Modify output for table_info command in rel table

[prrao87]

Currently, we need to run 3 CALL statements to retrieve the primary key info from the node tables so that we know how to construct the correct export query for the rel table.

CALL table_info(Node1)
RETURN *;

CALL table_info(Node2)
RETURN *;

CALL table_info(Rel)
RETURN *;

The first two show us the primary keys for the node tables. Simply exporting the rel table with all properties of the node table (or skipping the node tables entirely) isn't useful.

Current

When we output the table info for a rel table, it only outputs the relationship properties, but no node primary key info (which would be helpful to output the rel table).

kuzu> CALL table_info("Rel") RETURN *;
--------------------------------------------
| property id | name           | type      |
--------------------------------------------
| 1           | id | INT64     |
--------------------------------------------
| 2           | example_prop     | STRING     |
--------------------------------------------

Desired

We could output the src and dest primary keys from the underlying rel table information.

kuzu> CALL table_info("Rel") RETURN *;
--------------------------------------------
| property id | name           | type      |
--------------------------------------------
| 1           | id | INT64     |
--------------------------------------------
| 2           | example_prop     | STRING     |
--------------------------------------------

src: Node1, primary_key: id
dest: Node2, primary_ley: id

This would allow the user to obtain just enough information via a single CALL statement to output the rel table with the node primary keys via a subsequent COPY TO command.

[semihsalihoglu-uw]

Consider assigning this to @manh9203 @mxwli or @MSebanc as well during times they need an issue to take care of.

[manh9203]

@prrao87 I found it's tricky to fit these information into the result of table_info, or maintain them outside the result, so I modified show_connection to display them instead.
Now we can get information for exporting rel table using 2 queries:

• CALL show_connection('rel_table') to get the name of nodes and their primary key
• CALL table_info('rel_table') to get the name of the table's properties

[prrao87]

Ok, will document this accordingly (after I test).