Got it. Thanks Julian! On Tue, Apr 18, 2017 at 2:02 PM, Julian Hyde <[email protected]> wrote:
> In Calcite we call that a "system column". > > I don't recall whether there's support in the validator to add system > columns; if not, it could be added. > > In Oracle only base tables can have system columns (not even views). > But in Calcite any relational operator can have them. For instance, > streaming join is able to add a rowtime system column. Hence the > Join.getSystemFieldList() method. > > On Tue, Apr 18, 2017 at 8:39 AM, Jacques Nadeau <[email protected]> > wrote: > > James, thanks for the reminder on EXTENDS. And Julian, thanks for the > > reminder of the _MAP, that must have been what I was remembering. I'm > > actually looking for something slightly different: > > > > I want a column to exists for validation when explicitly requested but be > > excluded from star expansion. Any other ideas on how to handle this? > Think > > ROWNUM in Oracle. I guess they call it a pseudocolumn. > > > > On Mon, Apr 17, 2017 at 11:49 PM, Julian Hyde <[email protected]> wrote: > > > >> There’s also the “_MAP” column returned by the MongoDB and Elasticsearch > >> adapters. It contains a (key, value) pair for the top-level fields of > each > >> row. It DOES appear in SELECT *. > >> > >> We had the idea of rewriting > >> > >> SELECT empno FROM Emp > >> > >> to > >> > >> SELECT _MAP[‘empno’] FROM Emp > >> > >> if Emp had a particular row type but I don’t think we ever did it. > >> > >> Julian > >> > >> > >> > >> > >> > On Apr 17, 2017, at 7:27 PM, James Taylor <[email protected]> > >> wrote: > >> > > >> > Hey Jacques, > >> > The EXTENDS (col1 type, col2 type) keyword can be used for this (and > the > >> > EXTENDS keyword is optional). Something like this in Phoenix: > >> > > >> > SELECT foo FROM bar (my_col VARCHAR) WHERE my_col = 'bas' > >> > > >> > Phoenix uses this for dynamic column support. > >> > > >> > Thanks, > >> > James > >> > > >> > On Mon, Apr 17, 2017 at 7:17 PM, Jacques Nadeau <[email protected]> > >> wrote: > >> > > >> >> Hey All, > >> >> > >> >> I remember there being a syntax in Calcite that allowed one to > define an > >> >> _EXTRA column or columns that could be referenced in Calcite but > >> wouldn't > >> >> be included in a select *. If I recall, the Splunk adapter used this > at > >> one > >> >> point. Does this actually exist or have I lost my mind. I can't seem > to > >> >> find a reference to this anywhere. > >> >> > >> >> thanks! > >> >> > >> > >> >
