norm: early inlining of WITH bound expression with VALUES

Fixes https://github.com/cockroachlabs/support/issues/1769

This commit implements early inlining of WITH clause bound expressions
(at the time when the WithScanExpr is normalized) if the
WITH bound expression is a ValuesExpr with all constant expressions or
placeholders and it appears in an IN or NOT IN expression, for example:
`column IN (VALUES(...))` or `column NOT IN(VALUES(...))`.
Not doing early inlining can result in a superfluous join.

Normally WITH clause inlining is done when the top-level WithExpr is
normalized, but since normalization is done bottom-up, the WithExpr is
processed last, making the inlining too late to trigger other
normalization rules.

Release note (performance improvement): This patch adds early inlining
of VALUES clauses and unnested arrays in WITH queries in order to
eliminate unnecessary joins.

pkg/sql/logictest/testdata/logic_test/apply_join

@@ -529,7 +529,7 @@ FROM
 
 query error pq: st_mpointfromwkb\(\): error parsing EWKB: wkb: unknown byte order: 11000000
 WITH
-  with_111870 (col_664924) AS (SELECT * FROM (VALUES (NULL)) AS tab_397795 (col_664924))
+  with_111870 (col_664924) AS (SELECT * FROM (VALUES (true)) AS tab_397795 (col_664924))
 SELECT
   cte_ref_33032.col_664924 AS col_664951
 FROM

pkg/sql/opt/memo/expr.go

@@ -1281,3 +1281,54 @@ func (g *GroupingPrivate) GroupingOrderType(required *props.OrderingChoice) Grou
 	}
 	return PartialStreaming
 }
+
+// IsConstantsAndPlaceholders returns true if all values in the list are
+// constant, placeholders or tuples containing constants, placeholders or other
+// such nested tuples.
+func (v *ValuesExpr) IsConstantsAndPlaceholders() bool {
+	// Constant expressions should be leak-proof, so this is a quick test to
+	// determine if the ValuesExpr even needs to be checked.
+	if !v.Relational().VolatilitySet.IsLeakproof() {
+		return false
+	}
+	// Another quick check for something other than constants
+	if !v.Relational().OuterCols.Empty() {
+		return false
+	}
+	// A safety check
+	if len(v.Rows) == 0 {
+		return false
+	}
+	if !v.Rows.IsConstantsAndPlaceholders(v.Memo().EvalContext()) {
+		return false
+	}
+	return true
+}
+
+// IsConstantsAndPlaceholders returns true if all scalar expressions in the list
+// are constants, placeholders or tuples containing constants or placeholders.
+// If a tuple nested within a tuple is found, false is returned.
+func (e ScalarListExpr) IsConstantsAndPlaceholders(evalCtx *eval.Context) bool {
+	return e.isConstantsAndPlaceholders(evalCtx, false /* insideTuple */)
+}
+
+func (e ScalarListExpr) isConstantsAndPlaceholders(evalCtx *eval.Context, insideTuple bool) bool {
+	for _, scalarExpr := range e {
+		if tupleExpr, ok := scalarExpr.(*TupleExpr); ok {
+			if insideTuple {
+				return false
+			}
+			if !tupleExpr.Elems.isConstantsAndPlaceholders(evalCtx, true) {
+				return false
+			}
+		} else {
+			if scalarExpr == nil {
+				panic(errors.AssertionFailedf("nil scalar expression in list"))
+			}
+			if !opt.IsConstValueOp(scalarExpr) && scalarExpr.Op() != opt.PlaceholderOp {
+				return false
+			}
+		}
+	}
+	return true
+}

pkg/sql/opt/norm/rules/scalar.opt

@@ -70,6 +70,20 @@ $item
 =>
 $input
 
+# InlineAnyWithScan matches on an ANY or NOT ANY expression which was generated
+# from expressions like `column IN (WithScan)` or `column NOT IN (WithScan)`,
+# where the WITH clause definition was normalized into a VALUES clause with
+# constants or placeholders. The `WithScan` is replaced with the VALUES clause
+# in order to avoid a join and can potentially enable a constrained index scan.
+[InlineAnyWithScan, Normalize]
+(Any
+    (WithScan $withScanPrivate:*)
+    $scalar:* & (CanInlineWithScan $withScanPrivate $scalar)
+    $anyPrivate:*
+)
+=>
+(Any (InlineWithScan $withScanPrivate) $scalar $anyPrivate)
+
 # NormalizeInConst ensures that the In operator's tuple operand is sorted with
 # duplicates removed (since duplicates do not change the result).
 [NormalizeInConst, Normalize]

pkg/sql/opt/norm/testdata/rules/with

@@ -173,7 +173,6 @@ with &2 (bar)
                           ├── key: ()
                           └── fd: ()-->(5)
 
-# We should inline foo, but not bar.
 norm expect=InlineWith
 WITH foo AS (SELECT 1), bar AS (SELECT 2) SELECT * FROM foo CROSS JOIN bar CROSS JOIN bar AS bar2
 ----
@@ -876,3 +875,180 @@ scalar-group-by
  └── aggregations
       └── sum [as=sum:6, outer=(5)]
            └── n:5
+
+# --------------------------------------------------
+# InlineAnyWithScan
+# --------------------------------------------------
+
+exec-ddl
+CREATE TABLE t87790(i INT, j INT, k float, CONSTRAINT "primary" PRIMARY KEY (i,j))
+----
+
+# An array unnested to VALUES should be inlined.
+norm expect=InlineAnyWithScan
+WITH ivals AS (SELECT * FROM unnest(ARRAY[1,2,3]))
+SELECT * FROM t87790 WHERE i IN (SELECT * FROM ivals)
+----
+select
+ ├── columns: i:2!null j:3!null k:4
+ ├── key: (2,3)
+ ├── fd: (2,3)-->(4)
+ ├── scan t87790
+ │    ├── columns: i:2!null j:3!null k:4
+ │    ├── key: (2,3)
+ │    └── fd: (2,3)-->(4)
+ └── filters
+      └── i:2 IN (1, 2, 3) [outer=(2), constraints=(/2: [/1 - /1] [/2 - /2] [/3 - /3]; tight)]
+
+# An array unnested to VALUES in a MATERIALIZED WITH should not be inlined.
+norm expect-not=InlineAnyWithScan
+WITH ivals AS MATERIALIZED (SELECT * FROM unnest(ARRAY[1,2,3]))
+SELECT * FROM t87790 WHERE i IN (SELECT * FROM ivals)
+----
+with &1 (ivals)
+ ├── columns: i:2!null j:3!null k:4
+ ├── materialized
+ ├── key: (2,3)
+ ├── fd: (2,3)-->(4)
+ ├── values
+ │    ├── columns: unnest:1!null
+ │    ├── cardinality: [3 - 3]
+ │    ├── (1,)
+ │    ├── (2,)
+ │    └── (3,)
+ └── semi-join (hash)
+      ├── columns: i:2!null j:3!null k:4
+      ├── key: (2,3)
+      ├── fd: (2,3)-->(4)
+      ├── scan t87790
+      │    ├── columns: i:2!null j:3!null k:4
+      │    ├── key: (2,3)
+      │    └── fd: (2,3)-->(4)
+      ├── with-scan &1 (ivals)
+      │    ├── columns: unnest:7!null
+      │    ├── mapping:
+      │    │    └──  unnest:1 => unnest:7
+      │    └── cardinality: [3 - 3]
+      └── filters
+           └── i:2 = unnest:7 [outer=(2,7), constraints=(/2: (/NULL - ]; /7: (/NULL - ]), fd=(2)==(7), (7)==(2)]
+
+# Random (volatile) VALUES should not be inlined.
+norm expect-not=InlineAnyWithScan
+WITH randvals AS (SELECT random())
+SELECT * FROM t87790 WHERE k NOT IN (SELECT * FROM randvals)
+----
+with &1 (randvals)
+ ├── columns: i:2!null j:3!null k:4
+ ├── volatile
+ ├── key: (2,3)
+ ├── fd: (2,3)-->(4)
+ ├── values
+ │    ├── columns: random:1
+ │    ├── cardinality: [1 - 1]
+ │    ├── volatile
+ │    ├── key: ()
+ │    ├── fd: ()-->(1)
+ │    └── (random(),)
+ └── anti-join (cross)
+      ├── columns: i:2!null j:3!null k:4
+      ├── key: (2,3)
+      ├── fd: (2,3)-->(4)
+      ├── scan t87790
+      │    ├── columns: i:2!null j:3!null k:4
+      │    ├── key: (2,3)
+      │    └── fd: (2,3)-->(4)
+      ├── with-scan &1 (randvals)
+      │    ├── columns: random:7
+      │    ├── mapping:
+      │    │    └──  random:1 => random:7
+      │    ├── cardinality: [1 - 1]
+      │    ├── key: ()
+      │    └── fd: ()-->(7)
+      └── filters
+           └── (k:4 = random:7) IS NOT false [outer=(4,7)]
+
+# A non-constant WITH expression cannot be inlined in the middle of
+# normalization.
+norm expect-not=InlineAnyWithScan
+WITH ivals AS (SELECT * FROM unnest(ARRAY(SELECT i FROM t87790)))
+SELECT * FROM t87790 WHERE i IN (SELECT * FROM ivals)
+----
+semi-join (hash)
+ ├── columns: i:7!null j:8!null k:9
+ ├── immutable
+ ├── key: (7,8)
+ ├── fd: (7,8)-->(9)
+ ├── scan t87790
+ │    ├── columns: i:7!null j:8!null k:9
+ │    ├── key: (7,8)
+ │    └── fd: (7,8)-->(9)
+ ├── project
+ │    ├── columns: unnest:12
+ │    ├── immutable
+ │    ├── project-set
+ │    │    ├── columns: unnest:6
+ │    │    ├── immutable
+ │    │    ├── values
+ │    │    │    ├── cardinality: [1 - 1]
+ │    │    │    ├── key: ()
+ │    │    │    └── ()
+ │    │    └── zip
+ │    │         └── function: unnest [immutable, subquery]
+ │    │              └── array-flatten
+ │    │                   └── scan t87790
+ │    │                        └── columns: i:1!null
+ │    └── projections
+ │         └── unnest:6 [as=unnest:12, outer=(6)]
+ └── filters
+      └── i:7 = unnest:12 [outer=(7,12), constraints=(/7: (/NULL - ]; /12: (/NULL - ]), fd=(7)==(12), (12)==(7)]
+
+# Placeholders are considered constant for the InlineAnyWithScan normalization.
+assign-placeholders-norm query-args=(1, 2, 3)
+WITH ivals AS (SELECT * FROM unnest(ARRAY[$1::INT, $2::INT, $3::INT]))
+SELECT * FROM t87790 WHERE i IN (SELECT * FROM ivals)
+----
+select
+ ├── columns: i:2!null j:3!null k:4
+ ├── key: (2,3)
+ ├── fd: (2,3)-->(4)
+ ├── scan t87790
+ │    ├── columns: i:2!null j:3!null k:4
+ │    ├── key: (2,3)
+ │    └── fd: (2,3)-->(4)
+ └── filters
+      └── i:2 IN (1, 2, 3) [outer=(2), constraints=(/2: [/1 - /1] [/2 - /2] [/3 - /3]; tight)]
+
+norm expect=InlineAnyWithScan
+WITH v(a,b) AS (VALUES (1,2))
+SELECT 1 FROM t87790 WHERE i IN (SELECT a FROM v)
+UNION ALL
+SELECT 1 FROM t87790 WHERE j IN (SELECT b FROM v)
+----
+union-all
+ ├── columns: "?column?":19!null
+ ├── left columns: "?column?":10
+ ├── right columns: "?column?":18
+ ├── project
+ │    ├── columns: "?column?":10!null
+ │    ├── fd: ()-->(10)
+ │    ├── select
+ │    │    ├── columns: i:3!null
+ │    │    ├── fd: ()-->(3)
+ │    │    ├── scan t87790
+ │    │    │    └── columns: i:3!null
+ │    │    └── filters
+ │    │         └── i:3 = 1 [outer=(3), constraints=(/3: [/1 - /1]; tight), fd=()-->(3)]
+ │    └── projections
+ │         └── 1 [as="?column?":10]
+ └── project
+      ├── columns: "?column?":18!null
+      ├── fd: ()-->(18)
+      ├── select
+      │    ├── columns: j:12!null
+      │    ├── fd: ()-->(12)
+      │    ├── scan t87790
+      │    │    └── columns: j:12!null
+      │    └── filters
+      │         └── j:12 = 2 [outer=(12), constraints=(/12: [/2 - /2]; tight), fd=()-->(12)]
+      └── projections
+           └── 1 [as="?column?":18]

pkg/sql/opt/norm/with_funcs.go

@@ -13,6 +13,7 @@ package norm
 import (
 	"github.com/cockroachdb/cockroach/pkg/sql/opt"
 	"github.com/cockroachdb/cockroach/pkg/sql/opt/memo"
+	"github.com/cockroachdb/errors"
 )
 
 // CanInlineWith returns whether or not it's valid to inline binding in expr.
@@ -61,3 +62,68 @@ func (c *CustomFuncs) InlineWith(binding, input memo.RelExpr, priv *memo.WithPri
 
 	return replace(input).(memo.RelExpr)
 }
+
+// CanInlineWithScan returns whether or not it's valid and heuristically cheaper
+// to inline a WithScanExpr with its bound expression from the memo. Currently
+// this only allows inlining leak-proof constant VALUES clauses of the form
+// `column IN (VALUES(...))` or `column NOT IN(VALUES(...))`, but could likely
+// be extended to handle other expressions in the future.
+func (c *CustomFuncs) CanInlineWithScan(private *memo.WithScanPrivate, scalar opt.ScalarExpr) bool {
+	if !private.CanInlineInPlace {
+		return false
+	}
+	// If we don't have `column IN(...)` or `column NOT IN(...)` or
+	// (col1, col2 ... coln) IN/NOT IN (...), it is not cheaper to inline because
+	// we wouldn't be avoiding one or more joins.
+	if tupleExpr, ok := scalar.(*memo.TupleExpr); ok {
+		for _, scalarExpr := range tupleExpr.Elems {
+			if scalarExpr.Op() != opt.VariableOp {
+				return false
+			}
+		}
+	} else if scalar.Op() != opt.VariableOp {
+		return false
+	}
+	expr := c.mem.Metadata().WithBinding(private.With)
+	var valuesExpr *memo.ValuesExpr
+	var ok bool
+	if valuesExpr, ok = expr.(*memo.ValuesExpr); !ok {
+		return false
+	}
+	if !valuesExpr.IsConstantsAndPlaceholders() {
+		return false
+	}
+	return true
+}
+
+// InlineWithScan replaces a WithScanExpr with its bound expression, mapped to
+// new output ColumnIDs.
+func (c *CustomFuncs) InlineWithScan(private *memo.WithScanPrivate) memo.RelExpr {
+	expr := c.mem.Metadata().WithBinding(private.With)
+	var valuesExpr *memo.ValuesExpr
+	var ok bool
+	valuesExpr.Op()
+	if valuesExpr, ok = expr.(*memo.ValuesExpr); !ok {
+		// Didn't find the expected VALUES.
+		panic(errors.AssertionFailedf("attempt to inline a WithScan which is not a VALUES clause; operator: %s",
+			expr.Op().String()))
+	}
+	projections := make(memo.ProjectionsExpr, len(private.InCols))
+	for i := range private.InCols {
+		projections[i] = c.f.ConstructProjectionsItem(
+			c.f.ConstructVariable(private.InCols[i]),
+			private.OutCols[i],
+		)
+	}
+	// Shallow copy the values in case this WITH binding is inlined more than
+	// once.
+	newRows := make(memo.ScalarListExpr, len(valuesExpr.Rows))
+	copy(newRows, valuesExpr.Rows)
+	newCols := make(opt.ColList, len(valuesExpr.ValuesPrivate.Cols))
+	copy(newCols, valuesExpr.ValuesPrivate.Cols)
+	newValuesExpr := c.f.ConstructValues(newRows, &memo.ValuesPrivate{
+		Cols: newCols,
+		ID:   c.f.Metadata().NextUniqueID(),
+	})
+	return c.f.ConstructProject(newValuesExpr, projections, opt.ColSet{})
+}

pkg/sql/opt/ops/relational.opt

@@ -1313,6 +1313,11 @@ define WithScanPrivate {
     # most cases the column set is sufficient to do this, but various rules make
     # it possible to construct WithScan expressions with no columns.
     ID UniqueID
+
+    # CanInlineInPlace is true when the WithScanExpr is allowed to be inlined
+    # when it is normalized as opposed to inlining which takes place when the
+    # WithExpr is normalized.
+    CanInlineInPlace bool
 }
 
 # RecursiveCTE implements the logic of a recursive CTE:

pkg/sql/opt/optbuilder/select.go

@@ -99,11 +99,12 @@ func (b *Builder) buildDataSource(
 			}
 
 			outScope.expr = b.factory.ConstructWithScan(&memo.WithScanPrivate{
-				With:    cte.id,
-				Name:    string(cte.name.Alias),
-				InCols:  inCols,
-				OutCols: outCols,
-				ID:      b.factory.Metadata().NextUniqueID(),
+				With:             cte.id,
+				Name:             string(cte.name.Alias),
+				InCols:           inCols,
+				OutCols:          outCols,
+				ID:               b.factory.Metadata().NextUniqueID(),
+				CanInlineInPlace: !cte.mtr.Set || !cte.mtr.Materialize,
 			})
 
 			return outScope
@@ -205,11 +206,12 @@ func (b *Builder) buildDataSource(
 		}
 
 		outScope.expr = b.factory.ConstructWithScan(&memo.WithScanPrivate{
-			With:    cte.id,
-			Name:    string(cte.name.Alias),
-			InCols:  inCols,
-			OutCols: outCols,
-			ID:      b.factory.Metadata().NextUniqueID(),
+			With:             cte.id,
+			Name:             string(cte.name.Alias),
+			InCols:           inCols,
+			OutCols:          outCols,
+			ID:               b.factory.Metadata().NextUniqueID(),
+			CanInlineInPlace: !cte.mtr.Set || !cte.mtr.Materialize,
 		})
 
 		return outScope