Is there a way to change it to use the DBMS default sort? about blaze-persistence

[beikov]

It is correct that Blaze-Persistence will always generate proper HQL that includes either null first or nulls last if the expression you order by is nullable. This shouldn't be a problem though if the null ordering you use matches the database default. I don't know which database you use, but e.g. H2 and MySQL treat null as the smallest element, so when you sort ascending, then nulls first is the default and for descending sorting, nulls last is the default. PostgreSQL and Oracle for example behave the other way around. There nulls last is the default for asc and nulls first the default for desc. Just match the default.

[beikov]

Hi! There is no option to change the default. That default is encoded into the implementation on purpose, for exactly the reason that you quoted, so that you choose a null precedence that fits your needs :)

[zhanglc]

Hi! There is no option to change the default. That default is encoded into the implementation on purpose, for exactly the reason that you quoted, so that you choose a null precedence that fits your needs :)

@beikov how to choose null precedence ?

[beikov]

You just add a second argument to orderByAsc or orderByDesc that specifies whether nulls should be first/last.

[zhanglc]

Thanks for the reply, is there no way to remove nulls first / nulls last with the current version ?

[beikov]

The only way to not render null first / nulls last in the resulting SQL is by using the same null precedence as the underlying database.

[zhanglc]

@beikov
I'm very sorry to reopen this issue. I found some code that looks like, blaze persistence doesn't support order's null default ?

blaze-persistence/core/impl/src/main/java/com/blazebit/persistence/impl/OrderByManager.java

Lines 527 to 533 in c6f8e2f

	if (nullable) {
	if (orderBy.nullFirst == inverseOrder) {
	sb.append(" NULLS LAST");
	} else {
	sb.append(" NULLS FIRST");
	}
	}

If I pass in a null default, nullFirst is false and the sql will be append with order by A null last.

Am I understanding this correctly?
I want to change this behavior, how do I do it, thank you very much!

[zhanglc]

@beikov thanks a lot .
We use PostgreSQL , It works well as change the code to the ones you've hinted.

Thanks a lot.