Using Apache Calcite to query postgres like database

[Shiv K]

Hi team

I am trying to get started with Apache Calcite and do not have very strong
java development skills.

I am trying below, while the first print - prints out the list of tables -
once added to rootSchema - the subsequent print from rootSchema object
prints blank. I do not understand why this is the case.

           Schema schema = JdbcSchema.create(rootSchema, "db1", ds,
                    null, "public");
            Set<String> listTables = schema.getTableNames();
            System.out.println("Tables are " + listTables);

            rootSchema.add("db1", schema);
            Set<String> listTables1 = rootSchema.getTableNames();
            System.out.println("Tables are " + listTables1);

Kindly provide guidance on building the schema and getting started
with parsing queries using Apache Calcite. I have tried going through many
examples on the web - however while I see a lot of calls to the calcite
classes - there are no examples that include validation of the executed
statements and hence I am still in the process of figuring out how to
use Apache Calcite for query parsing and execution.

Your guidance and support will be greatly appreciated!

Thanks much and regards
Shiva