This commit adds the disable_hoist_projection_in_join_limitation sess…

…ion flag.

Release note: none

pkg/sql/exec_util.go

@@ -3292,6 +3292,10 @@ func (m *sessionDataMutator) SetUnconstrainedNonCoveringIndexScanEnabled(val boo
 	m.data.UnconstrainedNonCoveringIndexScanEnabled = val
 }
 
+func (m *sessionDataMutator) SetDisableHoistProjectionInJoinLimitation(val bool) {
+	m.data.DisableHoistProjectionInJoinLimitation = val
+}
+
 func (m *sessionDataMutator) SetTroubleshootingModeEnabled(val bool) {
 	m.data.TroubleshootingMode = val
 }

pkg/sql/logictest/testdata/logic_test/information_schema

@@ -4686,6 +4686,7 @@ default_transaction_quality_of_service                regular
 default_transaction_read_only                         off
 default_transaction_use_follower_reads                off
 default_with_oids                                     off
+disable_hoist_projection_in_join_limitation           off
 disable_partially_distributed_plans                   off
 disable_plan_gists                                    off
 disallow_full_table_scans                             off

pkg/sql/logictest/testdata/logic_test/pg_catalog

@@ -4171,6 +4171,7 @@ default_transaction_quality_of_service                regular             NULL
 default_transaction_read_only                         off                 NULL      NULL        NULL        string
 default_transaction_use_follower_reads                off                 NULL      NULL        NULL        string
 default_with_oids                                     off                 NULL      NULL        NULL        string
+disable_hoist_projection_in_join_limitation           off                 NULL      NULL        NULL        string
 disable_partially_distributed_plans                   off                 NULL      NULL        NULL        string
 disable_plan_gists                                    off                 NULL      NULL        NULL        string
 disallow_full_table_scans                             off                 NULL      NULL        NULL        string
@@ -4296,6 +4297,7 @@ default_transaction_quality_of_service                regular             NULL
 default_transaction_read_only                         off                 NULL  user     NULL      off                 off
 default_transaction_use_follower_reads                off                 NULL  user     NULL      off                 off
 default_with_oids                                     off                 NULL  user     NULL      off                 off
+disable_hoist_projection_in_join_limitation           off                 NULL  user     NULL      off                 off
 disable_partially_distributed_plans                   off                 NULL  user     NULL      off                 off
 disable_plan_gists                                    off                 NULL  user     NULL      off                 off
 disallow_full_table_scans                             off                 NULL  user     NULL      off                 off
@@ -4416,6 +4418,7 @@ default_transaction_quality_of_service                NULL    NULL     NULL
 default_transaction_read_only                         NULL    NULL     NULL     NULL        NULL
 default_transaction_use_follower_reads                NULL    NULL     NULL     NULL        NULL
 default_with_oids                                     NULL    NULL     NULL     NULL        NULL
+disable_hoist_projection_in_join_limitation           NULL    NULL     NULL     NULL        NULL
 disable_partially_distributed_plans                   NULL    NULL     NULL     NULL        NULL
 disable_plan_gists                                    NULL    NULL     NULL     NULL        NULL
 disallow_full_table_scans                             NULL    NULL     NULL     NULL        NULL

pkg/sql/logictest/testdata/logic_test/show_source

@@ -46,6 +46,7 @@ default_transaction_quality_of_service                regular
 default_transaction_read_only                         off
 default_transaction_use_follower_reads                off
 default_with_oids                                     off
+disable_hoist_projection_in_join_limitation           off
 disable_partially_distributed_plans                   off
 disable_plan_gists                                    off
 disallow_full_table_scans                             off

pkg/sql/opt/xform/join_funcs.go

@@ -1678,9 +1678,15 @@ func (c *CustomFuncs) getfilteredCanonicalScan(
 	return scanExpr, filters, true
 }
 
-// IsCanonicalScanOrSelect returns true if `relation` is a canonical scan or a
-// select from a canonical scan.
-func (c *CustomFuncs) IsCanonicalScanOrSelect(relation memo.RelExpr) (ok bool) {
+// CanHoistProjectInput returns true if a projection of an expression on
+// `relation` is allowed to be hoisted above a parent Join. The preconditions
+// for this are if `relation` is a canonical scan or a select from a canonical
+// scan, or the disable_hoist_projection_in_join_limitation session flag is
+// true.
+func (c *CustomFuncs) CanHoistProjectInput(relation memo.RelExpr) (ok bool) {
+	if c.e.evalCtx.SessionData().DisableHoistProjectionInJoinLimitation {
+		return true
+	}
 	_, _, ok = c.getfilteredCanonicalScan(relation)
 	return ok
 }

pkg/sql/opt/xform/rules/join.opt

@@ -444,7 +444,7 @@
 (InnerJoin
     $left:*
     $proj:(Project
-        $right:* & (IsCanonicalScanOrSelect $right)
+        $right:* & (CanHoistProjectInput $right)
         $projections:* & ^(HasVolatileProjection $projections)
         $passthrough:*
     )
@@ -486,7 +486,7 @@
 (LeftJoin
     $left:*
     (Project
-        $right:* & (IsCanonicalScanOrSelect $right)
+        $right:* & (CanHoistProjectInput $right)
         $projections:* & ^(HasVolatileProjection $projections)
         $passthrough:*
     )

pkg/sql/sessiondatapb/local_only_session_data.proto

@@ -272,6 +272,10 @@ message LocalOnlySessionData {
   // much a non-production setting.
   double testing_optimizer_disable_rule_probability = 73;
 
+  // disable_hoist_projection_in_join_limitation disables the restrictions
+  // placed on projection hoisting during query planning in the optimizer.
+  bool disable_hoist_projection_in_join_limitation = 74;
+
   ///////////////////////////////////////////////////////////////////////////
   // WARNING: consider whether a session parameter you're adding needs to  //
   // be propagated to the remote nodes. If so, that parameter should live  //

pkg/sql/vars.go

@@ -2014,7 +2014,6 @@ var varGen = map[string]sessionVar{
 		},
 		GlobalDefault: globalFalse,
 	},
-
 	// CockroachDB extension.
 	`show_primary_key_constraint_on_not_visible_columns`: {
 		GetStringVal: makePostgresBoolGetStringValFn(`show_primary_key_constraint_on_not_visible_columns`),
@@ -2120,6 +2119,22 @@ var varGen = map[string]sessionVar{
 			return formatFloatAsPostgresSetting(0)
 		},
 	},
+	// CockroachDB extension.
+	`disable_hoist_projection_in_join_limitation`: {
+		GetStringVal: makePostgresBoolGetStringValFn(`disable_hoist_projection_in_join_limitation`),
+		Set: func(_ context.Context, m sessionDataMutator, s string) error {
+			b, err := paramparse.ParseBoolVar("disable_hoist_projection_in_join_limitation", s)
+			if err != nil {
+				return err
+			}
+			m.SetDisableHoistProjectionInJoinLimitation(b)
+			return nil
+		},
+		Get: func(evalCtx *extendedEvalContext) (string, error) {
+			return formatBoolAsPostgresSetting(evalCtx.SessionData().DisableHoistProjectionInJoinLimitation), nil
+		},
+		GlobalDefault: globalFalse,
+	},
 }
 
 const compatErrMsg = "this parameter is currently recognized only for compatibility and has no effect in CockroachDB."