sync requirements for sorting with JPQL

[gavinking]

this is a traditional restriction on the 'order by' clause

see section 4.10 of latest JPA 3.2 specification

[njr-11]

This clears up an issue that I tried to raise while reviewing the JDQL pull. I remember asking about the order of evaluation of the clauses and how SELECT could be done before ORDER BY when SELECT might restrict the available entity attributes such that some aren't available for ORDER BY to sort on. What you added in this pull causes the section that I was asking about to make more sense now.

[gavinking]

This clears up an issue that I tried to raise while reviewing the JDQL pull. I remember asking about the order of evaluation of the clauses and how SELECT could be done before ORDER BY when SELECT might restrict the available entity attributes such that some aren't available for ORDER BY to sort on. What you added in this pull causes the section that I was asking about to make more sense now.

OK, cool, yes, I remember the discussion. And yeah, strictly-speaking you're right that if projection happens before sorting then you can't sort by columns which are projected away. In actually practice I ignore this restriction all the time with no ill effects. But here we should be more careful.