A better option would be to have a user-defined function that takes 2 parameters and evaluates to a boolean value. e.g select * from myTable where MyUDF(notColumn, 'value') IS TRUE;
The Storage Plugin that you are developing would need to implement a pushdown rule that looks at the filter condition and if it contains 'MyUDF()', it would pushdown to the scan/reader corresponding to your plugin. On Sat, Apr 7, 2018 at 6:58 PM, Hanumath Rao Maduri <hanu....@gmail.com> wrote: > Hello Ryan, > > Thank you for trying out Drill. Drill/Calcite expects "notColumn" to be > supplied by the underlying scan. > However, I expect that this column will be present in the scan but not past > the filter (notColumn = 'value') in the plan. > In that case you may need to pushdown the filter to the groupScan and then > remove the column projections from your custom groupscan. > > It would be easy for us to guess what could be the issue, if you can post > the logical and physical query plan's for this query. > > Hope this helps. Please do let us know if you have any further issues. > > Thanks, > > > On Sat, Apr 7, 2018 at 2:08 PM, Ryan Shanks <ryan.sha...@softcomcorp.com> > wrote: > > > Hi Drill Dev Team! > > > > I am writing a custom storage plugin and I am curious if it is possible > in > > Drill to pass a filter value, in the form of a where clause, that is not > > related to a column. What I would like to accomplish is something like: > > > > select * from myTable where notColumn = 'value'; > > > > In the example, notColumn is not a column in myTable, or any other table, > > it is just a specific parameter that the storage plugin will use in the > > filtering process. Additionally, notColumn would not be returned as a > > column so Drill needs to not expect it as a part of the 'select *'. I > > created a rule that will push down and remove these non-column filter > > calls, but I need to somehow tell drill/calcite that the filter name is > > valid, without actually registering it as a column. The following error > > occurs prior to submitting any rules: > > > > org.apache.drill.common.exceptions.UserRemoteException: VALIDATION > ERROR: > > From line 1, column 35 to line 1, column 39: Column 'notColumn' not found > > in any table > > > > > > Alternatively, can I manipulate star queries to only return a subset of > > all the columns for a table? > > > > Any insight would be greatly appreciated! > > > > Thanks, > > Ryan > > >
