rules: suppress a dep-rule in special case

pkg/sql/schemachanger/rel/schema_rules.go

@@ -80,21 +80,26 @@ func (sc *Schema) DefNotJoin1(name string, a Var, def func(a Var) Clauses) Rule1
 	return sc.rule(name, notJoin, def, a).(Rule1)
 }
 
-// DefNotJoin2 defines a not-join rule with two bound variable arguments.
-func (sc *Schema) DefNotJoin2(name string, a, b Var, def func(a, b Var) Clauses) Rule2 {
-	return sc.rule(name, notJoin, def, a, b).(Rule2)
-}
-
 // Def2 defines a Rule2.
 func (sc *Schema) Def2(name string, a, b Var, def func(a, b Var) Clauses) Rule2 {
 	return sc.rule(name, regular, def, a, b).(Rule2)
 }
 
+// DefNotJoin2 defines a not-join rule with two bound variable arguments.
+func (sc *Schema) DefNotJoin2(name string, a, b Var, def func(a, b Var) Clauses) Rule2 {
+	return sc.rule(name, notJoin, def, a, b).(Rule2)
+}
+
 // Def3 defines a Rule3.
 func (sc *Schema) Def3(name string, a, b, c Var, def func(a, b, c Var) Clauses) Rule3 {
 	return sc.rule(name, regular, def, a, b, c).(Rule3)
 }
 
+// DefNotJoin3 defines a not-join rule with three bound variable arguments.
+func (sc *Schema) DefNotJoin3(name string, a, b, c Var, def func(a, b, c Var) Clauses) Rule3 {
+	return sc.rule(name, notJoin, def, a, b, c).(Rule3)
+}
+
 // Def4 defines a Rule4.
 func (sc *Schema) Def4(name string, a, b, c, d Var, def func(a, b, c, d Var) Clauses) Rule4 {
 	return sc.rule(name, regular, def, a, b, c, d).(Rule4)

pkg/sql/schemachanger/scplan/internal/opgen/register.go

@@ -230,10 +230,10 @@ func validateTargets(targets []target) error {
 	}
 
 	for s := range allStatuses {
-		if !absentStatuses[s] {
+		if nonAbsentStatuses[s] && !absentStatuses[s] {
 			return errors.Errorf("status %s is featured in non-ABSENT targets but not in the ABSENT target", s)
 		}
-		if !nonAbsentStatuses[s] {
+		if absentStatuses[s] && !nonAbsentStatuses[s] {
 			return errors.Errorf("status %s is featured in ABSENT target but not in any non-ABSENT targets", s)
 		}
 	}

pkg/sql/schemachanger/scplan/internal/rules/dep_drop_object.go

@@ -67,6 +67,7 @@ func init() {
 				to.typeFilter(isSimpleDependent),
 				joinOnDescID(from, to, "desc-id"),
 				statusesToAbsent(from, scpb.Status_DROPPED, to, scpb.Status_ABSENT),
+				fromHasPublicStatusIfFromIsTableAndToIsRowLevelTTL(from.target, from.el, to.el),
 			}
 		})
 

pkg/sql/schemachanger/scplan/internal/rules/helpers.go

@@ -486,3 +486,30 @@ var descriptorIsNotBeingDropped = screl.Schema.DefNotJoin1(
 		}
 	},
 )
+
+// fromHasPublicStatusIfFromIsTableAndToIsRowLevelTTL creates
+// a clause which leads to the outer clause failing to unify
+// if the passed element `from` is a Table, `to` is a RowLevelTTl,
+// and there does not exist a node with the same target as
+// `fromTarget` in PUBLIC status.
+// It is used to suppress rule "descriptor drop right before dependent element removal"
+// for the special case where we drop a rowLevelTTL table in mixed
+// version state for forward compatibility (issue #86672).
+var fromHasPublicStatusIfFromIsTableAndToIsRowLevelTTL = screl.Schema.DefNotJoin3(
+	"fromHasPublicStatusIfFromIsTableAndToIsRowLevelTTL",
+	"fromTarget", "fromEl", "toEl", func(fromTarget, fromEl, toEl rel.Var) rel.Clauses {
+		n := rel.Var("n")
+		return rel.Clauses{
+			fromEl.Type((*scpb.Table)(nil)),
+			toEl.Type((*scpb.RowLevelTTL)(nil)),
+			n.Type((*screl.Node)(nil)),
+			n.AttrEqVar(screl.Target, fromTarget),
+			screl.Schema.DefNotJoin1("nodeHasNoPublicStatus", "n", func(n rel.Var) rel.Clauses {
+				public := rel.Var("public")
+				return rel.Clauses{
+					public.Eq(scpb.Status_PUBLIC),
+					n.AttrEqVar(screl.CurrentStatus, public),
+				}
+			})(n),
+		}
+	})

pkg/sql/schemachanger/scplan/internal/rules/testdata/deprules

@@ -15,6 +15,13 @@ descriptorIsNotBeingDropped($element):
         - joinTarget($descriptor, $descriptor-target)
         - joinOnDescID($descriptor, $element, $id)
         - $descriptor-target[TargetStatus] = ABSENT
+fromHasPublicStatusIfFromIsTableAndToIsRowLevelTTL($fromTarget, $fromEl, $toEl):
+    not-join:
+        - $fromEl[Type] = '*scpb.Table'
+        - $toEl[Type] = '*scpb.RowLevelTTL'
+        - $n[Type] = '*screl.Node'
+        - $n[Target] = $fromTarget
+        - nodeHasNoPublicStatus($n)
 joinOnColumnID($a, $b, $desc-id, $col-id):
     - joinOnDescID($a, $b, $desc-id)
     - $a[ColumnID] = $col-id
@@ -41,6 +48,10 @@ joinTargetNode($element, $target, $node):
     - joinTarget($element, $target)
     - $node[Type] = '*screl.Node'
     - $node[Target] = $target
+nodeHasNoPublicStatus($n):
+    not-join:
+        - $public = PUBLIC
+        - $n[CurrentStatus] = $public
 nodeNotExistsWithStatusIn_BACKFILLED_BACKFILL_ONLY($sharedTarget):
     not-join:
         - $n[Type] = '*screl.Node'
@@ -1664,6 +1675,7 @@ deprules
     - toAbsent($descriptor-target, $dependent-target)
     - $descriptor-node[CurrentStatus] = DROPPED
     - $dependent-node[CurrentStatus] = ABSENT
+    - fromHasPublicStatusIfFromIsTableAndToIsRowLevelTTL($descriptor-target, $descriptor, $dependent)
     - joinTargetNode($descriptor, $descriptor-target, $descriptor-node)
     - joinTargetNode($dependent, $dependent-target, $dependent-node)
 - name: descriptor drop right before removing dependent with attr ref

pkg/sql/schemachanger/scplan/internal/rules/testdata/oprules

@@ -15,6 +15,13 @@ descriptorIsNotBeingDropped($element):
         - joinTarget($descriptor, $descriptor-target)
         - joinOnDescID($descriptor, $element, $id)
         - $descriptor-target[TargetStatus] = ABSENT
+fromHasPublicStatusIfFromIsTableAndToIsRowLevelTTL($fromTarget, $fromEl, $toEl):
+    not-join:
+        - $fromEl[Type] = '*scpb.Table'
+        - $toEl[Type] = '*scpb.RowLevelTTL'
+        - $n[Type] = '*screl.Node'
+        - $n[Target] = $fromTarget
+        - nodeHasNoPublicStatus($n)
 joinOnColumnID($a, $b, $desc-id, $col-id):
     - joinOnDescID($a, $b, $desc-id)
     - $a[ColumnID] = $col-id
@@ -41,6 +48,10 @@ joinTargetNode($element, $target, $node):
     - joinTarget($element, $target)
     - $node[Type] = '*screl.Node'
     - $node[Target] = $target
+nodeHasNoPublicStatus($n):
+    not-join:
+        - $public = PUBLIC
+        - $n[CurrentStatus] = $public
 nodeNotExistsWithStatusIn_BACKFILLED_BACKFILL_ONLY($sharedTarget):
     not-join:
         - $n[Type] = '*screl.Node'

pkg/sql/schemachanger/scplan/internal/scgraph/graph.go

@@ -23,7 +23,7 @@ import (
 	"github.com/cockroachdb/redact"
 )
 
-// Graph is a graph whose nodes are *scpb.Nodes. Graphs are constructed during
+// Graph is a graph whose nodes are *screl.Nodes. Graphs are constructed during
 // schema change planning. Edges in the graph represent dependencies between
 // nodes, either due to the sequencing of statuses for a single target or due to
 // inter-target dependencies between statuses.