Draft: [PoC] Rewrite queries: Filter on Current.organization

What does this MR do and why?

This MR modifies SELECT queries: if Current.organization is set, it will dynamically add WHERE organization_id = <org_id> based on sharding keys.

This is unreviewed and not tested.

Demo

First, Current.organization is not set, so no WHERE-clauses are applied. All 8 Groups are returned.

➜  gitlab git:(poc-query-parsing) gdk rails c
Loading development environment (Rails 7.1.5.1)
[2] pry(main)> Group.count
=> 8
[3] pry(main)> Group.all.map(&:path)
=> ["toolbox", "gitlab-org", "gnuwget", "Commit451", "jashkenas", "flightjs", "twitter", "group2"]

The newest group, group2, is part of My Org Organization. We set Current.organization to this My Org and then, SQL WHERE clause on organization_id is applied. Only 1 Group is now returned:

[4] pry(main)> Current.organization = Organizations::Organization.second
=> #<Organizations::Organization:0x000000031f71acd8>
[5] pry(main)> Group.count
=> 1
[6] pry(main)> Group.all.map(&:path)
=> ["group2"]

Implementation

• The fast pg_query Query Parser is used to decompose the SQL, add the where-clauses if needed, and return the modified SQL statement
• It works for both ActiveRecord as more low-level SQL
• More complex SQL is not yet supported (CTE's)
• The logic is patching Pg::Connection class
• The query rewriting happens AFTER the logs are written: Rails log will show the unmodified query

References

Screenshots or screen recordings

Before	After

How to set up and validate locally

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