Re: Recording foreign key relationships for the system catalogs

Hi again,

After trying to use pg_get_catalog_foreign_keys() to replace what I had before,
I notice one ambiguity which I think is a serious problem in the machine-readable context.

The is_array OUT parameter doesn't say which of the possibly many fkcols that is the array column.

One example:

fktable | fkcols | pktable | pkcols | is_array
----------------------+-----------------------+--------------+-------------------+----------
pg_constraint | {conrelid,conkey} | pg_attribute | {attrelid,attnum} | t

Is the array "conrelid" or is it "conkey"? As a human, I know it's "conkey", but for a machine to figure out, one would need to join information_schema.columns and check the data_type or something similar.

Suggestions on how to fix:

* Make is_array an boolean[], and let each element represent the is_array value for each fkcols element.

* Change interface to be more like information_schema, and add a "ordinal_position" column, and return each column on a separate row.

I think I prefer the latter since it's more information_schema-conformant, but any works.

/Joel