Postgres: support schemas prefixed with "pg"

[BenoitRanque]

Is your proposal related to a problem?

Hasura console does not currently display schemas when the schema name starts with pg.

The postgres documentation states that

Schema names beginning with pg_ are reserved for system purposes and cannot be created by users.

Describe the solution you'd like

Hasura console should show schemas beginning with pg (but not pg_)

[BenoitRanque]

Note this may not be only a console issue.
Creating the metadata manually did not work, and lead to metadata inconsistency due to a missing table (despite the table existing)

[BenoitRanque]

This issue happens at least in part because the introspection query uses the following SQL:

  AND "table".table_schema NOT LIKE 'pg_%'

The _ character is a wildcard, and cant match any character. From the postgres documentation:

An underscore (_) in pattern stands for (matches) any single character

The _ character should be escaped like so:

  AND "table".table_schema NOT LIKE 'pg\_%'

This is most likely an oversight and not intentional.
I am opening a PR to fix this, but I do not believe this will be the end of the story.
Most likely the console also has sql statements with this mistake.

[gautamsi]

I also have same issue, I use https://github.com/timgit/pg-boss which uses schema name pgboss

I wanted to connect hasura to pgboss database and use subscription to create some dashboard but stuck with this specific issue.