Add groupby/aggregation support for PostgreSQL in GraphQL

[Arjun Narendra (ArjunNarendra)]

Why make this change?

Closes #2850. This PR adds support for group by and aggregation in PostgreSQL in GraphQL queries.

What is this change?

Groupby and aggregation types/enums were added to the GraphQL schema in PostgreSQL, but they essentially were orphaned because the user couldn't utilize them in their GraphQL query. This PR hooks up the groupby/aggregation schema types/enums into a GraphQL input query.

How was this tested?

• Integration Tests

Sample Request(s)

query {
  stocks_prices {
    groupBy(fields: [categoryid, pieceid]) {
      fields {
        categoryid
        pieceid
      }
      aggregations {
        total: sum(field: price)
        count: count(field: pieceid, having: { gt: 5 })
      }
    }
  }
}

Previously, a query such as the one above would fail because the groupBy field would not have been attached to the stocks_prices object type. This PR adds the groupBy field to the relevant list query entity types. The groupBy field serves as a window to the rest of the groupBy/aggregation query.

[Copilot]

Pull request overview

This PR enables end-to-end GraphQL groupBy + aggregation support for PostgreSQL by wiring Postgres into the GraphQL schema’s aggregation feature gate and updating the Postgres SQL query builder to emit aggregation columns and GROUP BY/HAVING clauses. It also re-enables the previously ignored PostgreSQL aggregation integration tests and updates the PostgreSQL test schema.

Changes:

• Enable GraphQL aggregation support for DatabaseType.PostgreSQL in the schema builder.
• Extend PostgresQueryBuilder SQL generation to include aggregation columns plus GROUP BY/HAVING/conditional ORDER BY.
• Un-ignore and update PostgreSQL GraphQL aggregation tests; extend PostgreSQL test schema with date_only_table.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/Service.GraphQLBuilder/Queries/QueryBuilder.cs	Enables aggregation/groupBy schema features for PostgreSQL.
src/Core/Resolvers/PostgresQueryBuilder.cs	Adds aggregation + group-by/having clause generation to Postgres SELECT queries.
src/Core/Resolvers/BaseTSqlQueryBuilder.cs	Moves shared group-by/having/order-by/aggregation helpers out of the T-SQL-only base.
src/Core/Resolvers/BaseSqlQueryBuilder.cs	Centralizes shared group-by/having/order-by/aggregation helper methods for all SQL builders.
src/Service.Tests/SqlTests/GraphQLQueryTests/PostgreSqlGraphQLQueryTests.cs	Re-enables and updates PostgreSQL aggregation integration tests and expected SQL baselines.
src/Service.Tests/DatabaseSchema-PostgreSql.sql	Adds/drop support for date_only_table test data.

Comments suppressed due to low confidence (2)

src/Service.Tests/SqlTests/GraphQLQueryTests/PostgreSqlGraphQLQueryTests.cs:633

• This GROUP BY test’s expected SQL omits ORDER BY, but the assertion compares arrays by index. Postgres row order for GROUP BY without ORDER BY is not guaranteed, so the test can be flaky. Add ORDER BY on the group-by fields to make the expected result deterministic.

                    FROM stocks_price
                    GROUP BY categoryid, pieceid
                    HAVING SUM(price) > 50 AND COUNT(pieceid) <= 100
                ) AS table0";

src/Service.Tests/SqlTests/GraphQLQueryTests/PostgreSqlGraphQLQueryTests.cs:653

• This GROUP BY expected SQL has no ORDER BY, but the test compares expected vs actual by position. Since Postgres doesn’t guarantee GROUP BY output order, add an ORDER BY on the group-by keys to avoid nondeterministic failures.

                    FROM stocks_price
                    GROUP BY categoryid, pieceid
                ) AS table0";

[Souvik Ghosh (souvikghosh04)]

Approving, assuming the review comments would be addressed along with test coverages.

[Arpit Gupta (ar-guptaar)]

There is a bug in group by feature wherein if there are mappings present on the columns, the GroupBy workflow does not honor the backed column name.
This impacts both MSSQL & PG workflows.
I have fixed it via the following PR : #3750. This has some regression tests added as well.
My suggestion would be to add some regression tests for PG code path as well (refer PR), that way we can be sure both the paths are working as expected.

CC: Souvik Ghosh (@souvikghosh04) Arjun Narendra (@ArjunNarendra)

[Arjun Narendra (ArjunNarendra)]

There is a bug in group by feature wherein if there are mappings present on the columns, the GroupBy workflow does not honor the backed column name. This impacts both MSSQL & PG workflows. I have fixed it via the following PR : #3750. This has some regression tests added as well. My suggestion would be to add some regression tests for PG code path as well (refer PR), that way we can be sure both the paths are working as expected.

CC: Souvik Ghosh (@souvikghosh04) Arjun Narendra (@ArjunNarendra)

Thanks for catching this, Arpit Gupta (@ar-guptaar). I tested the bug and was able to reproduce it. The fix you propose makes sense. I will add some regression tests here.

[Souvik Ghosh (souvikghosh04)]

Please check the lastest comments

[Anusha Kolan (anushakolan)]

LGTM!