storage: RangeDescriptor incompatibility with previous versions #38471
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A-kv-distribution
Relating to rebalancing and leasing.
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Code not up to spec/doc, specs & docs deemed correct. Solution expected to change code/behavior.
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danhhz
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Jun 26, 2019
38465: roachpb: Change RangeDescriptor.StickyBit and ReplicaDescriptor.Type to nullable r=jeffrey-xiao a=jeffrey-xiao On a mixed version cluster, only having #38302 does not guarantee backwards compatibility for non-nullable fields in RangeDescriptor. Suppose the replicas of a range are of mixed version and the current leaseholder of the range is on newest version. If the leaseholder splits that range and writes to the non-nullable fields in RangeDescriptor and the leaseholder transfers to a node on an older version without #38302, then all CPuts would fail on that node. We must guarantee that #38302 is on all nodes before making the fields in RangeDescriptor non-nullable. Fixes #36983. Fixes #38471. Release note: None Co-authored-by: Jeffrey Xiao <[email protected]>
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Jun 27, 2019
38465: roachpb: Change RangeDescriptor.StickyBit and ReplicaDescriptor.Type to nullable r=jeffrey-xiao a=jeffrey-xiao On a mixed version cluster, only having #38302 does not guarantee backwards compatibility for non-nullable fields in RangeDescriptor. Suppose the replicas of a range are of mixed version and the current leaseholder of the range is on newest version. If the leaseholder splits that range and writes to the non-nullable fields in RangeDescriptor and the leaseholder transfers to a node on an older version without #38302, then all CPuts would fail on that node. We must guarantee that #38302 is on all nodes before making the fields in RangeDescriptor non-nullable. Fixes #36983. Fixes #38471. Release note: None Co-authored-by: Jeffrey Xiao <[email protected]>
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#38147 and #38004 both introduced an incompatibility with old versions of cockroach where RangeDescriptors could no longer be updated. This is because we were using CPut with a proto as the expected value, which is A Bad Idea (see #38302 for why). #38302 tried to fix this by CPut'ing bytes when updating RangeDescriptors. It fixed the new node reading RangeDescriptor written by an old node, but didn't fix an old node reading a RangeDescriptor written by a new node. This means we can't run mixed clusters with old versions of cockroach (splits, replica addition, replica movement, etc are broken).
This is blocking the 19.2.0-alpha.20190701 release
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