May need to be a new type of metadata (i.e. a class that implements Metadata 
and is acquired via RelMetadataQuery) [1] [2].

Julian

[1] 
https://calcite.apache.org/apidocs/org/apache/calcite/rel/metadata/Metadata.html
 
<https://calcite.apache.org/apidocs/org/apache/calcite/rel/metadata/Metadata.html>
 

[2] 
https://calcite.apache.org/apidocs/org/apache/calcite/rel/metadata/package-summary.html
 
<https://calcite.apache.org/apidocs/org/apache/calcite/rel/metadata/package-summary.html>
 

> On Nov 18, 2019, at 5:40 PM, Madhav Suresh <[email protected]> wrote:
> 
> Hi All,
> 
> We have security type information that we want to bring into the optimizer.
> Consider the query:
> SELECT a FROM a,b where a.id=b.id AND a.p > 10;
> We want the optimizer to know that a.id, b.id are "public" attributes, and
> a.p is a private attribute. Currently we have type information stored
> inform information_schema in postgres. Right now our prototype considers
> privacy as a RelTrait. We are stuck on what the best way to read this
> information is. Is there a similar example, or template on how to read in
> table metadata into calcite?
> 
> Madhav

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