Two phase index builds are a 4.4-only feature. We should not allow a FCV downgrade to 4.2 if there are still index builds in progress. This avoids propagating a commitIndexBuild/abortIndexBuild oplog entry to the secondary node if the index builds completes after the FCV update is done.
- is related to
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SERVER-44468 Enable characterize_index_builds_on_restart.js for two-phase index builds
- Closed