[CT-691] why isn't postgres_get_relations double-underscored?

[dataders]

for dbt-greenplum, @markporoshin wants to inherit this macro without copying it. is there a reason it isn't double-underscored? Currently, the workaround is to modify this line in impl.py

dbt-core/plugins/postgres/dbt/adapters/postgres/impl.py

Lines 15 to 16 in 10b27b9

	# note that this isn't an adapter macro, so just a single underscore
	GET_RELATIONS_MACRO_NAME = "postgres_get_relations"

to be this:

GET_RELATIONS_MACRO_NAME = "greenplum_get_relations"

but I don't know why!

dbt-core/plugins/postgres/dbt/include/postgres/macros/relations.sql

Line 1 in 10b27b9

{% macro postgres_get_relations () -%}

[jtcohen6]

@dataders I don't think there's a very good reason :) want to change it?

(We should leave the old macro name in place, in case anyone has overridden it by that name, to avoid breaking changes in upgrade.)

My best guess: for "internal" macros, which are specific to one adapter, and shouldn't accidentally interfere with real adapter dispatch, we opted for normal-ish snake case names, rather than the dunder prefix. See, for instance, dbt_snowflake_validate_get_incremental_strategy. But it makes it impossible to use actual dispatch functionality!

For what it's worth, this has caused me some slight issues when working on the "experimental package" for materialized views as well, since that requires a minor alteration to postgres_get_relations.

[github-actions]

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[dbeatty10]

@alzaar thanks for trying to find a good_first_issue to make your first contributions to this repo.

@dataders is this issue still relevant? If so, then @alzaar would like to try resolving it.

[alzaar]

Thanks @dbeatty10 In terms of any pre-reqs, is there anything I need to know before I get started (from the dbt docs) ? I would also like to know how can I replicate the usage locally.

[dbeatty10]

@alzaar you can set up your machine for local development using our contributing instructions (which include a local Postgres database using Docker).

Then you can create a local dbt project via dbt init or some other means. Run dbt debug to make sure the connection is working.

Create this file:
analyses/test_macro.sql

{% set result = postgres_get_relations() %}

{% if execute %}
{% do result.print_table() %}
{% endif %}

Run it and see the results:

dbt compile -s test_macro

After you've done your implementation, then you should be able to change postgres_get_relations within analyses/test_macro.sql to either be get_relations or postgres__get_relations and it should work.

[dbeatty10]

@alzaar if you've never run a dbt project before, then this repo is a quick way to get a first experience.