GeezerVison

Linked Issue

We reject all programs that use <, <=, >=, > or implicit forms of these (e.g., BETWEEN) involving ROW-typed values.
We still allow ORDER BY of ROW values, and sorting of ROW ARRAY values.

Fixes #7652

Checklist

• Unit tests added/updated
• Integration tests added/updated
• Documentation updated
• Changelog updated

Breaking Changes?

• Feldera SQL (Syntax, Semantics)

Describe Incompatible Changes

We now reject programs comparing ROW values. We already used to forbid comparing ROW values for equality, now we also forbid comparing them for ordering. This will make some the compiler reject some user program that were compiled previously.

The reason for this incompatible change is that our implementation of comparison does not match the standard SQL semantics. SQL expects ROW comparisons to use ternary logic, where NULL compared with anything is NULL. Our previous implementation used to produce a non-nullable Boolean results, and was treating NULL as the smallest value of the field type.

The rationale for rejecting such operations is the same as for equality: instead of providing results for such programs that do not match the SQL standard, we prefer to reject such programs.

In SQL ORDER BY uses a different ordering than < or LEAST. That's the reason we actually support ORDER BY on ROW values - it does match our semantics.