Hi Bhavya, Sorry I am not sure if I fully understand your question.
Let me try to answer it according to my understanding: 1. Through RelColumnMDOrigins, we can get the RelColumnOrigin object, which includes a RelOptTable object. 2. The table scan also has a RelOptTable object, and all table scans of the plan can be found (e.g. through a visitor) 3. With the information of 1 and 2, given any output column, we can get to know it is derived from which columns from which table scans. 4. With the information of 3, given a table scan, we can get to know which column is never used in any output columns, and such columns can be pruned. Best, Liya Fan On Mon, Dec 21, 2020 at 11:31 PM Bhavya Aggarwal <bha...@knoldus.com> wrote: > Hi Liya, > > I had a look at the RelColumnMDOrigins and it is useful in determining > which columns are from which table but still I am not sure how can I get > the column information for TableScan without the rules. If you have any > specific example where we have used this approach will be really helpful to > me. > > Thanks and regards > Bhavya > > On Mon, Dec 21, 2020 at 5:53 PM Fan Liya <liya.fa...@gmail.com> wrote: > > > Hi Bhavya, > > > > IMO, to solve the problem from a global view, the following steps needs > to > > be taken: > > > > 1. Generate a physical plan in the original way (without considering > column > > pruning in the table scan) > > 2. Modify all the table scans in the plan with the RelColumnMDOrigins > > utility (the details have been described above) > > 3. Post process the plan with one of the following ways: > > a) a plan visitor that adjusts other operators in the tree. > > b) a light-weight planner (Hep or Volcano with limited rule sets) > > > > Run the query with the finally generated plan. > > > > Best, > > Liya Fan > > > > > > On Mon, Dec 21, 2020 at 3:33 PM Bhavya Aggarwal <bha...@knoldus.com> > > wrote: > > > > > Hi Fan, > > > > > > I looked at the class RelColumnMDOrigins and it is giving me the origin > > of > > > the column, but even if I want to take it as a global decision I am not > > > sure how to proceed. Can you please elaborate on how to achieve this ? > I > > am > > > literally stuck as I do not want to use so many rules as in any case I > > have > > > to pass these to the TableScan, even if the user does a select * from > > > table, I need to add all those columns to the table scan. > > > > > > Regards > > > Bhavya > > > > > > -- > > > Your feedback matters - At Knoldus we aim to be very professional in > our > > > quality of work, commitment to results, and proactive communication. If > > > you > > > feel otherwise please share your feedback > > > <https://forms.gle/Ax1Te1DDpirAQuQ8A> and we would work on it. > > > > > > > > -- > *Bhavya Aggarwal* > CTO & Partner > Knoldus Inc. <http://www.knoldus.com/> > +91-9910483067 > Canada - USA - India - Singapore > <https://in.linkedin.com/company/knoldus> <https://twitter.com/Knolspeak> > <https://www.facebook.com/KnoldusSoftware/> <https://blog.knoldus.com/> > > -- > Your feedback matters - At Knoldus we aim to be very professional in our > quality of work, commitment to results, and proactive communication. If > you > feel otherwise please share your feedback > <https://forms.gle/Ax1Te1DDpirAQuQ8A> and we would work on it. >
