [email protected]> wrote: >> >>> Hmm interesting. >>> >>> As a workaround just use a table alias when referencing the column. >>> >>> >>> Might be good to se if there is a JIRA for this, or file one if not. >>> >>> --Andries >>> >>> > On May 23, 2016, at 10:28 AM, John Omernik <[email protected]> wrote: >>> > >>> > I have data with a field name user. >>> > >>> > When I select, with backticks, it doesn't show the field, but instead my >>> > current logged in user... >>> > >>> > >>> > select CONVERT_FROM(`user`, 'UTF8') as `user` from table limit 10; >>> > >>> > >>> > Shouldn't the backticks allow me to reference the field properly? >>> > >>> > John >>> >>> >>
