Merge #86246 #86944

86246: sql: Implement DISCARD TEMP r=rafiss a=e-mbrown

Refs #83061

Release note (sql change): We now support DISCARD TEMP/TEMPORARY, which drops all temporary tables created in the current session. The command does not drop temporary schemas.

Release note (bug fix): DISCARD ALL now deletes temporary tables

Release justification: Low risk, high benefit changes to existing functionality(DISCARD ALL)

86944: batcheval: fix incorrect StartTime in ExportResponse r=stevendanna a=adityamaru

Previously, ExportResponse for a revision history backup
was always setting the `StartTime` in the response to the
GCThreshold of the span being exported. This is correct for
a full backup where revision history stretches only as far back
as the GCThreshold, but is incorrect for incremental backups
where the StartTime should stretch as far back as the StartTime
of the ExportRequest.

Thankfully, this StartTime in ExportResponse is only used for
validating that the restore AOST is greater than the StartTime
of the full backup i.e. this field is inconsequential for incrementals.
Nonetheless, we should send back an accurate response.

Release note: None

Release justification: low risk bug fix

Co-authored-by: e-mbrown <[email protected]>
Co-authored-by: adityamaru <[email protected]>

docs/generated/sql/bnf/discard_stmt.bnf

@@ -1,3 +1,5 @@
 discard_stmt ::=
 	'DISCARD' 'ALL'
 	| 'DISCARD' 'SEQUENCES'
+	| 'DISCARD' 'TEMP'
+	| 'DISCARD' 'TEMPORARY'

docs/generated/sql/bnf/stmt_block.bnf

@@ -84,6 +84,8 @@ deallocate_stmt ::=
 discard_stmt ::=
 	'DISCARD' 'ALL'
 	| 'DISCARD' 'SEQUENCES'
+	| 'DISCARD' 'TEMP'
+	| 'DISCARD' 'TEMPORARY'
 
 grant_stmt ::=
 	'GRANT' privileges 'ON' grant_targets 'TO' role_spec_list opt_with_grant_option

pkg/kv/kvserver/batcheval/cmd_export.go

@@ -137,7 +137,10 @@ func evalExport(
 	// BACKUP to correctly note the supported time bounds for RESTORE AS OF SYSTEM
 	// TIME.
 	if args.MVCCFilter == roachpb.MVCCFilter_All {
-		reply.StartTime = cArgs.EvalCtx.GetGCThreshold()
+		reply.StartTime = args.StartTime
+		if args.StartTime.IsEmpty() {
+			reply.StartTime = cArgs.EvalCtx.GetGCThreshold()
+		}
 	}
 
 	var exportAllRevisions bool

pkg/sql/discard.go

@@ -48,6 +48,7 @@ func (n *discardNode) startExec(params runParams) error {
 
 		// RESET ALL
 		if err := params.p.resetAllSessionVars(params.ctx); err != nil {
+
 			return err
 		}
 
@@ -59,13 +60,44 @@ func (n *discardNode) startExec(params runParams) error {
 			m.data.SequenceState = sessiondata.NewSequenceState()
 			m.initSequenceCache()
 		})
+
+		// DISCARD TEMP
+		err := deleteTempTables(params.ctx, params.p)
+		if err != nil {
+			return err
+		}
+
 	case tree.DiscardModeSequences:
 		params.p.sessionDataMutatorIterator.applyOnEachMutator(func(m sessionDataMutator) {
 			m.data.SequenceState = sessiondata.NewSequenceState()
 			m.initSequenceCache()
 		})
+	case tree.DiscardModeTemp:
+		err := deleteTempTables(params.ctx, params.p)
+		if err != nil {
+			return err
+		}
 	default:
 		return errors.AssertionFailedf("unknown mode for DISCARD: %d", n.mode)
 	}
 	return nil
 }
+
+func deleteTempTables(ctx context.Context, p *planner) error {
+	codec := p.execCfg.Codec
+	descCol := p.Descriptors()
+	allDbDescs, err := descCol.GetAllDatabaseDescriptors(ctx, p.Txn())
+	if err != nil {
+		return err
+	}
+	ie := p.execCfg.InternalExecutor
+
+	for _, dbDesc := range allDbDescs {
+		schemaName := p.TemporarySchemaName()
+		err = cleanupSchemaObjects(ctx, p.execCfg.Settings, p.Txn(), descCol, codec, ie, dbDesc, schemaName)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}

pkg/sql/logictest/testdata/logic_test/discard

@@ -114,3 +114,44 @@ query I
 SELECT nextval('s2')
 ----
 11
+
+statement ok
+SET experimental_enable_temp_tables=on
+
+query I
+SELECT count(*) FROM [SHOW SCHEMAS] WHERE schema_name LIKE 'pg_temp_%'
+----
+0
+
+statement ok
+DISCARD TEMP;
+
+query I
+SELECT count(*) FROM [SHOW SCHEMAS] WHERE schema_name LIKE 'pg_temp_%'
+----
+0
+
+statement ok
+CREATE TEMP TABLE test (a int);
+
+statement ok
+CREATE TEMP TABLE test2 (a uuid);
+
+query T rowsort
+SELECT table_name FROM [SHOW TABLES FROM pg_temp]
+----
+test
+test2
+
+statement ok
+DISCARD TEMP;
+
+query T rowsort
+SELECT table_name FROM [SHOW TABLES FROM pg_temp]
+----
+
+#Ensure temp schema is not deleted
+query I
+SELECT count(*) FROM [SHOW SCHEMAS] WHERE schema_name LIKE 'pg_temp_%'
+----
+1

pkg/sql/parser/parse_test.go

@@ -450,8 +450,6 @@ func TestUnimplementedSyntax(t *testing.T) {
 		{`DROP TRIGGER a`, 28296, `drop`, ``},
 
 		{`DISCARD PLANS`, 0, `discard plans`, ``},
-		{`DISCARD TEMP`, 0, `discard temp`, ``},
-		{`DISCARD TEMPORARY`, 0, `discard temp`, ``},
 
 		{`SET CONSTRAINTS foo`, 0, `set constraints`, ``},
 		{`SET foo FROM CURRENT`, 0, `set from current`, ``},

pkg/sql/parser/sql.y

@@ -4816,8 +4816,14 @@ discard_stmt:
   {
     $$.val = &tree.Discard{Mode: tree.DiscardModeSequences}
   }
-| DISCARD TEMP { return unimplemented(sqllex, "discard temp") }
-| DISCARD TEMPORARY { return unimplemented(sqllex, "discard temp") }
+| DISCARD TEMP
+  {
+    $$.val = &tree.Discard{Mode: tree.DiscardModeTemp}
+  }
+| DISCARD TEMPORARY
+  {
+    $$.val = &tree.Discard{Mode: tree.DiscardModeTemp}
+  }
 | DISCARD error // SHOW HELP: DISCARD
 
 // %Help: DROP

pkg/sql/sem/tree/discard.go

@@ -26,6 +26,9 @@ const (
 
 	// DiscardModeSequences represents a DISCARD SEQUENCES statement
 	DiscardModeSequences
+
+	// DiscardModeTemp represents a DISCARD TEMPORARY statement
+	DiscardModeTemp
 )
 
 // Format implements the NodeFormatter interface.
@@ -35,6 +38,8 @@ func (node *Discard) Format(ctx *FmtCtx) {
 		ctx.WriteString("DISCARD ALL")
 	case DiscardModeSequences:
 		ctx.WriteString("DISCARD SEQUENCES")
+	case DiscardModeTemp:
+		ctx.WriteString("DISCARD TEMPORARY")
 	}
 }