sql: add support for materialized views

Fixes #41649.

This commit adds support for materialized views in CockroachDB. These
materialized views follow the Postgres style, where the `REFRESH
MATERIALIZED VIEW` command is needed to update the stored view data.
This commit does not include adding the various `ALTER MATERIALIZED
VIEW` and `DROP MATERIALIZED VIEW` extensions and will be added in a
follow up PR.

Release note (sql change): Add support for materialized views.

docs/generated/settings/settings.html

@@ -72,6 +72,6 @@
 <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>20.1-15</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>20.1-16</code></td><td>set the active cluster version in the format '<major>.<minor>'</td></tr>
 </tbody>
 </table>

docs/generated/sql/bnf/create_view_stmt.bnf

@@ -5,3 +5,5 @@ create_view_stmt ::=
 	| 'CREATE' 'OR' 'REPLACE' opt_temp 'VIEW' view_name  'AS' select_stmt
 	| 'CREATE' opt_temp 'VIEW' 'IF' 'NOT' 'EXISTS' view_name '(' name_list ')' 'AS' select_stmt
 	| 'CREATE' opt_temp 'VIEW' 'IF' 'NOT' 'EXISTS' view_name  'AS' select_stmt
+	| 'CREATE' 'MATERIALIZED' 'VIEW' view_name '(' name_list ')' 'AS' select_stmt
+	| 'CREATE' 'MATERIALIZED' 'VIEW' view_name  'AS' select_stmt

docs/generated/sql/bnf/stmt_block.bnf

@@ -15,6 +15,7 @@ stmt ::=
 	| revoke_stmt
 	| savepoint_stmt
 	| release_stmt
+	| refresh_stmt
 	| nonpreparable_set_stmt
 	| transaction_stmt
 	| close_cursor_stmt
@@ -87,6 +88,9 @@ savepoint_stmt ::=
 release_stmt ::=
 	'RELEASE' savepoint_name
 
+refresh_stmt ::=
+	'REFRESH' 'MATERIALIZED' 'VIEW' view_name
+
 nonpreparable_set_stmt ::=
 	set_transaction_stmt
 
@@ -286,6 +290,9 @@ savepoint_name ::=
 	'SAVEPOINT' name
 	| name
 
+view_name ::=
+	table_name
+
 set_transaction_stmt ::=
 	'SET' 'TRANSACTION' transaction_mode_list
 	| 'SET' 'SESSION' 'TRANSACTION' transaction_mode_list
@@ -871,6 +878,7 @@ unreserved_keyword ::=
 	| 'RECURRING'
 	| 'RECURSIVE'
 	| 'REF'
+	| 'REFRESH'
 	| 'REINDEX'
 	| 'RELEASE'
 	| 'RENAME'
@@ -1160,6 +1168,7 @@ create_view_stmt ::=
 	'CREATE' opt_temp 'VIEW' view_name opt_column_list 'AS' select_stmt
 	| 'CREATE' 'OR' 'REPLACE' opt_temp 'VIEW' view_name opt_column_list 'AS' select_stmt
 	| 'CREATE' opt_temp 'VIEW' 'IF' 'NOT' 'EXISTS' view_name opt_column_list 'AS' select_stmt
+	| 'CREATE' 'MATERIALIZED' 'VIEW' view_name opt_column_list 'AS' select_stmt
 
 create_sequence_stmt ::=
 	'CREATE' opt_temp 'SEQUENCE' sequence_name opt_sequence_option_list
@@ -1635,9 +1644,6 @@ opt_temp ::=
 	| 'TEMP'
 	| 
 
-view_name ::=
-	table_name
-
 sequence_name ::=
 	db_object_name
 

pkg/clusterversion/cockroach_versions.go

@@ -75,6 +75,8 @@ const (
 	VersionMinPasswordLength
 	VersionAbortSpanBytes
 	VersionAlterSystemJobsAddSqllivenessColumnsAddNewSystemSqllivenessTable
+	VersionMaterializedViews
+
 	// Add new versions here (step one of two).
 )
 
@@ -564,6 +566,11 @@ var versionsSingleton = keyedVersions([]keyedVersion{
 		Key:     VersionAlterSystemJobsAddSqllivenessColumnsAddNewSystemSqllivenessTable,
 		Version: roachpb.Version{Major: 20, Minor: 1, Unstable: 15},
 	},
+	{
+		// VersionMaterializedViews enables the use of materialized views.
+		Key:     VersionMaterializedViews,
+		Version: roachpb.Version{Major: 20, Minor: 1, Unstable: 16},
+	},
 
 	// Add new versions here (step two of two).
 

pkg/sql/backfill.go

@@ -164,6 +164,8 @@ func (sc *SchemaChanger) runBackfill(ctx context.Context) error {
 	var constraintsToAddBeforeValidation []descpb.ConstraintToUpdate
 	var constraintsToValidate []descpb.ConstraintToUpdate
 
+	var viewToRefresh *descpb.MaterializedViewRefresh
+
 	tableDesc, err := sc.updateJobRunningStatus(ctx, RunningStatusBackfill)
 	if err != nil {
 		return err
@@ -210,6 +212,8 @@ func (sc *SchemaChanger) runBackfill(ctx context.Context) error {
 				}
 			case *descpb.DescriptorMutation_PrimaryKeySwap, *descpb.DescriptorMutation_ComputedColumnSwap:
 				// The backfiller doesn't need to do anything here.
+			case *descpb.DescriptorMutation_MaterializedViewRefresh:
+				viewToRefresh = t.MaterializedViewRefresh
 			default:
 				return errors.AssertionFailedf(
 					"unsupported mutation: %+v", m)
@@ -225,7 +229,9 @@ func (sc *SchemaChanger) runBackfill(ctx context.Context) error {
 				}
 			case *descpb.DescriptorMutation_Constraint:
 				constraintsToDrop = append(constraintsToDrop, *t.Constraint)
-			case *descpb.DescriptorMutation_PrimaryKeySwap, *descpb.DescriptorMutation_ComputedColumnSwap:
+			case *descpb.DescriptorMutation_PrimaryKeySwap,
+				*descpb.DescriptorMutation_ComputedColumnSwap,
+				*descpb.DescriptorMutation_MaterializedViewRefresh:
 				// The backfiller doesn't need to do anything here.
 			default:
 				return errors.AssertionFailedf(
@@ -234,6 +240,13 @@ func (sc *SchemaChanger) runBackfill(ctx context.Context) error {
 		}
 	}
 
+	// If we were requested to refresh a view, then do so.
+	if viewToRefresh != nil {
+		if err := sc.refreshMaterializedView(ctx, tableDesc, viewToRefresh); err != nil {
+			return err
+		}
+	}
+
 	// First drop constraints and indexes, then add/drop columns, and only then
 	// add indexes and constraints.
 

pkg/sql/catalog/descpb/structured.go

@@ -221,6 +221,12 @@ func (desc *TableDescriptor) IsView() bool {
 	return desc.ViewQuery != ""
 }
 
+// MaterializedView returns whether or not this TableDescriptor is a
+// MaterializedView.
+func (desc *TableDescriptor) MaterializedView() bool {
+	return desc.IsMaterializedView
+}
+
 // IsAs returns true if the TableDescriptor actually describes
 // a Table resource with an As source.
 func (desc *TableDescriptor) IsAs() bool {