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distsql: ensure backward compatibility during upgrade #17277

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RaduBerinde opened this issue Jul 28, 2017 · 5 comments
Closed

distsql: ensure backward compatibility during upgrade #17277

RaduBerinde opened this issue Jul 28, 2017 · 5 comments
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@andreimatei
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C-enhancement Solution expected to add code/behavior + preserve backward-compat (pg compat issues are exception) S-2-temp-unavailability Temp crashes or other availability problems. Can be worked around or resolved by restarting.
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Later

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@RaduBerinde
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The RFC in #16977 describes a mechanism for upgrade without downtime. DistSQL went through some backward incompatible changes; we need to go back through them and fix distsqlrun to provide backward-compatibility, as well as gate use of new features in the planner.

CC @spencerkimball
@RaduBerinde RaduBerinde added this to the 1.1 milestone Jul 28, 2017
@RaduBerinde
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An alternative is to get the changes to tolerate SetupFlow failures by rescheduling the flow on the gateway (#15637). However this is not ideal because during upgrade DistSQL queries might run on a small number of nodes - in the worst case, if 1 node is upgraded, any queries processed by that node will run all the flows on that same node - causing potential query regressions (in terms of how long they take to run, or even if they run at all due to memory usage).

@cuongdo
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cuongdo commented Aug 22, 2017

@RaduBerinde please triage

@RaduBerinde
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Andrei is handling this, PR #17497

@andreimatei
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We're now not planning DistSQL flows on nodes that are running an incompatible version. This should be good for now; I'll defer the fallback stuff for later since it proved to not be so easy.

@andreimatei andreimatei modified the milestones: Later, 1.1 Aug 24, 2017
@knz knz added C-enhancement Solution expected to add code/behavior + preserve backward-compat (pg compat issues are exception) S-2-temp-unavailability Temp crashes or other availability problems. Can be worked around or resolved by restarting. labels Apr 27, 2018
@jordanlewis
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I think the solution we have in place is already good enough.

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@andreimatei andreimatei

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C-enhancement Solution expected to add code/behavior + preserve backward-compat (pg compat issues are exception) S-2-temp-unavailability Temp crashes or other availability problems. Can be worked around or resolved by restarting.
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@jordanlewis @andreimatei @knz @cuongdo @RaduBerinde