Support # in addition to -- as a default comment prefix for Quartz DataSource initialization

[abccbaandy]

spring boot version : 2.1.6.RELEASE
spring-boot-starter-quartz

quartz-scheduler/quartz#262 (comment)

maybe spring.quartz.jdbc.comment-prefix=# should be default?

[wilkinsona]

The comment prefix is set to -- by default. We can’t change it to # as that will be a breaking change for those relying on it being --. If you require a different comment prefix you will have to configure it. Please see #13160 and #13041 for details.

That said, I wonder if we can do better here. Perhaps we could automatically use a different comment prefix based on the database that is being used.

[philwebb]

I think we also have the same problem with DataSourceInitializer, although it looks like we don't offer a property for setCommentPrefix there.

[wilkinsona]

A small difference between the two is that the scripts used by DataSourceInitializer are typically written by the user and are only intended to be consumed by Boot rather than also by the database itself. That means they can use -- (the SQL standard) and it should always work.

In the Quartz case, the scripts are out of the users control and were, I imagine, primarily written to be read by the database itself rather than a tool like Boot's DataSource initialization. This is not to say that there's no problem with DataSourceInitializer, but I do think it's less likely to be problematic.

[philwebb]

I've submitted a PR to framework that will allow us to support both prefixes spring-projects/spring-framework#23289