branch-4.0: [fix](cloud) query fails when smooth upgrade primary BE not alive yet #60317 #60470
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…#60317) Root cause: 1. On the same host, old BE (e.g. heartbeat 9050) and new BE (e.g. 9051) run in parallel during smooth upgrade. 2. migrateTablets updates CloudReplica primary from old BE to new BE. At that time the new BE may not have registered or sent heartbeats, so it is not alive in FE. 3. updateClusterToPrimaryBe(clusterId, dstBe) also clears secondary for that cluster, so no fallback BE is left. 4. On query: primary (new BE) is not alive -> getSecondaryBackend() returns null -> code falls back to hashReplicaToBe(). 5. hashReplicaToBe() only considers BEs with be.isQueryAvailable() && !be.isSmoothUpgradeSrc(). The old BE is excluded as smooth-upgrade source; the new BE is excluded because it is not alive. Result: no available BE and COMPUTE_GROUPS_NO_ALIVE_BE. Fix: - After switching primary to the new BE in migrateTablets, set the old BE (srcBe) as secondary for that cluster. - Expose updateClusterToSecondaryBe in CloudReplica so the rebalancer can set this fallback. - Queries then use primary when possible and fall back to secondary (old BE) when primary is not alive; isQueryAvailable() does not exclude the old BE by isSmoothUpgradeSrc(), so the old BE can still serve reads until the new BE becomes alive.
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yiguolei
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Feb 4, 2026
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PR approved by at least one committer and no changes requested. |
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Cherry-picked from #60317