[Feature] Option to set index storage parameters

[kinghuang]

Is this your first time submitting a feature request?

• [X] I have read the expectations for open source contributors
• [X] I have searched the existing issues, and I could not find an existing issue for this feature
• [X] I am requesting a straightforward extension of existing dbt-postgres functionality, rather than a Big Idea better suited to a discussion

Describe the feature

dbt-postgres supports specifying indexes in model configs with three components: columns, unique, and type. I would like an option to set index storage parameters. This is relevant when creating pgvector hnsw indexes, and other index types.

Describe alternatives you've considered

• Override the postgres__get_create_index_sql macro.
• Use a post-hook.

Who will this benefit?

For pgvector users, being able to specify m and ef_construction storage parameters on hnsw indexes is crucial for performance management. Standard indexes like b-tree, GiST, and GIN also have useful parameters.

Are you interested in contributing this feature?

Not at this time.

Anything else?

No response