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MAJOR: All releases with the same major version number will have API compatibility, defined as [1]. Major version numbers will remain stable over long periods of time. For instance, 1.X.Y may last 1 year or more.

MINOR: Minor releases will typically contain new features and improvements. The target frequency for minor releases is every 3-4 months. One change we'd like to make is to announce fixed release dates and merge windows for each release, to facilitate coordination. Each minor release will have a merge window where new patches can be merged, a QA window when only fixes can be merged, then a final period where voting occurs on release candidates. These windows will be announced immediately after the previous minor release to give people plenty of time, and over time, we might make the whole release process more regular (similar to Ubuntu). At the bottom of this document is anexample window for the 1.0.0 releaseThe current merge window is listed here.

MAINTENANCE: Maintenance releases will occur more frequently and depend on specific patches introduced (e.g. bug fixes) and their urgency. In general these releases are designed to patch bugs. However, higher level libraries may introduce small features, such as a new algorithm, provided they are entirely additive and isolated from existing code paths. Spark core may not introduce any features.

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