scplan: Fix deprules for dropping computed columns

This PR fixes the new schema changer deprules for dropping virtual computed columns which are also used for hash and expression indexes. Currently, the optimizer allows for virtual, computed columns to be evaluated even when under mutation. However, this causes concurrent DML issues when the schemachanger job is running as the column that the virtual computed column depends on moves into WRITE_ONLY stage prior to the computed column being dropped. As a result, the optimizer is unable to access the column for evaluating the compute expression. This PR updates the dep rules to ensure the virtual, computed column is dropped before the dependent column moves to WRITE_ONLY ensuring that the compute expression can be enforced correctly for concurrent DML during all stages of the schema change. Epic: none Fixes: cockroachdb#111608 Fixes: cockroachdb#111619 Release note: None
rimadeodhar · Mar 20, 2024 · 28d9cb7 · 28d9cb7
1 parent 726a650
commit 28d9cb7
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Showing 19 changed files with 1,168 additions and 1,080 deletions.
diff --git a/pkg/sql/schemachanger/dml_injection_test.go b/pkg/sql/schemachanger/dml_injection_test.go
@@ -345,7 +345,6 @@ func TestAlterTableDMLInjection(t *testing.T) {
 				"CREATE INDEX idx ON tbl (i) USING HASH",
 			},
 			schemaChange: "ALTER TABLE tbl DROP COLUMN i CASCADE",
-			skipIssue:    111619,
 		},
 		{
 			desc: "drop column with composite index + fk",
@@ -407,7 +406,6 @@ func TestAlterTableDMLInjection(t *testing.T) {
 				"CREATE INDEX idx ON tbl ((i + 1))",
 			},
 			schemaChange: "ALTER TABLE tbl DROP COLUMN i CASCADE",
-			skipIssue:    111608,
 		},
 		{
 			desc:         "create materialized view from index",

diff --git a/pkg/sql/schemachanger/scplan/internal/rules/current/dep_drop_column.go b/pkg/sql/schemachanger/scplan/internal/rules/current/dep_drop_column.go
@@ -113,6 +113,51 @@ func init() {
 		},
 	)
 
+	// This rule ensures that a column is dropped only after any virtual, computed column dependent
+	// on the column is dropped i.e. if B is a virtual, computed column using column A
+	// in its compute expression, this rule ensures that the compute expression of B is dropped before
+	// A is dropped. The rules above ensure that the column B is dropped before the expression is dropped
+	// so this rule also implicitly implies that column B is dropped before column A.
+	// This is relevant for expression and hash indexes which create an internal, virtual column
+	// which computes the hash/expression key for the index.
+	//
+	// N.B. This rules has been intentionally made very specific to only virtual, computed columns as opposed
+	// to all computed columns. This is due an edge case within the optimizer which actually allows
+	// the compute expressions of virtual computed columns to be evaluated during an active schema change.
+	// Without this rule, the optimizer is unable to read the dependent column as the dependent column
+	// moves to the WRITE_ONLY stage before the computed column is fully dropped. As of now, we don't
+	// need to apply to all computed columns as the optimizer doesn't evaluate their expressions while
+	// dropping them so the above rule where the column type is dropped before the column is sufficient
+	// to enforce the dependency.
+	registerDepRuleForDrop(
+		"Virtual computed column expression is dropped before the column it depends on",
+		scgraph.Precedence,
+		"virtual-column-expr", "column",
+		scpb.Status_ABSENT, scpb.Status_WRITE_ONLY,
+		func(from, to NodeVars) rel.Clauses {
+			return rel.Clauses{
+				from.Type((*scpb.ColumnType)(nil)),
+				to.Type((*scpb.Column)(nil)),
+				JoinOnDescID(from, to, "table-id"),
+				FilterElements("computedColumnTypeReferencesColumn", from, to,
+					func(colType *scpb.ColumnType, column *scpb.Column) bool {
+						if !colType.IsVirtual {
+							return false
+						}
+						if colType.ComputeExpr == nil {
+							return false
+						}
+						for _, refColumns := range colType.ComputeExpr.ReferencedColumnIDs {
+							if refColumns == column.ColumnID {
+								return true
+							}
+						}
+						return false
+					}),
+			}
+		},
+	)
+
 	// Column constraint disappears in the same stage as the column
 	// becomes WRITE_ONLY.
 	//
@@ -138,6 +183,31 @@ func init() {
 			}
 		},
 	)
+
+	// This rule enforces that a new primary index moves to the public stage only after all columns stored
+	// within the old primary index move to WRITE_ONLY. Without this, the new primary index is at risk of not
+	// storing all public columns within the table (as the column being dropped is still considered public
+	// before it moves to WRITE_ONLY but the new primary index does not contain it since the schema changer
+	// knows it is transitioning to a target status of ABSENT).
+	registerDepRule(
+		"New primary index should go public only after columns being dropped move to WRITE_ONLY",
+		scgraph.Precedence,
+		"column", "new-primary-index",
+		func(from, to NodeVars) rel.Clauses {
+			ic := MkNodeVars("index-column")
+			relationID, columnID, indexID := rel.Var("table-id"), rel.Var("column-id"), rel.Var("index-id")
+			return rel.Clauses{
+				from.Type((*scpb.Column)(nil)),
+				to.Type((*scpb.PrimaryIndex)(nil)),
+				ColumnInSourcePrimaryIndex(ic, to, relationID, columnID, indexID),
+				JoinOnColumnID(ic, from, relationID, columnID),
+				from.TargetStatus(scpb.ToAbsent),
+				from.CurrentStatus(scpb.Status_WRITE_ONLY),
+				to.TargetStatus(scpb.ToPublic),
+				to.CurrentStatus(scpb.Status_PUBLIC),
+			}
+		},
+	)
 }
 
 // Special rules partial predicate expressions, which ensure that any columns
@@ -170,6 +240,7 @@ func init() {
 			}
 		},
 	)
+
 	registerDepRuleForDrop(
 		"secondary index partial no longer public before referenced column",
 		scgraph.Precedence,

diff --git a/pkg/sql/schemachanger/scplan/internal/rules/current/testdata/deprules b/pkg/sql/schemachanger/scplan/internal/rules/current/testdata/deprules
@@ -628,6 +628,21 @@ deprules
     - descriptorIsDataNotBeingAdded-24.1($descID)
     - joinTargetNode($prev, $prev-Target, $prev-Node)
     - joinTargetNode($next, $next-Target, $next-Node)
+- name: New primary index should go public only after columns being dropped move to WRITE_ONLY
+  from: column-Node
+  kind: Precedence
+  to: new-primary-index-Node
+  query:
+    - $column[Type] = '*scpb.Column'
+    - $new-primary-index[Type] = '*scpb.PrimaryIndex'
+    - ColumnInSourcePrimaryIndex($index-column, $new-primary-index, $table-id, $column-id, $index-id)
+    - joinOnColumnID($index-column, $column, $table-id, $column-id)
+    - $column-Target[TargetStatus] = ABSENT
+    - $column-Node[CurrentStatus] = WRITE_ONLY
+    - $new-primary-index-Target[TargetStatus] = PUBLIC
+    - $new-primary-index-Node[CurrentStatus] = PUBLIC
+    - joinTargetNode($column, $column-Target, $column-Node)
+    - joinTargetNode($new-primary-index, $new-primary-index-Target, $new-primary-index-Node)
 - name: 'PrimaryIndex transitions to ABSENT uphold 2-version invariant: BACKFILLED->DELETE_ONLY'
   from: prev-Node
   kind: PreviousTransactionPrecedence
@@ -2107,6 +2122,64 @@ deprules
     - descriptorIsDataNotBeingAdded-24.1($descID)
     - joinTargetNode($prev, $prev-Target, $prev-Node)
     - joinTargetNode($next, $next-Target, $next-Node)
+- name: Virtual computed column expression is dropped before the column it depends on
+  from: virtual-column-expr-Node
+  kind: Precedence
+  to: column-Node
+  query:
+    - $virtual-column-expr[Type] = '*scpb.ColumnType'
+    - $column[Type] = '*scpb.Column'
+    - joinOnDescID($virtual-column-expr, $column, $table-id)
+    - computedColumnTypeReferencesColumn(*scpb.ColumnType, *scpb.Column)($virtual-column-expr, $column)
+    - toAbsent($virtual-column-expr-Target, $column-Target)
+    - $virtual-column-expr-Node[CurrentStatus] = ABSENT
+    - $column-Node[CurrentStatus] = WRITE_ONLY
+    - joinTargetNode($virtual-column-expr, $virtual-column-expr-Target, $virtual-column-expr-Node)
+    - joinTargetNode($column, $column-Target, $column-Node)
+- name: Virtual computed column expression is dropped before the column it depends on
+  from: virtual-column-expr-Node
+  kind: Precedence
+  to: column-Node
+  query:
+    - $virtual-column-expr[Type] = '*scpb.ColumnType'
+    - $column[Type] = '*scpb.Column'
+    - joinOnDescID($virtual-column-expr, $column, $table-id)
+    - computedColumnTypeReferencesColumn(*scpb.ColumnType, *scpb.Column)($virtual-column-expr, $column)
+    - transient($virtual-column-expr-Target, $column-Target)
+    - $virtual-column-expr-Node[CurrentStatus] = TRANSIENT_ABSENT
+    - $column-Node[CurrentStatus] = TRANSIENT_WRITE_ONLY
+    - joinTargetNode($virtual-column-expr, $virtual-column-expr-Target, $virtual-column-expr-Node)
+    - joinTargetNode($column, $column-Target, $column-Node)
+- name: Virtual computed column expression is dropped before the column it depends on
+  from: virtual-column-expr-Node
+  kind: Precedence
+  to: column-Node
+  query:
+    - $virtual-column-expr[Type] = '*scpb.ColumnType'
+    - $column[Type] = '*scpb.Column'
+    - joinOnDescID($virtual-column-expr, $column, $table-id)
+    - computedColumnTypeReferencesColumn(*scpb.ColumnType, *scpb.Column)($virtual-column-expr, $column)
+    - $virtual-column-expr-Target[TargetStatus] = TRANSIENT_ABSENT
+    - $virtual-column-expr-Node[CurrentStatus] = TRANSIENT_ABSENT
+    - $column-Target[TargetStatus] = ABSENT
+    - $column-Node[CurrentStatus] = WRITE_ONLY
+    - joinTargetNode($virtual-column-expr, $virtual-column-expr-Target, $virtual-column-expr-Node)
+    - joinTargetNode($column, $column-Target, $column-Node)
+- name: Virtual computed column expression is dropped before the column it depends on
+  from: virtual-column-expr-Node
+  kind: Precedence
+  to: column-Node
+  query:
+    - $virtual-column-expr[Type] = '*scpb.ColumnType'
+    - $column[Type] = '*scpb.Column'
+    - joinOnDescID($virtual-column-expr, $column, $table-id)
+    - computedColumnTypeReferencesColumn(*scpb.ColumnType, *scpb.Column)($virtual-column-expr, $column)
+    - $virtual-column-expr-Target[TargetStatus] = ABSENT
+    - $virtual-column-expr-Node[CurrentStatus] = ABSENT
+    - $column-Target[TargetStatus] = TRANSIENT_ABSENT
+    - $column-Node[CurrentStatus] = TRANSIENT_WRITE_ONLY
+    - joinTargetNode($virtual-column-expr, $virtual-column-expr-Target, $virtual-column-expr-Node)
+    - joinTargetNode($column, $column-Target, $column-Node)
 - name: all adding indexes reached BACKFILL_ONLY before any of their columns disappear
   from: index-Node
   kind: Precedence
@@ -4711,6 +4784,21 @@ deprules
     - descriptorIsDataNotBeingAdded-24.1($descID)
     - joinTargetNode($prev, $prev-Target, $prev-Node)
     - joinTargetNode($next, $next-Target, $next-Node)
+- name: New primary index should go public only after columns being dropped move to WRITE_ONLY
+  from: column-Node
+  kind: Precedence
+  to: new-primary-index-Node
+  query:
+    - $column[Type] = '*scpb.Column'
+    - $new-primary-index[Type] = '*scpb.PrimaryIndex'
+    - ColumnInSourcePrimaryIndex($index-column, $new-primary-index, $table-id, $column-id, $index-id)
+    - joinOnColumnID($index-column, $column, $table-id, $column-id)
+    - $column-Target[TargetStatus] = ABSENT
+    - $column-Node[CurrentStatus] = WRITE_ONLY
+    - $new-primary-index-Target[TargetStatus] = PUBLIC
+    - $new-primary-index-Node[CurrentStatus] = PUBLIC
+    - joinTargetNode($column, $column-Target, $column-Node)
+    - joinTargetNode($new-primary-index, $new-primary-index-Target, $new-primary-index-Node)
 - name: 'PrimaryIndex transitions to ABSENT uphold 2-version invariant: BACKFILLED->DELETE_ONLY'
   from: prev-Node
   kind: PreviousTransactionPrecedence
@@ -6190,6 +6278,64 @@ deprules
     - descriptorIsDataNotBeingAdded-24.1($descID)
     - joinTargetNode($prev, $prev-Target, $prev-Node)
     - joinTargetNode($next, $next-Target, $next-Node)
+- name: Virtual computed column expression is dropped before the column it depends on
+  from: virtual-column-expr-Node
+  kind: Precedence
+  to: column-Node
+  query:
+    - $virtual-column-expr[Type] = '*scpb.ColumnType'
+    - $column[Type] = '*scpb.Column'
+    - joinOnDescID($virtual-column-expr, $column, $table-id)
+    - computedColumnTypeReferencesColumn(*scpb.ColumnType, *scpb.Column)($virtual-column-expr, $column)
+    - toAbsent($virtual-column-expr-Target, $column-Target)
+    - $virtual-column-expr-Node[CurrentStatus] = ABSENT
+    - $column-Node[CurrentStatus] = WRITE_ONLY
+    - joinTargetNode($virtual-column-expr, $virtual-column-expr-Target, $virtual-column-expr-Node)
+    - joinTargetNode($column, $column-Target, $column-Node)
+- name: Virtual computed column expression is dropped before the column it depends on
+  from: virtual-column-expr-Node
+  kind: Precedence
+  to: column-Node
+  query:
+    - $virtual-column-expr[Type] = '*scpb.ColumnType'
+    - $column[Type] = '*scpb.Column'
+    - joinOnDescID($virtual-column-expr, $column, $table-id)
+    - computedColumnTypeReferencesColumn(*scpb.ColumnType, *scpb.Column)($virtual-column-expr, $column)
+    - transient($virtual-column-expr-Target, $column-Target)
+    - $virtual-column-expr-Node[CurrentStatus] = TRANSIENT_ABSENT
+    - $column-Node[CurrentStatus] = TRANSIENT_WRITE_ONLY
+    - joinTargetNode($virtual-column-expr, $virtual-column-expr-Target, $virtual-column-expr-Node)
+    - joinTargetNode($column, $column-Target, $column-Node)
+- name: Virtual computed column expression is dropped before the column it depends on
+  from: virtual-column-expr-Node
+  kind: Precedence
+  to: column-Node
+  query:
+    - $virtual-column-expr[Type] = '*scpb.ColumnType'
+    - $column[Type] = '*scpb.Column'
+    - joinOnDescID($virtual-column-expr, $column, $table-id)
+    - computedColumnTypeReferencesColumn(*scpb.ColumnType, *scpb.Column)($virtual-column-expr, $column)
+    - $virtual-column-expr-Target[TargetStatus] = TRANSIENT_ABSENT
+    - $virtual-column-expr-Node[CurrentStatus] = TRANSIENT_ABSENT
+    - $column-Target[TargetStatus] = ABSENT
+    - $column-Node[CurrentStatus] = WRITE_ONLY
+    - joinTargetNode($virtual-column-expr, $virtual-column-expr-Target, $virtual-column-expr-Node)
+    - joinTargetNode($column, $column-Target, $column-Node)
+- name: Virtual computed column expression is dropped before the column it depends on
+  from: virtual-column-expr-Node
+  kind: Precedence
+  to: column-Node
+  query:
+    - $virtual-column-expr[Type] = '*scpb.ColumnType'
+    - $column[Type] = '*scpb.Column'
+    - joinOnDescID($virtual-column-expr, $column, $table-id)
+    - computedColumnTypeReferencesColumn(*scpb.ColumnType, *scpb.Column)($virtual-column-expr, $column)
+    - $virtual-column-expr-Target[TargetStatus] = ABSENT
+    - $virtual-column-expr-Node[CurrentStatus] = ABSENT
+    - $column-Target[TargetStatus] = TRANSIENT_ABSENT
+    - $column-Node[CurrentStatus] = TRANSIENT_WRITE_ONLY
+    - joinTargetNode($virtual-column-expr, $virtual-column-expr-Target, $virtual-column-expr-Node)
+    - joinTargetNode($column, $column-Target, $column-Node)
 - name: all adding indexes reached BACKFILL_ONLY before any of their columns disappear
   from: index-Node
   kind: Precedence

diff --git a/pkg/sql/schemachanger/scplan/internal/rules/helpers.go b/pkg/sql/schemachanger/scplan/internal/rules/helpers.go
@@ -140,6 +140,11 @@ func ColumnInSwappedInPrimaryIndex(
 	return columnInSwappedInPrimaryIndexUntyped(indexColumn.El, index.El, relationIDVar, columnIDVar, indexIDVar)
 }
 
+func ColumnInSourcePrimaryIndex(indexColumn, index NodeVars, relationIDVar, columnIDVar, indexIDVar rel.Var,
+) rel.Clause {
+	return columnInSourcePrimaryIndex(indexColumn.El, index.El, relationIDVar, columnIDVar, indexIDVar)
+}
+
 // IsPotentialSecondaryIndexSwap determines if a secondary index recreate is
 // occurring because of a primary key alter.
 func IsPotentialSecondaryIndexSwap(indexIdVar rel.Var, tableIDVar rel.Var) rel.Clauses {
@@ -292,6 +297,21 @@ var (
 			}
 		})
 
+	columnInSourcePrimaryIndex = screl.Schema.Def5(
+		"ColumnInSourcePrimaryIndex",
+		"index-column", "index", "table-id", "column-id", "index-id", func(
+			indexColumn, index, tableID, columnID, indexID rel.Var,
+		) rel.Clauses {
+			return rel.Clauses{
+				indexColumn.Type((*scpb.IndexColumn)(nil)),
+				indexColumn.AttrEqVar(screl.DescID, rel.Blank),
+				indexColumn.AttrEqVar(screl.ColumnID, columnID),
+				indexColumn.AttrEqVar(screl.IndexID, indexID),
+				index.AttrEqVar(screl.SourceIndexID, indexID),
+				JoinOnDescIDUntyped(index, indexColumn, tableID),
+			}
+		})
+
 	// IsNotPotentialSecondaryIndexSwap determines if no secondary index recreation
 	// is happening because of a primary key alter.
 	IsNotPotentialSecondaryIndexSwap = screl.Schema.DefNotJoin2("no secondary index swap is on going",

diff --git a/pkg/sql/schemachanger/scplan/testdata/alter_table_alter_primary_key b/pkg/sql/schemachanger/scplan/testdata/alter_table_alter_primary_key
@@ -635,6 +635,10 @@ ALTER TABLE t ALTER PRIMARY KEY USING COLUMNS (k);
   to:   [IndexColumn:{DescID: 104, ColumnID: 3, IndexID: 3}, TRANSIENT_ABSENT]
   kind: Precedence
   rule: column no longer public before dependents
+- from: [Column:{DescID: 104, ColumnID: 3}, WRITE_ONLY]
+  to:   [PrimaryIndex:{DescID: 104, IndexID: 4, ConstraintID: 4, TemporaryIndexID: 5, SourceIndexID: 2}, PUBLIC]
+  kind: Precedence
+  rule: New primary index should go public only after columns being dropped move to WRITE_ONLY
 - from: [ColumnDefaultExpression:{DescID: 104, ColumnID: 3, Expr: unique_rowid()}, ABSENT]
   to:   [Column:{DescID: 104, ColumnID: 3}, ABSENT]
   kind: Precedence

diff --git a/pkg/sql/schemachanger/scplan/testdata/alter_table_drop_column b/pkg/sql/schemachanger/scplan/testdata/alter_table_drop_column
@@ -788,6 +788,10 @@ ALTER TABLE defaultdb.foo DROP COLUMN v1 CASCADE;
   to:   [IndexColumn:{DescID: 107, ColumnID: 2, IndexID: 2}, ABSENT]
   kind: Precedence
   rule: column no longer public before dependents
+- from: [Column:{DescID: 107, ColumnID: 2}, WRITE_ONLY]
+  to:   [PrimaryIndex:{DescID: 107, IndexID: 3, ConstraintID: 3, TemporaryIndexID: 4, SourceIndexID: 1}, PUBLIC]
+  kind: Precedence
+  rule: New primary index should go public only after columns being dropped move to WRITE_ONLY
 - from: [Column:{DescID: 108, ColumnID: 1}, ABSENT]
   to:   [View:{DescID: 108}, ABSENT]
   kind: Precedence
@@ -2146,6 +2150,10 @@ ALTER TABLE defaultdb.foo DROP COLUMN v2 CASCADE;
   to:   [IndexColumn:{DescID: 107, ColumnID: 3, IndexID: 2}, ABSENT]
   kind: Precedence
   rule: column no longer public before dependents
+- from: [Column:{DescID: 107, ColumnID: 3}, WRITE_ONLY]
+  to:   [PrimaryIndex:{DescID: 107, IndexID: 3, ConstraintID: 3, TemporaryIndexID: 4, SourceIndexID: 1}, PUBLIC]
+  kind: Precedence
+  rule: New primary index should go public only after columns being dropped move to WRITE_ONLY
 - from: [Column:{DescID: 108, ColumnID: 1}, ABSENT]
   to:   [View:{DescID: 108}, ABSENT]
   kind: Precedence
@@ -3157,6 +3165,10 @@ ALTER TABLE defaultdb.foo DROP COLUMN udfcol;
   to:   [IndexColumn:{DescID: 107, ColumnID: 4, IndexID: 1}, ABSENT]
   kind: Precedence
   rule: column no longer public before dependents
+- from: [Column:{DescID: 107, ColumnID: 4}, WRITE_ONLY]
+  to:   [PrimaryIndex:{DescID: 107, IndexID: 3, ConstraintID: 3, TemporaryIndexID: 4, SourceIndexID: 1}, PUBLIC]
+  kind: Precedence
+  rule: New primary index should go public only after columns being dropped move to WRITE_ONLY
 - from: [ColumnDefaultExpression:{DescID: 107, ColumnID: 4, Expr: [FUNCTION 100109](), ReferencedFunctionIDs: [109]}, ABSENT]
   to:   [Column:{DescID: 107, ColumnID: 4}, ABSENT]
   kind: Precedence