We are not able to get any order by clause
public Enumerable<Object[]> scan(DataContext dataContext, List<RexNode>
filters) {
....
}
In the above function of filterable table we get only the where clause in the
List<RexNode> filters.
For example:
Select * from users order by name limit 100;
In case of above query the filters list is empty.
Select * from users where age > 18 order by name limit 100;
In case of above query the filters list has only the where clause (age > 18).
So, no info about sort, limit or offset if present in the query.
________________________________
From: Mihai Budiu <mbu...@gmail.com>
Sent: Tuesday, September 17, 2024 2:06 PM
To: dev@calcite.apache.org <dev@calcite.apache.org>
Cc: Harshit Dwivedi <harshit.dwiv...@rockwellautomation.com>; Dipesh Sachdev
<dipesh.sach...@rockwellautomation.com>; Thomas Keller <tkel...@ra.rockwell.com>
Subject: EXTERNAL: Re: Questions Regarding Implementing LIMIT Clause Pushdown
in Apache Calcite JDBC Driver
[Use caution with links & attachments]
Isn't limit stored in an order by clause, with potentially an empty list of
fields to sort on?
________________________________
From: Vishal Kore <vishal.k...@rockwellautomation.com.INVALID>
Sent: Tuesday, September 17, 2024 1:17:15 AM
To: dev@calcite.apache.org <dev@calcite.apache.org>
Cc: Harshit Dwivedi <harshit.dwiv...@rockwellautomation.com>; Dipesh Sachdev
<dipesh.sach...@rockwellautomation.com>; Thomas Keller <tkel...@ra.rockwell.com>
Subject: Questions Regarding Implementing LIMIT Clause Pushdown in Apache
Calcite JDBC Driver
Hi Devs,
I am currently working on implementing (or extending) a JDBC driver for my
backend storage system using Apache Calcite. I've implemented the
FilterableTable interface, which allows pushing down WHERE clause filters to
the backend using the scan(DataContext ctx, List<RexNode> filters) method.
However, I'm struggling to push down the LIMIT clause to ensure that only the
required number of records are retrieved from the backend. I cannot figure out
how to access the LIMIT clause within the scan method.
Could you please guide me on how to retrieve or implement the LIMIT clause in
this context?
Thanks for your assistance!
Best regards,
Vishal Kore
