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Update Graph Diff: old-proposed-update-graph.yaml vs proposed-update-graph.yaml

The graphs are not fully equivalent. Below is every difference found.

memory/stable: IDENTICAL — no differences.

All four DB channels: v1.37.1 edge set differs

All of cockroachdb, mysql, postgres, and spanner are affected.

Graph v1.37.1 edges to
Old v1.38.0, v1.39.1, v1.40.1, v1.42.1, v1.45.4, v1.47.1, v1.48.0, v1.49.2, v1.51.1
New v1.38.0 only

The old code let v1.37.1 skip past v1.38.0; the new waypoint algorithm blocks that because v1.38.0 is now a mandatory stop (waypoint: true).

Phase nodes have broader outgoing edges in the new graph

The old code treated phase nodes as strict "step through me to the immediate next version" nodes. The new waypoint algorithm allows phase nodes to reach any target up to (but not past) the next waypoint. Affected nodes:

  • cockroachdb/stable: v1.30.0-phase1
    • Old: only → v1.30.0
    • New: → v1.30.0 through v1.36.2
  • postgres/stable: v1.14.0-phase2
    • Old: only → v1.14.0
    • New: → v1.14.0 through v1.36.2
  • spanner/stable: v1.22.2-phase2 and v1.29.5-phase1
    • Old: each pointed only to the immediate next version
    • New: each can reach further (up to the v1.38.0 waypoint)

spanner/stable: v1.51.1 node missing from old graph

The old graph encoded the latest spanner version as a quirk: node v1.49.2 had tag: v1.51.1. The new graph correctly has v1.49.2 with tag: v1.49.2 and a separate v1.51.1 node, which adds outgoing edges from all existing spanner nodes to v1.51.1.

Node field differences

Channel Node Field Old value New value
cockroachdb/stable v1.30.0-phase1 phase missing write-both-read-new
spanner/stable v1.29.5-phase1 phase missing write-both-read-new
spanner/stable v1.49.2 tag v1.51.1 v1.49.2

Bottom line

The graphs differ in four ways:

  1. v1.37.1 edge narrowing (all DB channels) — likely correct; v1.38.0 is now a hard waypoint.
  2. Phase-node outgoing edge expansion — semantic change: old code was "phase node → immediate next release only"; new algorithm is "phase node → anything up to the next waypoint". Whether multi-hop skips from a phase node are safe depends on whether those intermediate versions require a migration stop.
  3. spanner/stable v1.51.1 node added — likely a bug fix in the old graph where v1.49.2 was carrying the wrong tag.
  4. phase field missing on phase nodes in old graph — old serialization omitted the phase field from those nodes; new graph includes it.