Merge pull request #81364 from rytaft/backport21.2-81331

release-21.2: opt: do not use placeholder fast path if types do not match

pkg/sql/logictest/testdata/logic_test/prepare

@@ -1390,3 +1390,30 @@ PREPARE q64765 as SELECT * FROM t64765 WHERE x = $1 AND y = $2
 
 statement ok
 EXECUTE q64765(1, 1)
+
+# Regression test for #81315.
+statement ok
+CREATE TABLE t81315 (a DECIMAL NOT NULL PRIMARY KEY, b INT);
+PREPARE q81315 AS SELECT * FROM t81315 WHERE a = $1::INT8;
+INSERT INTO t81315 VALUES (1, 100), (2, 200)
+
+query TI
+SELECT * FROM t81315 WHERE a = 1
+----
+1  100
+
+query TI
+EXECUTE q81315 (1)
+----
+1  100
+
+statement ok
+CREATE TABLE t81315_2 (
+  k INT PRIMARY KEY,
+  a INT
+);
+PREPARE q81315_2 AS SELECT * FROM t81315_2 WHERE k = $1;
+INSERT INTO t81315_2 VALUES (1, 1)
+
+statement error expected EXECUTE parameter expression to have type int
+EXECUTE q81315_2(1::DECIMAL)

pkg/sql/opt/xform/placeholder_fast_path.go

@@ -15,6 +15,7 @@ import (
 	"github.com/cockroachdb/cockroach/pkg/sql/opt/cat"
 	"github.com/cockroachdb/cockroach/pkg/sql/opt/memo"
 	"github.com/cockroachdb/cockroach/pkg/sql/opt/props/physical"
+	"github.com/cockroachdb/cockroach/pkg/sql/types"
 	"github.com/cockroachdb/cockroach/pkg/util"
 	"github.com/cockroachdb/cockroach/pkg/util/errorutil"
 	"github.com/cockroachdb/errors"
@@ -198,6 +199,9 @@ func (o *Optimizer) TryPlaceholderFastPath() (_ opt.Expr, ok bool, err error) {
 		for j := range sel.Filters {
 			eq := sel.Filters[j].Condition.(*memo.EqExpr)
 			if v := eq.Left.(*memo.VariableExpr); v.Col == col {
+				if !verifyType(o.mem.Metadata(), col, eq.Right.DataType()) {
+					return nil, false, nil
+				}
 				span[i] = eq.Right
 				break
 			}
@@ -221,3 +225,12 @@ func (o *Optimizer) TryPlaceholderFastPath() (_ opt.Expr, ok bool, err error) {
 
 	return placeholderScan, true, nil
 }
+
+// verifyType checks that the type of the index column col matches the
+// given type. We disallow mixed-type comparisons because it would result in
+// incorrect encodings (See #4313 and #81315).
+// TODO(rytaft): We may be able to use the placeholder fast path for
+// this case if we add logic similar to UnifyComparisonTypes.
+func verifyType(md *opt.Metadata, col opt.ColumnID, typ *types.T) bool {
+	return typ.Family() == types.UnknownFamily || md.ColumnMeta(col).Type.Equivalent(typ)
+}

pkg/sql/opt/xform/testdata/placeholder-fast-path/scan

@@ -300,3 +300,29 @@ placeholder-fast-path
 SELECT * FROM xyz WHERE x = $1 AND y = $2
 ----
 no fast path
+
+# Regression test for #81315. Do not use the placeholder fast path
+# if the types do not match.
+exec-ddl
+CREATE TABLE t_dec (a DECIMAL NOT NULL PRIMARY KEY, b INT);
+----
+
+# TODO(rytaft): We may be able to use the placeholder fast path for
+# this case if we add logic similar to UnifyComparisonTypes.
+placeholder-fast-path
+SELECT * FROM t_dec WHERE a = $1::INT8;
+----
+no fast path
+
+placeholder-fast-path
+SELECT * FROM t_dec WHERE a = $1;
+----
+placeholder-scan t_dec
+ ├── columns: a:1!null b:2
+ ├── cardinality: [0 - 1]
+ ├── immutable, has-placeholder
+ ├── stats: [rows=1, distinct(1)=1, null(1)=0]
+ ├── key: ()
+ ├── fd: ()-->(1,2)
+ └── span
+      └── $1