Normalized flat foreign-key row shape consumed by BaseSqlExternalDataSourceDriver.groupForeignKeys.
Each row pairs one referencing column with its referenced column; a composite key spans multiple rows
sharing a constraint_name. SQL drivers map their dialect-specific catalog rows into this shape so the
grouping logic lives once in the shared base.
Normalized flat foreign-key row shape consumed by BaseSqlExternalDataSourceDriver.groupForeignKeys. Each row pairs one referencing column with its referenced column; a composite key spans multiple rows sharing a
constraint_name. SQL drivers map their dialect-specific catalog rows into this shape so the grouping logic lives once in the shared base.