settings/cluster: introducing the 19.2 cluster version

This is not a backport; it's original work on the release-19.2 branch.
The corresponding work on master is #41931.

I've had to skip a test because it was validating that we've removed all
the versions introduced before 19.1, since they're now "always active".
Work to remove those versions is in progress on master.

Release note: None

Author: andreimatei

docs/generated/settings/settings.html

@@ -134,6 +134,6 @@
 <tr><td><code>trace.debug.enable</code></td><td>boolean</td><td><code>false</code></td><td>if set, traces for recent requests can be seen in the /debug page</td></tr>
 <tr><td><code>trace.lightstep.token</code></td><td>string</td><td><code></code></td><td>if set, traces go to Lightstep using this token</td></tr>
 <tr><td><code>trace.zipkin.collector</code></td><td>string</td><td><code></code></td><td>if set, traces go to the given Zipkin instance (example: '127.0.0.1:9411'); ignored if trace.lightstep.token is set</td></tr>
-<tr><td><code>version</code></td><td>custom validation</td><td><code>19.1-11</code></td><td>set the active cluster version in the format '<major>.<minor>'</td></tr>
+<tr><td><code>version</code></td><td>custom validation</td><td><code>19.2</code></td><td>set the active cluster version in the format '<major>.<minor>'</td></tr>
 </tbody>
 </table>

pkg/server/version_cluster_test.go

@@ -134,11 +134,35 @@ func setupMixedCluster(
 }
 
 // Prev returns the previous version of the given version.
-// eg. prev(2.0) = 1.0, prev(2.1) == 2.0, prev(2.1-5) == 2.1.
+// eg. prev(20.1) = 19.2, prev(19.2) = 19.1, prev(19.1) = 2.1,
+// prev(2.0) = 1.0, prev(2.1) == 2.0, prev(2.1-5) == 2.1.
 func prev(version roachpb.Version) roachpb.Version {
 	if version.Unstable != 0 {
 		return roachpb.Version{Major: version.Major, Minor: version.Minor}
-	} else if version.Minor != 0 {
+	}
+
+	v19_1 := roachpb.Version{Major: 19, Minor: 1}
+
+	if v19_1.Less(version) {
+		if version.Minor > 1 {
+			return roachpb.Version{Major: version.Major, Minor: version.Minor - 1}
+		}
+		// Here we assume that there's going to only be 2 releases per year.
+		// Otherwise we'd need to keep some history of what releases we've had.
+		return roachpb.Version{Major: version.Major - 1, Minor: 2}
+	}
+
+	if version == v19_1 {
+		return roachpb.Version{Major: 2, Minor: 1}
+	}
+
+	// Logic for versions below 19.1.
+
+	if version.Major > 2 {
+		log.Fatalf(context.TODO(), "can't compute previous version for %s", version)
+	}
+
+	if version.Minor != 0 {
 		return roachpb.Version{Major: version.Major}
 	} else {
 		// version will be at least 2.0-X, so it's safe to set new Major to be version.Major-1.

pkg/settings/cluster/cockroach_versions.go

@@ -46,6 +46,7 @@ const (
 	VersionAtomicChangeReplicas
 	VersionTableDescModificationTimeFromMVCC
 	VersionPartitionedBackup
+	Version19_2
 
 	// Add new versions here (step one of two).
 
@@ -551,6 +552,11 @@ var versionsSingleton = keyedVersions([]keyedVersion{
 		Key:     VersionPartitionedBackup,
 		Version: roachpb.Version{Major: 19, Minor: 1, Unstable: 11},
 	},
+	{
+		// Version19_2 is CockroachDB v19.2. It's used for all v19.2.x patch releases.
+		Key:     Version19_2,
+		Version: roachpb.Version{Major: 19, Minor: 2},
+	},
 
 	// Add new versions here (step two of two).
 

pkg/settings/cluster/cockroach_versions_test.go

@@ -18,6 +18,8 @@ import (
 )
 
 func TestVersionsAreValid(t *testing.T) {
+	t.Skip("test skipped on the release 19.2 branch because we haven't " +
+		"removed old migrations introduced in 19.1")
 	defer leaktest.AfterTest(t)()
 
 	require.NoError(t, versionsSingleton.Validate())

pkg/settings/cluster/versionkey_string.go

@@ -289,7 +289,7 @@ select crdb_internal.set_vmodule('')
 query T
 select regexp_replace(crdb_internal.node_executable_version()::string, '(-\d+)?$', '');
 ----
-19.1
+19.2
 
 query ITTT colnames
 select node_id, component, field, regexp_replace(regexp_replace(value, '^\d+$', '<port>'), e':\\d+', ':<port>') as value from crdb_internal.node_runtime_info
@@ -442,7 +442,7 @@ select * from crdb_internal.gossip_alerts
 query T
 select regexp_replace(crdb_internal.node_executable_version()::string, '(-\d+)?$', '');
 ----
-19.1
+19.2
 
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