sql: fix usages of ActiveVersionOrEmpty in {create, alter}_table.go

Fixes cockroachdb#45519.

This PR removes an incorrect usage of ActiveVersionOrEmpty in
alter_table.go, and updates a comment in create_table.go detailing its
usage.

Release note: None

pkg/sql/alter_table.go

@@ -346,8 +346,7 @@ func (n *alterTableNode) startExec(params runParams) error {
 
 		case *tree.AlterTableAlterPrimaryKey:
 			// Make sure that all nodes in the cluster are able to perform primary key changes before proceeding.
-			version := params.p.ExecCfg().Settings.Version.ActiveVersionOrEmpty(params.ctx)
-			if !version.IsActive(clusterversion.VersionPrimaryKeyChanges) {
+			if !params.p.ExecCfg().Settings.Version.IsActive(params.ctx, clusterversion.VersionPrimaryKeyChanges) {
 				return pgerror.Newf(pgcode.FeatureNotSupported,
 					"all nodes are not the correct version for primary key changes")
 			}
@@ -358,7 +357,7 @@ func (n *alterTableNode) startExec(params runParams) error {
 			}
 
 			if t.Sharded != nil {
-				if !version.IsActive(clusterversion.VersionHashShardedIndexes) {
+				if !params.p.ExecCfg().Settings.Version.IsActive(params.ctx, clusterversion.VersionHashShardedIndexes) {
 					return invalidClusterForShardedIndexError
 				}
 				if !params.p.EvalContext().SessionData.HashShardedIndexesEnabled {

pkg/sql/create_table.go

@@ -1181,14 +1181,12 @@ func MakeTableDesc(
 	// If all nodes in the cluster know how to handle secondary indexes with column families,
 	// write the new version into new index descriptors.
 	indexEncodingVersion := sqlbase.BaseIndexFormatVersion
-	// We can't use st.Version.IsActive because this method is sometimes called
-	// before the version has been initialized, leading to a panic. There are also
-	// cases where this function is called in tests where st is nil.
-	if st != nil {
-		if version := st.Version.ActiveVersionOrEmpty(ctx); version != (clusterversion.ClusterVersion{}) &&
-			version.IsActive(clusterversion.VersionSecondaryIndexColumnFamilies) {
-			indexEncodingVersion = sqlbase.SecondaryIndexFamilyFormatVersion
-		}
+	// We can't use st.Version.IsActive because this method is used during
+	// server setup before the cluster version has been initialized.
+	version := st.Version.ActiveVersionOrEmpty(ctx)
+	if version != (clusterversion.ClusterVersion{}) &&
+		version.IsActive(clusterversion.VersionSecondaryIndexColumnFamilies) {
+		indexEncodingVersion = sqlbase.SecondaryIndexFamilyFormatVersion
 	}
 
 	for i, def := range n.Defs {
@@ -1210,7 +1208,7 @@ func MakeTableDesc(
 				if st == nil {
 					return desc, invalidClusterForShardedIndexError
 				}
-				if version := st.Version.ActiveVersionOrEmpty(ctx); version == (clusterversion.ClusterVersion{}) ||
+				if version == (clusterversion.ClusterVersion{}) ||
 					!version.IsActive(clusterversion.VersionHashShardedIndexes) {
 					return desc, invalidClusterForShardedIndexError
 				}