sql: release leases before running migrations

We fortunately prevent setting cluster settings in a transaction. That means
that we have full control over the access to tables that run during the
transaction which runs a cluster version upgrade. One observation is that
upgrades can take a long time if we leak leases in some way. In #85391 we
add function resolution which results in decriptors now being leased when
you run the following statement because we need to resolve the function:

`SET CLUSTER SETTING version = crdb_internal.node_executable_version()`

Then the test ends up taking 5 minutes +/- 15% for the leases to expire.
The downside here is that you don't get a transactional view of UDFs used
in expressions inside `SET CLUSTER VERSION`. That seems fine to me.

Release note: None

pkg/sql/set_cluster_setting.go

@@ -238,6 +238,7 @@ func (n *setClusterSettingNode) startExec(params runParams) error {
  params.p.EvalContext(),
  params.extendedEvalCtx.Codec.ForSystemTenant(),
  params.p.logEvent,
+ params.p.descCollection.ReleaseLeases,
  )
  if err != nil {
  return err
@@ -317,6 +318,7 @@ func writeSettingInternal(
  evalCtx *eval.Context,
  forSystemTenant bool,
  logFn func(context.Context, descpb.ID, eventpb.EventPayload) error,
+ releaseLeases func(context.Context),
 ) (expectedEncodedValue string, err error) {
  err = execCfg.DB.Txn(ctx, func(ctx context.Context, txn *kv.Txn) error {
  var reportedValue string
@@ -336,6 +338,7 @@ func writeSettingInternal(
  reportedValue, expectedEncodedValue, err = writeNonDefaultSettingValue(
  ctx, execCfg, setting, name, txn,
  user, st, value, forSystemTenant,
+ releaseLeases,
  )
  if err != nil {
  return err
@@ -384,6 +387,7 @@ func writeNonDefaultSettingValue(
  st *cluster.Settings,
  value tree.Datum,
  forSystemTenant bool,
+ releaseLeases func(context.Context),
 ) (reportedValue string, expectedEncodedValue string, err error) {
  // Stringify the value set by the statement for reporting in errors, logs etc.
  reportedValue = tree.AsStringWithFlags(value, tree.FmtBareStrings)
@@ -398,7 +402,9 @@ func writeNonDefaultSettingValue(
  verSetting, isSetVersion := setting.(*settings.VersionSetting)
  if isSetVersion {
  if err := setVersionSetting(
- ctx, execCfg, verSetting, name, txn, user, st, value, encoded, forSystemTenant); err != nil {
+ ctx, execCfg, verSetting, name, txn, user, st, value, encoded,
+ forSystemTenant, releaseLeases,
+ ); err != nil {
  return reportedValue, expectedEncodedValue, err
  }
  } else {
@@ -438,6 +444,7 @@ func setVersionSetting(
  value tree.Datum,
  encoded string,
  forSystemTenant bool,
+ releaseLeases func(context.Context),
 ) error {
  // In the special case of the 'version' cluster setting,
  // we must first read the previous value to validate that the
@@ -534,6 +541,12 @@ func setVersionSetting(
  })
  }
 
+ // If we're here, we know we aren't in a transaction because we don't
+ // allow setting cluster settings in a transaction. We need to release
+ // our leases because the underlying migrations may affect descriptors
+ // we currently have a lease for. We don't need to hold on to any leases
+ // because the code isn't relying on them.
+ releaseLeases(ctx)
  return runMigrationsAndUpgradeVersion(
  ctx, execCfg, user, prev, value, updateVersionSystemSetting,
  )