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jOOQ's understanding of backwards compatibility is inspired by the rules of semantic versioning according to http://semver.org. Those rules impose a versioning scheme [X].[Y].[Z] that can be summarised as follows:
- If a patch release includes bugfixes, performance improvements and API-irrelevant new features, [Z] is incremented by one.
- If a minor release includes backwards-compatible, API-relevant new features, [Y] is incremented by one and [Z] is reset to zero.
- If a major release includes backwards-incompatible, API-relevant new features, [X] is incremented by one and [Y], [Z] are reset to zero.
Backwards-compatibility is important to jOOQ. You've chosen jOOQ as a strategic SQL engine and you don't want your SQL to break.
However, there are some elements of API evolution that would be considered backwards-incompatible in other APIs, but not in jOOQ. As discussed later on in the section about jOOQ's query DSL API, much of jOOQ's API is indeed an internal domain-specific language implemented mostly using Java interfaces. Adding language elements to these interfaces means any of these actions:
- Adding methods to the interface
- Overloading methods for convenience
- Changing the type hierarchy of interfaces
It becomes obvious that it would be impossible to add new language elements (e.g. new SQL functions, new SELECT clauses) to the API without breaking any client code that actually implements those interfaces. Hence, the following rules should be observed:
- jOOQ's DSL interfaces should not be implemented by client code! Extend only those extension points that are explicitly documented as "extendable" (e.g. custom QueryParts).
- Binary compatibility can be expected from patch releases, but not from minor releases as it is not practical to maintain binary compatibility in an internal DSL.
- Source compatibility can be expected from patch and minor releases.
- Behavioural compatibility can be expected from patch and minor releases.
- Any jOOQ SPI
XYZthat is meant to be implemented ships with a
AbstractXYZ, which can be used safely as a default implementation.
While a reasonable amount of care is spent to maintain these two modules under the rules of semantic versioning, it may well be that minor releases introduce backwards-incompatible changes. This will be announced in the respective release notes and should be the exception.